Closure to “Discussions of ‘Mixing in Axial-Flow Compressors: Conclusions Drawn From Three-Dimensional Navier–Stokes Analyses and Experiments’” (1991, ASME J. Turbomach., 113, pp. 156–158)

Extensive numerical analyses and experiments have been conducted to understand mixing phenomena in multistage, axial-flow compressors. For the first time in the literature the following are documented: Detailed three-dimensional Navier–Stokes solutions, with high order turbulence modeling, are presented for flow through a compressor vane row at both design and off-design (increased) loading; comparison of these computations with detailed experimental data show excellent agreement at both loading levels; the results are then used to explain important aspects of mixing in compressors. The three-dimensional analyses show the development of spanwise (radial) and circumferential flows in the stator and the change in location and extent of separated flow regions as loading increases. The numerical solutions support previous interpretations of experimental data obtained on the same blading using the ethylene tracer-gas technique and hot-wire anemometry. These results, plus new tracer-gas data, show that both secondary flow and turbulent diffusion are mechanisms responsible for both spanwise and circumferential mixing in axial-flow compressors. The relative importance of the two mechanisms depends upon the configuration and loading levels. It appears that using the correct spanwise distributions of time-averaged inlet boundary conditions for three-dimensional Navier–Stokes computations enables one to explain much of the flow physics for this stator.

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Aerodynamic Design Optimization of an Axial Flow Compressor Rotor

Volume 5: Turbo Expo 2002, Parts A and B ◽

10.1115/gt2002-30445 ◽

2002 ◽

Cited By ~ 13

Author(s):

Chan-Sol Ahn ◽

Kwang-Yong Kim

Keyword(s):

Design Optimization ◽

Response Surface ◽

Computing Time ◽

Flow Analysis ◽

Three Dimensional ◽

Axial Flow ◽

Navier Stokes ◽

Transonic Compressor ◽

Compressor Rotor ◽

Design Variables

Design optimization of a transonic compressor rotor (NASA rotor 37) using the response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. The Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. It was found that the optimization process provides reliable design of a turbomachinery blade with reasonable computing time.

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Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

Journal of Turbomachinery ◽

10.1115/1.2840941 ◽

1996 ◽

Vol 118 (4) ◽

pp. 835-843 ◽

Cited By ~ 4

Author(s):

B. V. Marathe ◽

B. Lakshminarayana ◽

Y. Dong

Keyword(s):

Flow Field ◽

Secondary Flow ◽

Numerical Investigation ◽

Three Dimensional ◽

Axial Flow ◽

Torque Converter ◽

Operating Conditions ◽

Navier Stokes ◽

Complex Flow ◽

Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

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Kinematic Analysis of 3-D Swept Shock Surfaces in Axial Flow Compressors

Journal of Turbomachinery ◽

10.1115/1.1370159 ◽

2000 ◽

Vol 123 (3) ◽

pp. 490-500 ◽

Cited By ~ 2

Author(s):

Peng Shan

Keyword(s):

Three Dimensional ◽

Axial Flow ◽

Leading Edge ◽

Research Field ◽

High Loading ◽

Kinematic Characteristic ◽

Sweep Angle ◽

Quantitative Classification ◽

Axial Flow Compressors ◽

Blade Leading Edge

This paper is part II of a comprehensive study on the blade leading edge sweep/bend of supersonic and transonic axial compressors. The paper explores and analyzes the kinematic characteristic variables of three-dimensional (3-D) swept shock surfaces. In the research field studying the sweep aerodynamics of axial flow compressors and fans, many types of high loading swept blades are under intensive study. So, in both direct and inverse design methods and experimental validations, an accurate grasp of the sweep characteristic of the blade’s 3-D swept shock surface becomes of more concern than before. Associated with relevant blading variables, this paper studies the forward and zero and backward sweeps of shock surfaces, defines and resolves every kind of useful sweep angle, obtains dimensionless sweep similarity factors, suggests a kind of method for the quantitative classification of 3-D shock structures, and proposes the principle of 3-D shock structure measurements. Two rotor blade leading edge shock surfaces from two high loading single stage fans are analyzed and contrasted. This study is the foundation of the kinematic design of swept shock surfaces.

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Influences of Axial Gap Between Blade Rows on Secondary Flows and Aerodynamic Performance in a Turbine Stage

Volume 7: Turbomachinery, Parts A and B ◽

10.1115/gt2009-59855 ◽

2009 ◽

Cited By ~ 6

Author(s):

K. Yamada ◽

K. Funazaki ◽

M. Kikuchi ◽

H. Sato

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Axial Flow ◽

Axial Direction ◽

Secondary Flows ◽

Navier Stokes ◽

Turbine Stage ◽

Stator Vane ◽

Is Design ◽

Probe Measurements

A study on the effects of the axial gap between stator and rotor upon the stage performance and flow field of a single axial flow turbine stage is presented in this paper. Three axial gaps were tested, which were achieved by moving the stator vane in the axial direction while keeping the disk cavity constant. The effect of the axial gap was investigated at two different conditions, that is design and off-design conditions. The unsteady three-dimensional flow field was analyzed by time-accurate RANS (Reynolds-Averaged Navier-Stokes) simulations. The simulation results were compared with the experiments, in which total pressure and the time-averaged flow field upstream and downstream of the rotor were obtained by five-hole probe measurements. The effect of the axial gap was confirmed in the endwall regions, and obtained relatively at off-design condition. The turbine stage efficiency was improved almost linearly by reducing the axial gap at the off-design condition.

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Three-dimensional unsteady Navier—Stokes analysis of stator—rotor interaction in axial-flow turbines

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/0957650001537813 ◽

2000 ◽

Vol 214 (1) ◽

pp. 13-22 ◽

Cited By ~ 32

Author(s):

L He

Keyword(s):

Three Dimensional ◽

Axial Flow ◽

Navier Stokes ◽

Time Stepping ◽

Finite Volume Discretization ◽

Dual Time Stepping ◽

Passage Vortex ◽

Speed Up ◽

Time Marching ◽

Grid Technique

A three-dimensional full Navier-Stokes method is developed and applied to calculations of unsteady flows through multiple blade rows in axial-flow turbomachinery. The solver adopts the cellcentred finite volume discretization and the four-stage Runge-Kutta time-marching scheme. Unsteady calculations are effectively accelerated by using a time-consistent multi-grid technique, resulting in a speed-up by a factor of 10–20 with adequate temporal accuracy. The computational efficiency and validity of the present multi-grid technique are illustrated by comparisons with the results of the conventional dual time-stepping scheme. Calculated unsteady pressures on blade surfaces for a turbine stage performances at different stator-rotor axial gaps reveals a marked three-dimensional behaviour of the interaction between incoming wakes and rotor passage-vortex structures. The time-averaged losses from unsteady calculations show a noticeable spanwise redistribution compared with the steady results. Two dimensional and three-dimensional calculations indicate opposite trends in stage efficiency variation when the stator—rotor gap is reduced.

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