Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

Suryavamshi, N.; Lakshminarayana, B.

doi:10.1115/91-gt-222

Cited by 3 publications

(1 citation statement)

References 12 publications

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“…Experimental and numerical research to date has examined the mean velocity profile, the turbulence parameters, the wake decay and mixing rates, as well as the wake recovery under different parameter settings, such as blade loading, free-stream turbulence, rotation, etc. [1][2][3][4][5][6][7] Most of the experimental data have been obtained by single-point measurement, such as tri-axial hot-wire, split hot-film probes, five hole pitot tube, high response pressure transducer, and laser Doppler velocimetry. [1][2][3][4][5][6] The ability to examine the flow structure has improved significantly with the introduction of PIV ͑particle image velocimetry͒.…”

Section: Introductionmentioning

confidence: 99%

Decomposition of the spatially filtered and ensemble averaged kinetic energy, the associated fluxes and scaling trends in a rotor wake

et al. 2005

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Particle image velocimetry data obtained in the rotor wake of a turbomachine are used for examining elements of the ensemble averaged and spatially filtered kinetic energy. These two distinct averaging processes decompose the kinetic energy into four parts, consisting of the mean-flow resolved, mean-flow subgrid, fluctuating resolved, and fluctuating subgrid parts. Their evolution equations include energy flux terms among these parts. The results elucidate the fundamental difference between the filtered turbulence ͑Reynolds͒ production and the ensemble averaged subgrid scale ͑SGS͒ dissipation rates. Each of these terms consist of three energy fluxes, but only one of them is common to both, the flux from the mean-flow resolved to the fluctuating subgrid kinetic energy parts. The other two elements of the SGS dissipation are the fluxes from the mean-flow resolved to the mean-flow subgrid parts and the fluctuating resolved to the fluctuating subgrid parts. Likewise, the other two contributions to the turbulence production are the fluxes from the mean-flow resolved to the fluctuating resolved parts and the mean-flow subgrid to the fluctuating subgrid parts. In order to examine the decay rates of the kinetic energy parts throughout the rotor wake, a new method for determining the scaling parameters is introduced. The mean-flow resolved and subgrid parts scale with the modified velocity defect squared, but the decay rates of the turbulence parts are slower.

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Section: Introductionmentioning

confidence: 99%

Decomposition of the spatially filtered and ensemble averaged kinetic energy, the associated fluxes and scaling trends in a rotor wake

et al. 2005

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Wake Decay: Effect of Freestream Swirl

Brookfield

Waitz

Sell

1997

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery

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A study of the effects of freestream swirl on the decay characteristics of wakes shed from a rotating blade row is presented. The freestream swirl behind the rotor causes the wakes to skew tangentially, stretching the wakes as they are convected from the rotor to the stator. The effect of stretching on wake decay is illustrated using a simplified two-dimensional model. The model is described and the results are compared to 1) measurements from a two-dimensional cascade facility where no stretching or skewing of the wakes occurs, 2) solutions obtained using a three-dimensional, Reynolds-averaged Navier-Stokes solver, and 3) experimental wake measurements taken behind a low hub-to-tip ratio fan. For typical fan geometries with hub-to-tip ratios of approximately 0.5 and rotor-stator spacings of one to two rotor chord lengths, the wake can be stretched by over 50 percent. The stretching increases the mixing rate which leads to a reduction in the mean wake velocity deficit of approximately thirty percent and a widening of the wake of about fifteen percent. These effects account for much of the difference seen between cascade wake measurements and those taken behind rotating fan blade rows. It is therefore important to include such effects when using cascade data for prediction of fluid mechanic, acoustic, or structural phenomena associated with fan wakes. Finally, the study also suggests a potential for small (< 3 dB) reductions in wake-stator interaction noise through tailoring the fan loading distribution to produce particular span wise wake decay characteristics.

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Aerodynamic modelling of multistage compressor flow fields Part 1: Analysis of rotor-stator-rotor aerodynamic interaction

Hall¹

1998

Proceedings of the Institution of Mechanical Engineers, Part G:

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The primary purpose of this study was to investigate improved numerical techniques for predicting flows through multistage compressors. The vehicle chosen for this study was the Pennsylvania State University Research Compressor (PSRC). The PSRC facility consists of a 3 1/2-stage axial flow compressor which shares design features which are consistent with embedded stages of modern gas turbine engine axial flow compressors. In Part 1 of this two-part paper, several computational fluid dynamics techniques were applied to predict both steady and unsteady flows through the PSRC facility. Interblade row coupling via a circumferentially averaged mixing-plane approach was employed for steady flow analysis. A mesh density sensitivity study was performed to define the minimum mesh requirements necessary to achieve reasonable agreement with the experimental data. Time-dependent flow predictions were performed using a time-dependent interblade row coupling technique. These calculations evaluated the aerodynamic interactions occurring between rotor 2, stator 2 and rotor 3 for the PSRC rig.

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Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

Cited by 3 publications

References 12 publications

Decomposition of the spatially filtered and ensemble averaged kinetic energy, the associated fluxes and scaling trends in a rotor wake

Decomposition of the spatially filtered and ensemble averaged kinetic energy, the associated fluxes and scaling trends in a rotor wake

Wake Decay: Effect of Freestream Swirl

Aerodynamic modelling of multistage compressor flow fields Part 1: Analysis of rotor-stator-rotor aerodynamic interaction

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