Search results for: turbine blade cooling

Authors: Jiri Cecrdle

Abstract:

This paper describes the concept of the W-WING whirl flutter aeroelastic demonstrator. Whirl flutter is the specific case of flutter that accounts for the additional dynamic and aerodynamic influences of the engine rotating parts. The instability is driven by motion-induced unsteady aerodynamic propeller forces and moments acting in the propeller plane. Whirl flutter instability is a serious problem that may cause the unstable vibration of a propeller mounting, leading to the failure of an engine installation or an entire wing. The complicated physical principle of whirl flutter required the experimental validation of the analytically gained results. W-WING aeroelastic demonstrator has been designed and developed at Czech Aerospace Research Centre (VZLU) Prague, Czechia. The demonstrator represents the wing and engine of the twin turboprop commuter aircraft. Contrary to the most of past demonstrators, it includes a powered motor and thrusting propeller. It allows the changes of the main structural parameters influencing the whirl flutter stability characteristics. Propeller blades are adjustable at standstill. The demonstrator is instrumented by strain gauges, accelerometers, revolution-counting impulse sensor, sensor of airflow velocity, and the thrust measurement unit. Measurement is supported by the in house program providing the data storage and real-time depiction in the time domain as well as pre-processing into the form of the power spectral densities. The engine is linked with a servo-drive unit, which enables maintaining of the propeller revolutions (constant or controlled rate ramp) and monitoring of immediate revolutions and power. Furthermore, the program manages the aerodynamic excitation of the demonstrator by the aileron flapping (constant, sweep, impulse). Finally, it provides the safety guard to prevent any structural failure of the demonstrator hardware. In addition, LMS TestLab system is used for the measurement of the structure response and for the data assessment by means of the FFT- and OMA-based methods. The demonstrator is intended for the experimental investigations in the VZLU 3m-diameter low-speed wind tunnel. The measurement variant of the model is defined by the structural parameters: pitch and yaw attachment stiffness, pitch and yaw hinge stations, balance weight station, propeller type (duralumin or steel blades), and finally, angle of attack of the propeller blade 75% section (). The excitation is provided either by the airflow turbulence or by means of the aerodynamic excitation by the aileron flapping using a frequency harmonic sweep. The experimental results are planned to be utilized for validation of analytical methods and software tools in the frame of development of the new complex multi-blade twin-rotor propulsion system for the new generation regional aircraft. Experimental campaigns will include measurements of aerodynamic derivatives and measurements of stability boundaries for various configurations of the demonstrator.

Keywords: aeroelasticity, flutter, whirl flutter, W WING demonstrator

Procedia PDF Downloads 94

Authors: M. Baratieri, M. Beccali, S. Corradino, B. Di Pietra, C. La Grassa, F. Monteleone, G. Morosinotto, G. Puglisi

Abstract:

The energy renovation of existing buildings represents an important opportunity to increase the decarbonization and the sustainability of urban environments. In this context, the work carried out has the objective of demonstrating the technical and economic feasibility of an energy renovate of a public building destined for offices located on the island of Lampedusa in the Mediterranean Sea. By applying the Italian transpositions of European Directives 2010/31/EU and 2009/28/EC, the building has been renovated from the current energy requirements of 111.7 kWh/m² to 16.4 kWh/m². The result achieved classifies the building as nZEB (nearly Zero Energy Building) according to the Italian national definition. The analysis was carried out using in parallel a quasi-stationary software, normally used in the professional field, and a dynamic simulation model often used in the academic world. The proposed interventions cover the components of the building’s envelope, the heating-cooling system and the supply of energy from renewable sources. In these latter points, the analysis has focused more on assessing two aspects that affect the supply of renewable energy. The first concerns the use of advanced logic control systems for air conditioning units in order to increase photovoltaic self-consumption. With these adjustments, a considerable increase in photovoltaic self-consumption and a decrease in the electricity exported to the Island's electricity grid have been obtained. The second point concerned the evaluation of the building's energy classification considering the real efficiency of the heating-cooling plant. Normally the energy plants have lower operational efficiency than the designed one due to multiple reasons; the decrease in the energy classification of the building for this factor has been quantified. This study represents an important example for the evaluation of the best interventions for the energy renovation of buildings in the Mediterranean Climate and a good description of the correct methodology to evaluate the resulting improvements.

