scholarly journals Unsteady flow investigations in an axial turbine using the massively parallel flow solver TFLO

2001 ◽  
Author(s):  
Jixian Yao ◽  
Roger Davis ◽  
Juan Alonso ◽  
Antony Jameson
Keyword(s):  
Unsteady Flow ◽  
Parallel Flow ◽  
Massively Parallel ◽  
Axial Turbine ◽  
Flow Solver

Effects of the Clocking on the Internal Flow in a 1.5 Stage Axial Turbine

2006 ◽  
Author(s):  
Jongil Park ◽  
Minsuk Choi ◽  
Jehyun Baek
Keyword(s):  
Unsteady Flow ◽  
Relative Efficiency ◽  
Message Passing Interface ◽  
Flow Simulation ◽  
Internal Flow ◽  
Leading Edge ◽  
Maximum Efficiency ◽  
Axial Turbine ◽  
Flow Solver ◽  
Local Efficiency

A three-dimensional unsteady flow simulation is conducted to investigate clocking effects of a row of stators on the performance and internal flow in a 1.5 stage axial turbine. Although the original turbine has 22 blades of the first stator, 28 blades of the rotor and 28 blades of the second stator, the first stator is reduced by a factor of 22/28 to fit the blade ratio 1:1:1. The unsteady flow solver is implemented using the second order time marching and sliding mesh scheme between blade rows. And then, this flow solver is parallelized using MPI (Message Passing Interface) libraries to overcome the limitation of memories and to save the calculation time. Six relative positions of two rows of stators are investigated by positioning the second stator being clocked in a step of 1/6 pitch. The relative efficiency benefit of about 1% is obtained depending on clocking positions. At mid-span, the first stator wake is mixed up with the rotor wake before arriving at the leading edge of the second stator. The time-averaged local efficiency along the span at the maximum efficiency shows more uniform distribution than that at the minimum efficiency. Moreover, the variation of local efficiency at the mid-span does not coincide with that of overall efficiency. Therefore, it is found in this case that the only wake trajectory of the first stator is not a proper means of predicting the best and worst efficiency positions. This is why the relative efficiency benefit depending on the clocking position is obtained near the hub and casing in this study. So, it is necessary to find a general cause of the clocking effect which is applicable to every test case. The difference between maximum and minimum instantaneous efficiencies during one period is found to be smaller at the maximum efficiency than at the minimum efficiency.

scholarly journals Development and Validation of a Massively Parallel Flow Solver for Turbomachinery Flows

2001 ◽  
Vol 17 (3) ◽  
pp. 659-668 ◽  
Author(s):  
Jixian Yao ◽  
Antony Jameson ◽  
Juan J. Alonso ◽  
Feng Liu
Keyword(s):  
Parallel Flow ◽  
Massively Parallel ◽  
Flow Solver ◽  
Development And Validation

Massively Parallel Simulation of the Unsteady Flow in an Axial Turbine Stage

2002 ◽  
Vol 18 (2) ◽  
pp. 465-471 ◽  
Author(s):  
Jixian Yao ◽  
Roger L. Davis ◽  
Juan J. Alonso ◽  
Antony Jameson
Keyword(s):  
Unsteady Flow ◽  
Parallel Simulation ◽  
Massively Parallel ◽  
Turbine Stage ◽  
Axial Turbine

Grid adaptation for unsteady flow computations

1997 ◽  
Vol 211 (4) ◽  
pp. 237-250 ◽  
Author(s):  
C B Allen
Keyword(s):  
Unsteady Flow ◽  
Unsteady Flows ◽  
Processing Unit ◽  
Flow Solver ◽  
Transfinite Interpolation ◽  
Central Processing ◽  
Grid Adaptation ◽  
Euler Flows ◽  
Adaptation Procedure ◽  
Grid Points

A grid adaptation procedure suitable for use during unsteady flow computations is described. Transfinite interpolation is used to generate structured grids for the computation of steady and unsteady Euler flows past aerofoils. This technique is well suited to unsteady flows, since instantaneous grid positions and speeds required by the flow solver are available directly from the algebraic mapping. A different approach to grid adaptation is described, wherein adaptation is performed by redistributing the interpolation parameters, instead of the physical grid positions. This results in the adapted grid positions, and hence speeds, still being available algebraically. Grid adaptation during an unsteady computation is performed continuously by imposing an ‘adaptation velocity’ on grid points, thereby applying the adaptation over several time steps and avoiding the interpolation of the solution from one grid to another, which is associated with instantaneous adaptation. For both steady and unsteady flows the adapted grid technique is shown to produce sharper shock resolution for a very small increase in CPU (central processing unit) requirements.

Predicting Bladerow Interactions Using a Multistage Time-Linearized Navier-Stokes Solver

2003 ◽  
Vol 125 (1) ◽  
pp. 25-32 ◽  
Author(s):  
W. Ning ◽  
Y. S. Li ◽  
R. G. Wells
Keyword(s):  
Unsteady Flow ◽  
Frequency Domain ◽  
Test Data ◽  
Computational Efficiency ◽  
Unsteady Flows ◽  
Navier Stokes ◽  
Test Cases ◽  
Numerical Accuracy ◽  
Flow Solver ◽  
Time Marching

A multistage frequency domain (time-linearized/nonlinear harmonic) Navier-Stokes unsteady flow solver has been developed for predicting unsteady flows induced by bladerow interactions. In this paper, the time-linearized option of the solver has been used to analyze unsteady flows in a subsonic turbine test stage and the DLR transonic counter-rotating shrouded propfan. The numerical accuracy and computational efficiency of the time-linearized viscous methods have been demonstrated by comparing predictions with test data and nonlinear time-marching solutions for these two test cases. It is concluded that the development of efficient frequency domain approaches enables unsteady flow predictions to be used in the design cycles to tackle aeromechanics problems.

scholarly journals Investigation of the Optimum Clocking Position in a Two-Stage Axial Turbine

2005 ◽  
Vol 2005 (3) ◽  
pp. 202-210 ◽  
Author(s):  
Dieter Bohn ◽  
Sabine Ausmeier ◽  
Jing Ren
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Preliminary Design ◽  
Two Stage ◽  
Axial Turbine ◽  
Sliding Mesh ◽  
Field Distributions ◽  
Unsteady Simulation

A frozen rotor approach in a steady calculation and a sliding mesh approach in an unsteady simulation are performed in a stator clocking investigation. The clocking is executed on the second stator in a two-stage axial turbine over several circumferential positions. Flow field distributions as well as the estimated performances from two approaches are compared with each other. The optimum clocking positions are predicted based on the estimated efficiency from the two approaches. The consistence of the optimum clocking positions is discussed in the paper. The availability and the limit of the frozen rotor approach in predicting the optimum clocking position is analyzed. It is concluded that the frozen rotor approach is available to search the optimum clocking position in the preliminary design period, although it misses some features of the unsteady flow field in the multistage turbines.

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