Numerical investigation into the mechanism regarding the inception and evolution of flow unsteadiness induced by the tip leakage flow in a transonic compressor

Abstract

Unsteady flow in the blade tip region of modern axial flow compressors is one of the sources of loss, noise, and blade vibration. In some cases, it is potentially linked to stall inception. In this paper, the complex flow fields in the blade tip region of a transonic axial flow compressor rotor have been numerically investigated. The predicted results were validated by experimental data. Analyses of monitoring results of numerical probes showed that three typical flow characteristics occurred as the operating condition approached the stability limit: no flow fluctuation at the first operating point; flow fluctuation with high frequency and low amplitude at the second operating point; flow fluctuation with low frequency and high amplitude at the third operating point. Further analysis of the tip flow field showed that the evolution of the tip leakage vortex experienced three stages as the rotor was throttled. At the first stage, the TLV did not breakdown. At the second stage, a bubble-type breakdown of the tip leakage vortex occurred. At the third stage, a spiral-type breakdown of tip leakage vortex occurred. The current study demonstrated that the flow unsteadiness that appears within the test rotor was induced by the tip leakage vortex breakdown. Furthermore, with the transformation of the vortex breakdown form, the characteristic frequency and amplitude of the flow oscillation substantially changed.

Effect of hub clearance of cantilever stator on aerodynamic performance and flow field of a transonic axial-flow compressor

“…It is showed that the total pressure ratio was generally lower than the test results, which might be explained by the difference in data processing between the experimental and numerical methods, and was consistent with the comparisons of other researchers. 22 On the whole, the overall trend of the curves obtained by numerical calculation is in good agreement with the experimental dates. Figure 5 further shows the comparison between the numerical and experimental radial distribution of the total pressure ratio and total temperature ratio at the compressor outlet at the peak efficiency point (PEP) and near stall point (NSP).…”

Analysis of circumferential gas force on star-wheel in a single screw expander

“…This assumption is also widely used in air/ refrigerant compressors and expanders. 15,25 The flow field obeys mass conservation equation and momentum conservation equation. In addition, the air velocity is high and the pressure difference between the inlet boundary and outlet boundary is large, then, the density of the air significantly changes when the air passes through the gap, therefore, the energy conservation equation should be considered.…”

Combination resonance and primary resonance characteristics of a dual-rotor system under the condition of the synchronous impact of the inter-shaft bearing

“…Soderquist et al 13 explained the connections between the variations in circumferential rotor power and the inlet total pressure distortion, pressure-induced swirl, total pressure distortion transfer, and total temperature distortion production. An et al 14 used numerical analysis to examine the complicated flow fields in a transonic axial flow compressor rotor's blade tip area, and the characteristic frequency and amplitude of the flow oscillation showed a significant shift with the modification of the vortex breakdown shape.…”