Keywords: heat pumps, HVAC systems, nZEB renovation, renewable energy sources

Procedia PDF Downloads 451

Authors: Iyad Al-Attar

Abstract:

Air filters installed in HVAC equipment and gas turbine for power generation confront several atmospheric contaminants with various concentrations while operating in different environments (tropical, coastal, hot). This leads to engine performance degradation, as contaminants are capable of deteriorating components and fouling compressor assembly. Compressor fouling is responsible for 70 to 85% of gas turbine performance degradation leading to reduction in power output and availability and an increase in the heat rate and fuel consumption. Therefore, filter design must take into account face velocities, pleat count and its corresponding surface area; to verify filter performance characteristics (Efficiency and Pressure Drop). The experimental work undertaken in the current study examined two groups of four filters with different pleating densities were investigated for the initial pressure drop response and fractional efficiencies. The pleating densities used for this study is 28, 30, 32 and 34 pleats per 100mm for each pleated panel and measured for ten different flow rates ranging from 500 to 5000 m3/h with increment of 500m3/h. This experimental work of the current work has highlighted the underlying reasons behind the reduction in filter permeability due to the increase in face velocity and pleat density. The reasons that led to surface area losses of filtration media are due to one or combination of the following effects: pleat-crowding, deflection of the entire pleated panel, pleat distortion at the corner of the pleat and/or filtration medium compression. It is evident from entire array of experiments that as the particle size increases, the efficiency decreases until the MPPS is reached. Beyond the MPPS, the efficiency increases with increase in particle size. The MPPS shifts to a smaller particle size as the face velocity increases, while the pleating density and orientation did not have a pronounced effect on the MPPS. Throughout the study, an optimal pleat count which satisfies initial pressure drop and efficiency requirements may not have necessarily existed. The work has also suggested that a valid comparison of the pleat densities should be based on the effective surface area that participates in the filtration action and not the total surface area the pleat density provides.

Keywords: air filters, fractional efficiency, gas cleaning, glass fibre, HEPA filter, permeability, pressure drop

Procedia PDF Downloads 134

Authors: Y. Galerkin, E. Popova, K. Soldatova

Abstract:

There is an evident trend to elevate pressure ratio of a single stage of a turbo compressors - axial compressors in particular. Whilst there was an opinion recently that a pressure ratio 1,9 was a reasonable limit, later appeared information on successful modeling tested of stages with pressure ratio up to 2,8. The Authors recon that lack of information on high pressure stages makes actual a study of rational choice of design parameters before high supersonic flow problems solving. The computer program of an engineering type was developed. Below is presented a sample of its application to study possible parameters of the impeller of the stage with pressure ratio π*=3,0. Influence of two main design parameters on expected efficiency, periphery blade speed and flow structure is demonstrated. The results had lead to choose a variant for further analysis and improvement by CFD methods.

Keywords: supersonic stage, impeller, efficiency, flow rate coefficient, work coefficient, loss coefficient, oblique shock, direct shock

Procedia PDF Downloads 462

Authors: F. Rahimi Dehgolan, S. E. Khadem, S. Bab, M. Najafee

Abstract:

Nowadays, using rotating systems like shafts and disks in industrial machines have been increased constantly. Dynamic stability is one of the most important factors in designing rotating systems. In this study, linear frequencies and stability of a coupled continuous flexible rotor-disk-blades system are studied. The Euler-Bernoulli beam theory is utilized to model the blade and shaft. The equations of motion are extracted using the extended Hamilton principle. The equations of motion have been simplified using the Coleman and complex transformations method. The natural frequencies of the linear part of the system are extracted, and the effects of various system parameters on the natural frequencies and decay rates (stability condition) are clarified. It can be seen that the centrifugal stiffening effect applied to the blades is the most important parameter for stability of the considered rotating system. This result highlights the importance of considering this stiffing effect in blades equation.

Keywords: rotating shaft, flexible blades, centrifugal stiffness, stability

Procedia PDF Downloads 264

Authors: Francis C. Emejeamara, Alison S. Tomlin, James Gooding

Abstract:

Due to the highly turbulent nature of urban air flows, and by virtue of the fact that turbines are likely to be located within the roughness sublayer of the urban boundary layer, proposed urban wind installations are faced with major challenges compared to rural installations. The challenge of operating within turbulent winds can however, be counteracted by the development of suitable gust tracking solutions. In order to assess the cost effectiveness of such controls, a detailed understanding of the urban wind resource, including its turbulent characteristics, is required. Estimating the ambient turbulence and total kinetic energy available at different control response times is essential in evaluating the potential performance of wind systems within the urban environment should effective control solutions be employed. However, high resolution wind measurements within the urban roughness sub-layer are uncommon, and detailed CFD modelling approaches are too computationally expensive to apply routinely on a city wide scale. This paper therefore presents an alternative semi-empirical methodology for estimating the excess energy content (EEC) present in the complex and gusty urban wind. An analytical methodology for predicting the total wind energy available at a potential turbine site is proposed by assessing the relationship between turbulence intensities and EEC, for different control response times. The semi-empirical model is then incorporated with an analytical methodology that was initially developed to predict mean wind speeds at various heights within the built environment based on detailed mapping of its aerodynamic characteristics. Based on the current methodology, additional estimates of turbulence intensities and EEC allow a more complete assessment of the available wind resource. The methodology is applied to 4 UK cities with results showing the potential of mapping turbulence intensities and the total wind energy available at different heights within each city. Considering the effect of ambient turbulence and choice of wind system, the wind resource over neighbourhood regions (of 250 m uniform resolution) and building rooftops within the 4 cities were assessed with results highlighting the promise of mapping potential turbine sites within each city.

