Search results for: Wing Kam Fung

Authors: Chandra Shekhar Prasad, Ludek Pesek Prasad

Abstract:

In the present day fan blade of aero engine, turboprop propellers, gas turbine or steam turbine low-pressure blades are getting bigger, lighter and thus, become more flexible. Therefore, flutter, forced blade response and vibration related failure of the high aspect ratio blade are of main concern for the designers, thus need to be address properly in order to achieve successful component design. At the preliminary design stage large number of design iteration is need to achieve the utter free safe design. Most of the numerical method used for aeroelastic analysis is based on field-based methods such as finite difference method, finite element method, finite volume method or coupled. These numerical schemes are used to solve the coupled fluid Flow-Structural equation based on full Naiver-Stokes (NS) along with structural mechanics’ equations. These type of schemes provides very accurate results if modeled properly, however, they are computationally very expensive and need large computing recourse along with good personal expertise. Therefore, it is not the first choice for aeroelastic analysis during preliminary design phase. A reduced order aeroelastic model (ROAM) with acceptable accuracy and fast execution is more demanded at this stage. Similar ROAM are being used by other researchers for aeroelastic and force response analysis of turbomachinery. In the present paper new medium fidelity ROAM is successfully developed and implemented in numerical tool to simulated the aeroelastic stability phenomena in turbomachinery and well as flexible wings. In the present, a hybrid flow solver based on 3D viscous-inviscid coupled 3D panel method (PM) and 3d discrete vortex particle method (DVM) is developed, viscous parameters are estimated using boundary layer(BL) approach. This method can simulate flow separation and is a good compromise between accuracy and speed compared to CFD. In the second phase of the research work, the flow solver (PM) will be coupled with ROM non-linear beam element method (BEM) based FEM structural solver (with multibody capabilities) to perform the complete aeroelastic simulation of a steam turbine bladed disk, propellers, fan blades, aircraft wing etc. The partitioned based coupling approach is used for fluid-structure interaction (FSI). The numerical results are compared with experimental data for different test cases and for the blade cascade test case, experimental data is obtained from in-house lab experiments at IT CAS. Furthermore, the results from the new aeroelastic model will be compared with classical CFD-CSD based aeroelastic models. The proposed methodology for the aeroelastic stability analysis of gas turbine or steam turbine blades, or propellers or fan blades will provide researchers and engineers a fast, cost-effective and efficient tool for aeroelastic (classical flutter) analysis for different design at preliminary design stage where large numbers of design iteration are required in short time frame.

Keywords: aeroelasticity, beam element method (BEM), discrete vortex particle method (DVM), classical flutter, fluid-structure interaction (FSI), panel method, reduce order aeroelastic model (ROAM), turbomachinery, viscous-inviscid coupling

Procedia PDF Downloads 232

Authors: Melanie Schinnerl, Dorothea Greiling

Abstract:

In the context of the 2020 strategy, poverty and its fight returned to the center of national political efforts. This served as motivation for an Austrian research grant-funded project to focus on the under-researched local government level with the aim to identify municipal best-practice cases and to derive policy implications for Austria. Designing effective poverty reduction strategies is a complex challenge which calls for an integrated multi-actor in approach. Cities are increasingly confronted to combat poverty, even in rich EU-member states. By doing so cities face substantial demographic, cultural, economic and social challenges as well as changing welfare state regimes. Furthermore, there is a low willingness of (right-wing) governments to support the poor. Against this background, the research questions are: 1. How do local governments define poverty? 2. Who are the main risk groups and what are the most pressing problems when fighting urban poverty? 3. What is regarded as successful anti-poverty initiatives? 4. What is the underlying welfare state concept? To address the research questions a multi-method approach was chosen, consisting of a systematic literature analysis, a comprehensive document analysis, and expert interviews. For interpreting the data the project follows the qualitative-interpretive paradigm. Municipal approaches for reducing poverty are compared based on deductive, as well as inductive identified criteria. In addition to an intensive literature analysis, interviews (40) were conducted in Austria since the project started in March 2018. From the other countries, 14 responses have been collected, providing a first insight. Regarding the definition of poverty the EU SILC-definition as well as counting the persons who receive need-based minimum social benefits, the Austrian form of social welfare, are the predominant approaches in Austria. In addition to homeless people, single-parent families, un-skilled persons, long-term unemployed persons, migrants (first and second generation), refugees and families with at least 3 children were frequently mentioned. The most pressing challenges for Austrian cities are: expected reductions of social budgets, a great insecurity of the central government's social policy reform plans, the growing number of homeless people and a lack of affordable housing. Together with affordable housing, old-age poverty will gain more importance in the future. The Austrian best practice examples, suggested by interviewees, focused primarily on homeless, children and young people (till 25). Central government’s policy changes have already negative effects on programs for refugees and elderly unemployed. Social Housing in Vienna was frequently mentioned as an international best practice case, other growing cities can learn from. The results from Austria indicate a change towards the social investment state, which primarily focuses on children and labour market integration. The first insights from the other countries indicate that affordable housing and labor market integration are cross-cutting issues. Inherited poverty and old-age poverty seems to be more pressing outside Austria.

