Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4

Turbomachinery Related Abstracts

4 Workflow Based Inspection of Geometrical Adaptability from 3D CAD Models Considering Production Requirements

Authors: Tobias Huwer, Thomas Bobek, Gunter Spöcker


Driving forces for enhancements in production are trends like digitalization and individualized production. Currently, such developments are restricted to assembly parts. Thus, complex freeform surfaces are not addressed in this context. The need for efficient use of resources and near-net-shape production will require individualized production of complex shaped workpieces. Due to variations between nominal model and actual geometry, this can lead to changes in operations in Computer-aided process planning (CAPP) to make CAPP manageable for an adaptive serial production. In this context, 3D CAD data can be a key to realizing that objective. Along with developments in the geometrical adaptation, a preceding inspection method based on CAD data is required to support the process planner by finding objective criteria to make decisions about the adaptive manufacturability of workpieces. Nowadays, this kind of decisions is depending on the experience-based knowledge of humans (e.g. process planners) and results in subjective decisions – leading to a variability of workpiece quality and potential failure in production. In this paper, we present an automatic part inspection method, based on design and measurement data, which evaluates actual geometries of single workpiece preforms. The aim is to automatically determine the suitability of the current shape for further machining, and to provide a basis for an objective decision about subsequent adaptive manufacturability. The proposed method is realized by a workflow-based approach, keeping in mind the requirements of industrial applications. Workflows are a well-known design method of standardized processes. Especially in applications like aerospace industry standardization and certification of processes are an important aspect. Function blocks, providing a standardized, event-driven abstraction to algorithms and data exchange, will be used for modeling and execution of inspection workflows. Each analysis step of the inspection, such as positioning of measurement data or checking of geometrical criteria, will be carried out by function blocks. One advantage of this approach is its flexibility to design workflows and to adapt algorithms specific to the application domain. In general, within the specified tolerance range it will be checked if a geometrical adaption is possible. The development of particular function blocks is predicated on workpiece specific information e.g. design data. Furthermore, for different product lifecycle phases, appropriate logics and decision criteria have to be considered. For example, tolerances for geometric deviations are different in type and size for new-part production compared to repair processes. In addition to function blocks, appropriate referencing systems are important. They need to support exact determination of position and orientation of the actual geometries to provide a basis for precise analysis. The presented approach provides an inspection methodology for adaptive and part-individual process chains. The analysis of each workpiece results in an inspection protocol and an objective decision about further manufacturability. A representative application domain is the product lifecycle of turbine blades containing a new-part production and a maintenance process. In both cases, a geometrical adaptation is required to calculate individual production data. In contrast to existing approaches, the proposed initial inspection method provides information to decide between different potential adaptive machining processes.

Keywords: Turbomachinery, Adaptive, CAx, function blocks

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3 3D Steady and Transient Centrifugal Pump Flow within Ansys CFX and OpenFOAM

Authors: Clement Leroy, Guillaume Boitel


This paper presents a comparative benchmarking review of a steady and transient three-dimensional (3D) flow computations in centrifugal pump using commercial (AnsysCFX) and open source (OpenFOAM) computational fluid dynamics (CFD) software. In centrifugal rotor-dynamic pump, the fluid enters in the impeller along to the rotating axis to be accelerated in order to increase the pressure, flowing radially outward into another stage, vaned diffuser or volute casing, from where it finally exits into a downstream pipe. Simulations are carried out at the best efficiency point (BEP) and part load, for single-phase flow with several turbulence models. The results are compared with overall performance report from experimental data. The use of CFD technology in industry is still limited by the high computational costs, and even more by the high cost of commercial CFD software and high-performance computing (HPC) licenses. The main objectives of the present study are to define OpenFOAM methodology for high-quality 3D steady and transient turbomachinery CFD simulation to conduct a thorough time-accurate performance analysis. On the other hand a detailed comparisons between computational methods, features on latest Ansys release 18 and OpenFOAM is investigated to assess the accuracy and industrial applications of those solvers. Finally an automated connected workflow (IoT) for turbine blade applications is presented.

Keywords: Turbomachinery, Internet of Things, Benchmarking, CFX, openFOAM, time-accurate

Procedia PDF Downloads 85
2 Aeroelastic Stability Analysis in Turbomachinery Using Reduced Order Aeroelastic Model Tool

Authors: Chandra Shekhar Prasad, Ludek Pesek Prasad


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

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1 Computational Fluid Dynamics Simulation and Design Optimisation of a Triple Exit Volute for High Speed Centrifugal Compressor

Authors: Brett Peter Dewar


The key elements of a whole compressor system are inlet, impeller, diffuser, and volute. It is perhaps the volute that is the least well understood. Early simulation efforts have, justifiably, focused mostly on the impeller. As compressor speeds become higher, increased performance is demanded (particularly with regard to efficiency), and space, where compressors are housed, becomes tighter non-traditional volute designs are being studied. One such design is to have a volute with multiple outlets. Such a design has the potential to decrease the flow path length of individual fluid parcels from inlet to outlet, thus reducing total pressure loss for comparable static pressure rise. These designs also allow for the working fluid to be separated for different applications in the system as a whole, such as to different reservoirs, engine banks, or heat exchangers. These designs do, however, introduce more complicated geometry, particularly the addition of extra volute tongues; this can mitigate any gains in performance if the design is not carefully simulated and optimised. This works details the design, optimisation, and simulation process of a triple exit volute for a high speed air compressor. A detailed explanation of the CFD methodology is given, including boundary conditions and mesh verification. The volute geometry is evaluated in terms of different profile shapes and their hydraulic diameter gradient with regard to circumferential position. Cross section profiles are also allowed to change for each outlet, i.e., the design is not restricted to one volute simply mirrored three times. Objective functions are presented in terms of static pressure rise, total pressure loss, and circumferential velocity component at each cross section and compared against hydraulic diameter as a function of circumferential position. Finally, an analysis of any differences at the three volute tongues is presented.

Keywords: Turbomachinery, Computational Fluid Dynamics, Optimisation, ANSYS

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