Keywords: excess energy content, small-scale wind, turbulence intensity, urban wind energy, wind resource assessment

Procedia PDF Downloads 472

Authors: Rishi Sharma, S. N. Maiti

Abstract:

The non-isothermal crystallization kinetics of PP/SEBS-g-MA blends up to 0-50% concentration of copolymer was studied by differential scanning calorimetry at four different cooling rates. Crystallization parameters were analyzed by Avrami and Jeziorny models. Primary and secondary crystallization processes were described by Avrami equation. Avrami model showed that all types of shapes grow from small dimensions during primary crystallization. However, three-dimensional crystal growth was observed during the secondary crystallization process. The crystallization peak and onset temperature decrease, however

Keywords: crystallization kinetics, non-isothermal, polypropylene, SEBS-g-MA

Procedia PDF Downloads 620

Authors: Samain Sabrin, Joshua Pratt, Joshua Bryk, Maryam Karimi

Abstract:

Globally, extreme heat events have led to a surge in the number of heat-related moralities. These incidents are further exacerbated in high-density population centers due to the Urban Heat Island (UHI) effect. Varieties of anthropogenic activities such as unsupervised land surface modifications, expansion of impervious areas, and lack of use of vegetation are all contributors to an increase in the amount of heat flux trapped by an urban canopy which intensifies the UHI effect. This project aims to propose a systematic approach to measure the impact of air quality and increased temperature based on urban morphology in the selected metropolitan cities. This project will measure the impact of build environment for urban and regional planning using human biometeorological evaluations (mean radiant temperature, Tmrt). We utilized the Rayman model (capable of calculating short and long wave radiation fluxes affecting the human body) to estimate the Tmrt in an urban environment incorporating location and height of buildings and trees as a supplemental tool in urban planning, and street design. Our current results suggest a strong correlation between building height and increased surface temperature in megacities. This model will help with; 1. Quantify the impacts of the built environment and surface properties on surrounding temperature, 2. Identify priority urban neighborhoods by analyzing Tmrt and air quality data at pedestrian level, 3. Characterizing the need for urban green infrastructure or better urban planning- maximizing the cooling benefit from existing Urban Green Infrastructure (UGI), and 4. Developing a hierarchy of streets for new UGI integration and propose new UGI based on site characteristics and cooling potential.

Keywords: air quality, heat mitigation, human-biometeorological indices, increased temperature, mean radiant temperature, radiation flux, sustainable development, thermal comfort, urban canopy, urban planning

Procedia PDF Downloads 140

Authors: Paula Marín, Mohammad Saffari, Alvaro de Gracia, Luisa F. Cabeza, Svetlana Ushak

Abstract:

Climate control represents an important issue when referring to energy consumption of buildings and associated expenses, both in installation or operation periods. The climate control of a building relies on several factors. Among them, localization, orientation, architectural elements, sources of energy used, are considered. In order to study the thermal behaviour of a building set up, the present study proposes the use of energy simulation program Energy Plus. In recent years, energy simulation programs have become important tools for evaluation of thermal/energy performance of buildings and facilities. Besides, the need to find new forms of passive conditioning in buildings for energy saving is a critical component. The use of phase change materials (PCMs) for heat storage applications has grown in importance due to its high efficiency. Therefore, the climatic conditions of Northern Chile: high solar radiation and extreme temperature fluctuations ranging from -10°C to 30°C (Calama city), low index of cloudy days during the year are appropriate to take advantage of solar energy and use passive systems in buildings. Also, the extensive mining activities in northern Chile encourage the use of large numbers of containers to harbour workers during shifts. These containers are constructed with lightweight construction systems, requiring heating during night and cooling during day, increasing the HVAC electricity consumption. The use of PCM can improve thermal comfort and reduce the energy consumption. The objective of this study was to evaluate the thermal and energy performance of containers of 2.5×2.5×2.5 m3, located in four cities of Chile: Antofagasta, Calama, Santiago, and Concepción. Lightweight envelopes, typically used in these building prototypes, were evaluated considering a container without PCM inclusion as the reference building and another container with PCM-enhanced envelopes as a test case, both of which have a door and a window in the same wall, orientated in two directions: North and South. To see the thermal response of these containers in different seasons, the simulations were performed considering a period of one year. The results show that higher energy savings for the four cities studied are obtained when the distribution of door and window in the container is in the north direction because of higher solar radiation incidence. The comparison of HVAC consumption and energy savings in % for north direction of door and window are summarised. Simulation results show that in the city of Antofagasta 47% of heating energy could be saved and in the cities of Calama and Concepción the biggest savings in terms of cooling could be achieved since PCM reduces almost all the cooling demand. Currently, based on simulation results, four containers have been constructed and sized with the same structural characteristics carried out in simulations, that are, containers with/without PCM, with door and window in one wall. Two of these containers will be placed in Antofagasta and two containers in a copper mine near to Calama, all of them will be monitored for a period of one year. The simulation results will be validated with experimental measurements and will be reported in the future.