Keywords: anti-poverty policies, European cities, empirical study, social investment

Procedia PDF Downloads 89

Authors: Salvatore Luongo, Carlo Luongo

Abstract:

This paper discusses the implementation solutions to reduce the computational load for the Traffic Situational Awareness with Alerts (TSAA) application, based on Automatic Dependent Surveillance-Broadcast (ADS-B) technology. In 2008, there were 23 total mid-air collisions involving general aviation fixed-wing aircraft, 6 of which were fatal leading to 21 fatalities. These collisions occurred during visual meteorological conditions, indicating the limitations of the see-and-avoid concept for mid-air collision avoidance as defined in the Federal Aviation Administration’s (FAA). The commercial aviation aircraft are already equipped with collision avoidance system called TCAS, which is based on classic transponder technology. This system dramatically reduced the number of mid-air collisions involving air transport aircraft. In general aviation, the same reduction in mid-air collisions has not occurred, so this reduction is the main objective of the TSAA application. The major difference between the original conflict detection application and the TSAA application is that the conflict detection is focused on preventing loss of separation in en-route environments. Instead TSAA is devoted to reducing the probability of mid-air collision in all phases of flight. The TSAA application increases the flight crew traffic situation awareness providing alerts of traffic that are detected in conflict with ownship in support of the see-and-avoid responsibility. The relevant effort has been spent in the design process and the code generation in order to maximize the efficiency and performances in terms of computational load and memory consumption reduction. The TSAA architecture is divided into two high-level systems: the “Threats database” and the “Conflict detector”. The first one receives the traffic data from ADS-B device and provides the memorization of the target’s data history. Conflict detector module estimates ownship and targets trajectories in order to perform the detection of possible future loss of separation between ownship and each target. Finally, the alerts are verified by additional conflict verification logic, in order to prevent possible undesirable behaviors of the alert flag. In order to reduce the computational load, a pre-check evaluation module is used. This pre-check is only a computational optimization, so the performances of the conflict detector system are not modified in terms of number of alerts detected. The pre-check module uses analytical trajectories propagation for both target and ownship. This allows major accuracy and avoids the step-by-step propagation, which requests major computational load. Furthermore, the pre-check permits to exclude the target that is certainly not a threat, using an analytical and efficient geometrical approach, in order to decrease the computational load for the following modules. This software improvement is not suggested by FAA documents, and so it is the main innovation of this work. The efficiency and efficacy of this enhancement are verified using fast-time and real-time simulations and by the execution on a real device in several FAA scenarios. The final implementation also permits the FAA software certification in compliance with DO-178B standard. The computational load reduction allows the installation of TSAA application also on devices with multiple applications and/or low capacity in terms of available memory and computational capabilities

Keywords: traffic situation awareness, general aviation, aircraft conflict detection, computational load reduction, implementation solutions, software certification

Procedia PDF Downloads 251