Simulations of the Unsteady Flow Through the Fastrac Supersonic Turbine (original) (raw)
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Unsteady Flow Analysis of a Highly Loaded High-Pressure Turbine of a Gas Turbine Engine
Proceedings of the National Aerospace Propulsion Conference, 2020
Advanced fighter aircraft requires a gas turbine engine with high thrust to weight ratio of the order 10 and low specific fuel consumption of the order 0.7 (kg/kghr) to meet the high maneuverability, long range, and low life cycle cost requirements. To meet high thrust to weight ratio and low specific fuel consumption, aero gas turbine engine demands high turbine entry temperature and high turbine efficiency. In order to reduce design cycle time typically, a turbo machinery design process is carried out with the assumption that the flow is steady. However, the fluid flow in turbo machinery is highly three-dimensional and inherently unsteady due to stator-rotor interactions through wakes, potential flow, and shock interactions. In this paper, an attempt is made to analyze the unsteady flow in a transonic High-Pressure (HP) turbine which is having high blade loading and low aspect ratio, and is designed for an advanced engine. The calculations are performed by using ANSYS-CFX, which is a commercial software. This software solves three-dimensional Navier-Stokes equations. Structured grids are used in this analysis and turbulence is modeled by using k-ω SST turbulence model. Sliding interface models are used for unsteady simulation studies to analyze the flow field of the turbine stage. Numerical study shows that total-to-total efficiency of the HP turbine stage decreases by 0.4% due to unsteadiness as compared to steady state.
Computational Analysis of Unsteady Flow in a Partial Admission Supersonic Turbine Stage
Volume 2D: Turbomachinery, 2014
Turbines used in upper stage engine for a rocket are sometimes designed as a supersonic turbine with partial admission. This study deals with numerical investigation of supersonic partial admission turbine in order to understand influences on the unsteady flow pattern, turbine losses and aerodynamic forces on rotor blades due to partial admission configuration. Two-dimensional CFD analysis is conducted using "Numerical Turbine" code. Its governing equation is URANS (Unsteady Reynolds Averaged Navier-Stokes Simulation) and fourth-order MUSCL TVD scheme is used for advection scheme. The unsteady simulation indicates that strongly nonuniform circumferential flow field is created due to the partial admission configuration and it especially becomes complex at 1 st stage because of shock waves. Some very high or low flow velocity regions are created around the blockage sector. Nozzle exit flow is rapidly accelerated at the inlet of blockage sector and strong rotor LE shock waves are created. In contrast, at rotor blade passages and Stator2 blade passages existing behind the blockage sector, working gas almost stagnates. Large flow separations and flow mixings occur because of the partial admission configuration. As a result, additional strong dissipations are caused and the magnitude of entropy at the turbine exit is approximately 1.5 times higher than that of the full admission. Rotor1 blades experience strong unsteady aerodynamic force variations. The aerodynamic forces greatly vary when the Rotor1 blade passes through the blockage inlet region. The unsteady force in frequency domain indicates that many unsteady force components exist in wide frequency region and the blockage passing frequency component becomes pronounced in the circumferential direction force. Unsteady forces on Rotor2 blades are characterized by a low frequency fluctuation due to the blockage passing.