Keywords: energy saving, lightweight construction, PCM, simulation

Procedia PDF Downloads 281

Authors: Tapas Kumar Sinha, Joseph Mathew

Abstract:

At the moment earth is in grave danger due to threats of global warming. The temperature of the earth has risen by almost 20C. Glaciers in the Arctic have started to melt. It would be foolhardy to think that this is a small effect and in time it would go away. Global warming is caused by a number of factors. However, one sure and simple way to totally eliminate this problem is to put programmable shields in space. Just as an umbrella blocks sunlight, a programmable shield in space will block sun rays from reaching the earth as in a solar eclipse and cause cooling in the penumbral region just as it happens during an eclipse.

Keywords: glaciers, green house, global warming space, satellites

Procedia PDF Downloads 596

Authors: Baha Vural Kök, Mehmet Yilmaz, Mustafa Akpolat, Cihat Sav

Abstract:

Various types of additives are used frequently in order to improve the rheological and mechanical properties of bituminous mixtures. Small devices instead of full scale machines are used for bitumen modification in the laboratory. These laboratory scale devices vary in terms of their properties such as mixing rate, mixing blade and the amount of binder. In this study, the effect of mixing rate and time during the bitumen modification processes on conventional and rheological properties of pure and crumb rubber modified binder were investigated. Penetration, softening point, rotational viscosity (RV) and dynamic shear rheometer (DSR) tests were applied to pure and CR modified bitumen. It was concluded that the penetration and softening point test did not show the efficiency of CR obtained by different mixing conditions. Besides, oxidation that occurred during the preparation processes plays a great part in the improvement effects of the modified binder.

Keywords: bitumen, crumb rubber, modification, rheological properties

Procedia PDF Downloads 313

Authors: N. Zerzouri, N. Benalia, N. Bensiali

Abstract:

This work is devoted to an analysis of the operation of a doubly fed induction generator (DFIG) integrated with a wind system. The power transfer between the stator and the network is carried out by acting on the rotor via a bidirectional signal converter. The analysis is devoted to the study of a fault in the converter due to an interruption of the control of a semiconductor. Simulation results obtained by the MATLAB / Simulink software illustrate the quality of the power generated at the default.

Keywords: doubly fed induction generator (DFIG), wind power generation, back to back PWM converter, default switching

Procedia PDF Downloads 463

Authors: Michal Bialy, Marcin Szlachetka, Mateusz Paszko

Abstract:

This paper discusses the CFD results of heat transfer in water channels in the engine body. The research engine was a newly designed Diesel combustion engine. The engine has three cylinders with three pairs of opposed pistons inside. The engine will be able to generate 100 kW mechanical power at a crankshaft speed of 3,800-4,000 rpm. The water channels are in the engine body along the axis of the three cylinders. These channels are around the three combustion chambers. The water channels transfer combustion heat that occurs the cylinders to the external radiator. This CFD research was based on the ANSYS Fluent software and aimed to optimize the geometry of the water channels. These channels should have a maximum flow of heat from the combustion chamber or the external radiator. Based on the parallel simulation research, the boundary and initial conditions enabled us to specify average values of key parameters for our numerical analysis. Our simulation used the average momentum equations and turbulence model k-epsilon double equation. There was also used a real k-epsilon model with a function of a standard wall. The turbulence intensity factor was 10%. The working fluid mass flow rate was calculated for a single typical value, specified in line with the research into the flow rate of automotive engine cooling pumps used in engines of similar power. The research uses a series of geometric models which differ, for instance, in the shape of the cross-section of the channel along the axis of the cylinder. The results are presented as colourful distribution maps of temperature, speed fields and heat flow through the cylinder walls. Due to limitations of space, our paper presents the results on the most representative geometric model only. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK ‘PZL-KALISZ’ S.A. and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.

Keywords: Ansys fluent, combustion engine, computational fluid dynamics CFD, cooling system

Procedia PDF Downloads 217

Authors: Amirhossein Eisapour, Mohammad Emamjome Kashan, Alan S. Fung

Abstract:

This research addresses the pressing global challenges of clean energy and water supplies, emphasizing the need for sustainable solutions for the building sector. The research centers on integrating Reverse Osmosis (RO) systems with building energy systems, incorporating Solar Thermal Collectors (STC)/Photovoltaic Thermal (PVT), water-to-water heat pumps, and an Insulated Concrete Form (ICF) based building foundation wall thermal energy storage. The study explores an innovative configuration’s effectiveness in addressing water and heating demands through clean energy sources while addressing ICF-based thermal storage challenges, which could overheat in the cooling season. Analyzing four configurations—STC-ICF, STC-ICF-RO, PVT-ICF, and PVT-ICF-RO, the study conducts a sensitivity analysis on collector area (25% and 50% increase) and weather data (evaluating five Canadian cities, Winnipeg, Toronto, Edmonton, Halifax and Vancouver). Key outcomes highlight the benefits of integrated RO scenarios, showcasing reduced ICF wall temperature, diminished unwanted heat in the cooling season, reduced RO pump consumption and enhanced solar energy production. The STC-ICF-RO and PVT-ICF-RO systems achieved energy savings of 653 kWh and 131 kWh, respectively, in comparison to their non-integrated RO counterparts. Additionally, both systems successfully contributed to lowering the CO2 production level of the energy system. The calculated payback period of STC-ICF-RO (2 years) affirms the proposed systems’ economic viability. Compared to the base system, which does not benefit from the ICF and RO integration with the building energy system, the STC-ICF-RO and PVT-ICF-RO demonstrate a dramatic energy consumption reduction of 20% and 32%, respectively. The sensitivity analysis suggests potential system improvements under specific conditions, especially when implementing the introduced energy system in communities of buildings.

