Speed Line Computation of a Transonic Compressor Stage With Unsteady CFD Methods

Abstract

The flow through a transonic compressor stage is dominated by unsteady effects such as shock propagation and wake shedding. An accurate prediction of the performance of a compressor, i.e. operating range and efficiency, may require the modeling of unsteady effects. Steady CFD methods cease to converge too early when the stall limit is approached. Efficient unsteady CFD methods such as the transient time-inclining (TI) method and the perturbation based non-linear harmonic (NLH) method perform better and are becoming increasingly popular in the industry. Both methods consider the actual blade count ratio for each passage while using a single passage model. The main objective of this paper is to explain these methods and benchmark their performance with respect to reliable near stall predictions. Computed compressor characteristics and blade row interaction effects of the Purdue Transonic Research Compressor are compared to measurement data. The stator row is found to be limited at the casing in all of the unsteady simulation results. This effect is also qualitatively predicted by steady results calculated at a lower back pressure level. The NLH method is significantly faster than the other transient methods and the TI method resolves more flow detail on identical meshes.

URANS analysis of the effect of realistic inlet distortions on the stall inception of a centrifugal compressor

“…This is a second order cell-centered finite volume solver for structured multiblock meshes. The code was already successfully employed in different circumstances to represent unsteady flow patterns of tip loaded transonic axial and radial compressors operating at near stall conditions [18][19][20].…”

Assessment of the Severity of Unsteady Mach Number Effects in a 3-Stage Transonic Compressor

“…Some of these present results from multistage calculations but only at design speed [2][3][4][5] while others present results at offdesign speeds but only for a single stage [6]. Others compare steady and unsteady results but only for a single stage and at design speed [7][8][9]. Further single stage unsteady simulations have been presented for part speed calculations [10][11][12] and at design speed [13][14][15][16][17], including Large Eddy Simulations (LES) [18], however, none of these compare the unsteady simulations to steady simulations.…”

Application of the Time-Transformation Method for a Detailed Analysis of Multistage Blade Row Interactions in a Shrouded Turbine

“…In the literature the TT method has shown very promising results in terms of predicting turbo machinery performance data as Biesinger et al (2010) demonstrated by the example of a one stage case (inlet guide vane (IGV) and rotor) of the 1.5 stage transonic Purdue compressor and later on the full 1.5-stage case (Biesinger et al (2012)). Cornelius et al (2013Cornelius et al ( , 2014 investigated the multistage extension of the TT method on a modified 2.5-stage version of the 4-stage axial Hannover Compressor and a Siemens 6-stage axial compressor rig ("PCO Rig").…”