Theoretical analyses and computer codes are being developed under Contract NAS3-25425 for predicting compressible unsteady inviscid and viscous flows through blade rows. be developed to provide a useful unsteady viscous aerodynamic analysis for realistic cascade configurations. PRECEDING PAGE BLANK NOT FILMED Dring et al. [14, 15]. These were found to be in good agreement with previous analytical and numerical solutions for flat-plate airfoils and with the experimental results for the turbine cascades. 1.1 Scope of the Present Effort The objective of the research program being conducted under Contract NAS3-25425 is to provide efficient theoretical analyses for predicting compressible unsteady flows through two-dimensional blade rows. Such analyses are needed to understand the impact of unsteady aerodynamic phenomena on the aeroelastic and aeroacoustic performance of the blading. The work being conducted under this contract is directed primarily towards low-speed aeroelastic applications, however, for the most part it will apply more generally to the aeroelastic and 4. TITLE AND SUBTITLE Development of Unsteady Aerodynamic Analyses for Turbomachinery Aeroelastic and Aeroacoustic Applications
Numerical Unsteady Aerodynamics for Turbomachinery Aeroelasticity
UNSTEADY AERODYNAMICS, AEROACOUSTICS AND AEROELASTICITY OF TURBOMACHINES, 2000
This paper presents ONERA's recent advances in the experimental and numerical understandings about the aeroelastic stability of aeronautical turbomachineries. Numerical features of a quasi-3D and a 3D Navier-Stokes unsteady aeroelastic solver are discussed: turbulence models, grid deformation techniques, specific boundary conditions, dual time stepping. A dynamically coupled fluidstructure numerical scheme is presented. Isolated profile, rectilinear cascades computational results are compared to experimental data. Results of aeroelastic Navier-Stokes computations for 3D fans are shown.
Assessment of Turbocharger Turbine Unsteady Flow Modelling Methodology on Engine Performance
Volume 1: Applied Mechanics; Automotive Systems; Biomedical Biotechnology Engineering; Computational Mechanics; Design; Digital Manufacturing; Education; Marine and Aerospace Applications, 2014
Although it is well known that the flow entering a turbine of a turbocharger engine is highly unsteady, engine manufacturers prefer to use turbine performance predictions that are based on steady-state performance maps, which inherently lead to inaccuracies in the turbine's behavior and mismatches between turbocharger turbines and engines. The reason for this preference is due to the turbocharger turbine design software that are generally available to engine manufacturers being based on and compatible with steady-state performance maps and this fact led researchers to investigate how the inaccuracies of this steady-state treatment of the turbine can be alleviated.
Unsteady Aerodynamic Models for Turbomachinery Aeroelastic and Aeroacoustic Applications
1995
Theoretical analyses and computer codes have been developed for predicting compressible the three analyses axe demonstrated via applications to unsteady flows through compressor and turbine cascades. The numerical results pertain to unsteady flows excited by prescribed vortical disturbances at inlet, acoustic disturbances at inlet and exit and blade bending and torsional vibrations. Recommendations axe also given for the future research needed for extending and improving the foregoing asymptotic analyses, and to meet the goal of providing an efficient inviscid/viscid interaction capability for subsonic and transonic unsteady cascade flOWS.
Volume 1: Advances in Aerospace Technology; Energy Water Nexus; Globalization of Engineering; Posters, 2011
A computational validation study related to aerodynamic loss generation mechanisms is performed in an axial flow turbine nozzle guide vane (NGV). The 91.66 cm diameter axial flow turbine research facility has a stationary nozzle guide vane assembly and a 29 bladed HP turbine rotor. The NGV inlet and exit Reynolds numbers based on midspan axial chord are around 300000 and 900000, respectively. The effect of grid structure on aerodynamic loss generation is investigated. GAMBIT and TGRID combination is used for unstructured grid, whereas GRID-PRO is the structured grid generator. For both cases, y + values are kept below unity. The finite-volume flow solver ANSYS CFX with SST k −ω turbulence model is employed. Experimental flow conditions are imposed at the boundaries. The flow transition effect and the influence of corner fillets at the vane-endwall junction are also studied in this paper. Grid independence study is performed with static pressure coefficient distribution at the midspan of the vane and the total pressure coefficient at the NGV exit. The velocity distributions and the total pressure coefficient at the NGV exit plane are in very good agreement with the experimental data. This validation study shows that the effect of future geometrical modifications on the endwalls and the vane will be predicted reasonably accurately. The current study shows that an accurately measured turbine stage geometry, a properly prepared block structured/body fitted grid, a state of the art transitional flow implementation, and realistic boundary conditions