Keywords: insulated concrete form, thermal energy storage, reverse osmosis, building energy systems, solar thermal collector, photovoltaic thermal, heat pump

Procedia PDF Downloads 52

Authors: Poonam Yadav, Dong Bok Lee

Abstract:

Isothermal oxidation at 800°C for 50h and Cyclic oxidation at 600°C and 800°C for 40h of Pure Ti and Ti64 were performed in a muffle furnace. In Cyclic oxidation, massive scale spallation occurred, and the oxide scale cracks and peels off were observed at high temperature, it represents oxide scale that formed during cyclic oxidation was spalled out owing to stresses due to thermal shock generated during repetitive oxidation and subsequent cooling. The thickness of scale is larger in cyclic oxidation than the isothermal case. This is due to inward diffusion of oxygen through oxide scales and/or pores and cracks in cyclic oxidation.

Keywords: cyclic, diffusion, isothermal, cyclic

Procedia PDF Downloads 917

Authors: C. Agrawal, R. Kumar, A. Gupta, B. Chatterjee

Abstract:

An experimental investigation has been carried out to study the cooling of a hot horizontal Stainless Steel surface of 3 mm thickness, which has 800±10 °C initial temperature. A round water jet of 22 ± 1 °C temperature was injected over the hot surface through straight tube type nozzles of 2.5-4.8 mm diameter and 250 mm length. The experiments were performed for the jet exit to target surface spacing of 4 times of jet diameter and jet Reynolds number of 5000-24000. The effect of change in jet Reynolds number on the surface quenching has been investigated form the stagnation point to 16 mm spatial location.

Keywords: hot-surface, jet impingement, quenching, stagnation point

Procedia PDF Downloads 608

Authors: Upamanyu Majumder, Angshuman Das

Abstract:

The Klimov RD-33 is a turbofan jet engine for a lightweight fighter jet that is the primary engine for the Mikoyan MiG-29. Its production started in 1981. The RD-33 was the first afterburning turbofan engine produced by the Klimov Company of Russia in the 8,000 to 9,000 kilograms-force (78,000 to 88,000 N; 18,000 to 20,000 lbf) thrust class. It features a modular twin-shaft design with individual parts that can be replaced separately and has a good tolerance to the environment. The RD-33 is simple to maintain and retains good performance in challenging environments. In this paper the stagnation properties(pressure and temperature) at the intake diffuser, compressor and turbine sections of the RD-33 engine are calculated using the standard atmosphere conditions at different altitudes( take-off, 5000m, 10000m, 15000m, 20000m and 22500m). The results are plotted against altitude values using MS-Excel.

Keywords: Klimov RD-33 engine, stagnation properties, various altitudes, ms-excel

Procedia PDF Downloads 357

Authors: Zamira Sattinova, Tassybek Bekenov

Abstract:

The article is devoted to modeling the technology of hot casting of beryllium oxide ceramics. The stages of ultrasonic activation of beryllium oxide slurry in the plant vessel to improve the rheological property, hot casting in the moulding cavity with cooling and solidification of the casting are described. Thermoplastic slurry (hereinafter referred to as slurry) shows the rheology of a non-Newtonian fluid with yield and plastic viscosity. Cooling-solidification of the slurry in the forming cavity occurs in the liquid, taking into account crystallization and solid state. In this work is the method of calculation of hot casting of the slurry using the method of effective molecular viscosity of viscoplastic fluid. It is shown that the slurry near the cooled wall is in a state of crystallization and plasticity, and the rest may still be in the liquid phase. Nonuniform distribution of temperature, density and concentration of kinetically free binder takes place along the cavity section. This leads to compensation of shrinkage by the influx of slurry from the liquid into the crystallization zones and plasticity of the castings. In the plasticity zone, the shrinkage determined by the concentration of kinetically free binder is compensated under the action of the pressure gradient. The solidification mechanism, as well as the mechanical behavior of the casting mass during casting, the rheological and thermophysical properties of the thermoplastic BeO slurry due to ultrasound exposure have not been well studied. Nevertheless, experimental data allow us to conclude that the effect of ultrasonic vibrations on the slurry mass leads to it: a change in structure, an increase in technological properties, a decrease in heterogeneity and a change in rheological properties. In the course of experiments, the effect of ultrasonic treatment and its duration on the change in viscosity and ultimate shear stress of the slurry depending on temperature (55-75℃) and the mass fraction of the binder (10 - 11.7%) have been studied. At the same time, changes in these properties before and after ultrasound exposure have been analyzed, as well as the nature of the flow in the system under study. The experience of operating the unit with ultrasonic impact has shown that at the same time, the casting capacity of the slurry increases by an average of 15%, and the viscosity decreases by more than half. Experimental study of physicochemical properties and phase change with simultaneous consideration of all factors affecting the quality of products in the process of continuous casting is labor-intensive. Therefore, an effective way to control the physical processes occurring in the formation of articles with predetermined properties and shapes is to simulate the process and determine its basic characteristics. The results of the calculations show the whole stage of hot casting of beryllium oxide slurry, taking into account the change in its state of aggregation. Ultrasonic treatment improves rheological properties and increases the fluidity of the slurry in the forming cavity. Calculations show the influence of velocity, temperature factors and structural data of the cavity on the cooling-solidification process of the casting. In the calculations, conditions for molding with shrinkage of the slurry by hot casting have been found, which makes it possible to obtain a solidifying product with a uniform beryllium oxide structure at the outlet of the cavity.

Keywords: hot casting, thermoplastic slurry molding, shrinkage, beryllium oxide

Procedia PDF Downloads 22

Authors: Hamid Reza Tabatabaiefar, Bita Mansoury, Mohammad Javad Khadivi Zand

Abstract:

The current energy and climate change impacts of the residential building sector in Australia are significant. Thus, the Australian Government has introduced more stringent regulations to improve building energy efficiency. In 2006, the Australian residential building sector consumed about 11% (around 440 Petajoule) of the total primary energy, resulting in total greenhouse gas emissions of 9.65 million tonnes CO2-eq. The gas and electricity consumption of residential dwellings contributed to 30% and 52% respectively, of the total primary energy utilised by this sector. Around 40 percent of total energy consumption of Australian buildings goes to heating and cooling due to the low thermal performance of the buildings. Thermal performance of buildings determines the amount of energy used for heating and cooling of the buildings which profoundly influences energy efficiency. Employing sustainable design principles and effective use of construction materials can play a crucial role in improving thermal performance of new and existing buildings. Even though awareness has been raised, the design phase of refurbishment projects is often problematic. One of the issues concerning the refurbishment of residential buildings is mostly the consumer market, where most work consists of moderate refurbishment jobs, often without assistance of an architect and partly without a building permit. There is an individual and often fragmental approach that results in lack of efficiency. Most importantly, the decisions taken in the early stages of the design determine the final result; however, the assessment of the environmental performance only happens at the end of the design process, as a reflection of the design outcome. Finally, studies have identified the lack of knowledge, experience and best-practice examples as barriers in refurbishment projects. In the context of sustainable development and the need to reduce energy demand, refurbishing the ageing residential building constitutes a necessary action. Not only it does provide huge potential for energy savings, but it is also economically and socially relevant. Although the advantages have been identified, the guidelines come in the form of general suggestions that fail to address the diversity of each project. As a result, it has been recognised that there is a strong need to develop guidelines for optimised retrofitting of existing residential buildings in order to improve their energy performance. The current study investigates the effectiveness of different energy retrofitting techniques and examines the impact of employing those methods on energy consumption of residential brick veneer buildings in Victoria (Australia). Proposing different remedial solutions for improving the energy performance of residential brick veneer buildings, in the simulation stage, annual energy usage analyses have been carried out to determine heating and cooling energy consumptions of the buildings for different proposed retrofitting techniques. Then, the results of employing different retrofitting methods have been examined and compared in order to identify the most efficient and cost-effective remedial solution for improving the energy performance of those buildings with respect to the climate condition in Victoria and construction materials of the studied benchmark building.

Keywords: brick veneer residential buildings, building energy efficiency, climate change impacts, cost effective remedial solution, energy performance, sustainable design principles

Procedia PDF Downloads 291

Authors: Yuexi Xiong, Jingwu He

Abstract:

The structural components in an energy facility such as steam turbine machines are operated under high stress and elevated temperature in an endured time period and thus the creep deformation and creep rupture failure are important issues that need to be addressed in the design of such components. There are numerous creep models being used for creep analysis that have both advantages and disadvantages in terms of accuracy and efficiency. The Isochronous Creep Analysis is one of the simplified approaches in which a full-time dependent creep analysis is avoided and instead an elastic-plastic analysis is conducted at each time point. This approach has been established based on the rupture dependent creep equations using the well-known Larson-Miller parameter. In this paper, some fundamental aspects of creep deformation and the rupture dependent creep models are reviewed and the analysis procedures using isochronous creep curves are discussed. Four rupture failure criteria are examined from creep fundamental perspectives including criteria of Stress Damage, Strain Damage, Strain Rate Damage, and Strain Capability. The accuracy of these criteria in predicting creep life is discussed and applications of the creep analysis procedures and failure predictions of simple models will be presented. In addition, a new failure criterion is proposed to improve the accuracy and effectiveness of the existing criteria. Comparisons are made between the existing criteria and the new one using several examples materials. Both strain increase and stress relaxation form a full picture of the creep behaviour of a material under high temperature in an endured time period. It is important to bear this in mind when dealing with creep problems. Accordingly there are two sets of rupture dependent creep equations. While the rupture strength vs LMP equation shows how the rupture time depends on the stress level under load controlled condition, the strain rate vs rupture time equation reflects how the rupture time behaves under strain-controlled condition. Among the four existing failure criteria for rupture life predictions, the Stress Damage and Strain Damage Criteria provide the most conservative and non-conservative predictions, respectively. The Strain Rate and Strain Capability Criteria provide predictions in between that are believed to be more accurate because the strain rate and strain capability are more determined quantities than stress to reflect the creep rupture behaviour. A modified Strain Capability Criterion is proposed making use of the two sets of creep equations and therefore is considered to be more accurate than the original Strain Capability Criterion.

Keywords: creep analysis, high temperature mateials, rapture evalution, steam turbine machines

Procedia PDF Downloads 287

Authors: Jiri Primas, Michal Malik, Darina Jasikova, Michal Kotek, Vaclav Kopecky

Abstract:

Authors of this paper discuss the measuring of volume ratio of two immiscible liquids in the homogenous mixture using the industrial Electrical Impedance Tomography (EIT) system ITS p2+. In the first part of the paper, the principle of EIT and the basic theory of conductivity of mixture of two components are stated. In the next part, the experiment with water and olive oil mixed with Rushton turbine is described, and the measured results are used to verify the theory. In the conclusion, the results are discussed in detail, and the accuracy of the measuring method and its advantages are also mentioned.

Keywords: conductivity, electrical impedance tomography, homogenous mixture, mixing process

Procedia PDF Downloads 400

Authors: Pradeep Joshi, Prashant Dhiman, Shiv Dayal Dhakad

Abstract:

Inconel 718 is a family if Nickel-Chromium based Superalloy; it has very high oxidation and corrosion resistance. Inconel 718 is widely being used in aerospace, engine, turbine etc. due to its high mechanical strength and creep resistance. Being widely used, its machining should be easy but in real its machining is very difficult, especially by using traditional machining methods. It becomes easy to machine only by using non Traditional machining such as EDM. During EDM machining there is wear of both tool and workpiece, the tool wear is undesired because it changes tool shape, geometry. To reduce the tool wear rate (TWR) cryogenic treatment is performed on tool before the machining operation. The machining performances of the process are to be evaluated in terms of MRR, TWR which are functions of Discharge current, Pulse on-time, Pulse Off-time.

Keywords: EDM, cyrogenic, TWR, MRR

Procedia PDF Downloads 453

Authors: Flur R. Ismagilov, Vyacheslav E. Vavilov, Denis V. Gusakov

Abstract:

This paper is devoted to solve the problem of increasing the electrification of aircraft engines by installing a synchronous generator at high pressure shaft. Technical solution of this problem by various research centers is discussed. A design solution of the problem was proposed. To evaluate the effectiveness of the proposed cooling system, thermal analysis was carried out in ANSYS software.

Keywords: starter-generator, more electrical engine, aircraft engines, high pressure shaft, synchronous generator

Procedia PDF Downloads 255

Authors: Dodi Ikhsanshaleh

Abstract:

When subjected to dynamic load, foundation oscillates in the way that depends on the soil behaviour, the geometry and inertia of the foundation and the dynamic exctation. The practical guideline to analysis block-type foundation excitated by dynamic load from vibrating machine is presented. The analysis use Lumped Mass Parameter Method to express dynamic properties such as stiffness and damping of soil. The numerical examples are performed on design block-type foundation supporting gas turbine compressor which is important equipment package in gas processing plant

Keywords: block foundation, dynamic load, lumped mass parameter

Procedia PDF Downloads 489

Authors: Sérgio S. de Jesus, Aline Santana, Rubens Maciel Filho

Abstract:

Global oxygen transfer coefficient (kLa) was characterized in a mechanically agitated airlift bio reactor. The experiments were carried out in an airlift bio reactor (3.2 L) with internal re circulation (a concentric draft-tube airlift vessel device); the agitation is carried out through a turbine Rushton impeller located along with the gas sparger in the region comprised in the riser. The experiments were conducted using xanthan gum (0.6%) at 250 C and a constant rotation velocity of 0 and 800 rpm, as well as in the absence of agitation (airlift mode); the superficial gas velocity varied from 0.0157 to 0.0262 ms-1. The volumetric oxygen transfer coefficient dependence of the rotational speed revealed that the presence of agitation increased up to two times the kLa value.

Keywords: aeration, mass transfer, non-Newtonian fluids, stirred airlift bioreactor

Procedia PDF Downloads 458

Authors: N. M. Thao, I. Dolguntseva, M. Leijon

Abstract:

Flow blockages referring to the increase in flow are considered as a vital equipment for marine current energy conversion. However, the shape of these devices will result in extracted energy under the operation. The present work investigates the effect of two configurations of a grating, convergent and divergent that located upstream, to the water flow velocity. Computational Fluid Dynamic simulation studies the flow characteristics by using the ANSYS Fluent solver for these specified arrangements of the grating. The results indicate that distinct features of flow velocity between “convergent” and “divergent” grating placements are up to in confined conditions. Furthermore, the velocity in case of granting is higher than that of the divergent grating.

Keywords: marine current energy, converter, turbine granting, RANS simulation, water flow velocity

Procedia PDF Downloads 408

Authors: R. Chakib, A. Essadki, M. Cherkaoui

Abstract:

This paper proposes the study of a robust control of the doubly fed induction generator (DFIG) used in a wind energy production. The proposed control is based on the linear active disturbance rejection control (ADRC) and it is applied to the control currents rotor of the DFIG, the DC bus voltage and active and reactive power exchanged between the DFIG and the network. The system under study and the proposed control are simulated using MATLAB/SIMULINK.

Keywords: doubly fed induction generator (DFIG), active disturbance rejection control (ADRC), vector control, MPPT, extended state observer, back-to-back converter, wind turbine

Procedia PDF Downloads 482

Authors: Eleni Tsangouri, Xander Hillewaere, David Garoz Gómez, Dimitrios Aggelis, Filip Du Prez, Danny Van Hemelrijck

Abstract:

Tapered Double Cantilever Beam (TDCB) is the most commonly used test set-up to evaluate the self-healing feature of thermoset polymers autonomously activated in the presence of crack. TDCB is a modification of the established fracture mechanics set-up of Double Cantilever Beam and is designed to provide constant strain energy release rate with crack length under stable load evolution (mode-I). In this study, the damage of virgin and autonomously healed TDCB polymer samples is evaluated considering the load-crack opening diagram, the strain maps provided by Digital Image Correlation technique and the fractography maps given by optical microscopy. It is shown that the pre-crack introduced prior to testing (razor blade tapping), the loading rate and the length of the side groove are the features that dominate the crack propagation and lead to inconstant fracture energy release rate.

Keywords: polymers, autonomous healing, fracture, tapered double cantilever beam

Procedia PDF Downloads 350

Authors: Boukelkoul Lahcen

Abstract:

The cumulative costs for O&M may represent as much as 65%-90% of the turbine's investment cost. Nowadays the cost effectiveness concept becomes a decision-making and technology evaluation metric. The cost of energy metric accounts for the effect replacement cost and unscheduled maintenance cost parameters. One key of the proposed approach is the idea of maintaining the WTs which can be captured via use of a finite state Markov chain. Such a model can be embedded within a probabilistic operation and maintenance simulation reflecting the action to be done. In this paper, an approach of estimating the cost of O&M is presented. The finite state Markov model is used for decision problems with number of determined periods (life cycle) to predict the cost according to various options of maintenance.

Keywords: cost, finite state, Markov model, operation and maintenance

Procedia PDF Downloads 531

Authors: V. Batishchev, V. Getman

Abstract:

We study the self-similar fluid flows in the Marangoni layers with the axial symmetry. Such flows are induced by the radial gradients of the temperatures whose distributions along the free boundary obey some power law. The self-similar solutions describe thermo-capillar flows both in the thin layers and in the case of infinite thickness. We consider both positive and negative temperature gradients. In the former case the cooling of free boundary nearby the axis of symmetry gives rise to the rotation of fluid. The rotating flow concentrates itself inside the Marangoni layer while outside of it the fluid does not revolve. In the latter case we observe no rotating flows at all. In the layers of infinite thickness the separation of the rotating flow creates two zones where the flows are directed oppositely. Both the longitudinal velocity and the temperature have exactly one critical point inside the boundary layer. It is worth to note that the profiles are monotonic in the case of non-swirling flows. We describe the flow outside the boundary layer with the use of self-similar solution of the Euler equations. This flow is slow and non-swirling. The introducing of an outer flow gives rise to the branching of swirling flows from the non-swirling ones. There is such the critical velocity of the outer flow that a non-swirling flow exists for supercritical velocities and cannot be extended to the sub-critical velocities. For the positive temperature gradients there are two non-swirling flows. For the negative temperature gradients the non-swirling flow is unique. We determine the critical velocity of the outer flow for which the branching of the swirling flows happens. In the case of a thin layer confined within free boundaries we show that the cooling of the free boundaries near the axis of symmetry leads to the separating of the layer and creates two sub-layers with opposite rotations inside. This makes sharp contrast with the case of infinite thickness. We show that such rotation arises provided the thickness of the layer exceed some critical value. In the case of a thin layer confined within free and rigid boundaries we construct the branching equation and the asymptotic approximation for the secondary swirling flows near the bifurcation point. It turns out that the bifurcation gives rise to one pair of the secondary swirling flows with different directions of swirl.

Keywords: free surface, rotation, fluid flow, bifurcation, boundary layer, Marangoni layer

Procedia PDF Downloads 343