Session: 40-03 Compressor Flow and Interaction Effects

Submission Number: 179365

An Investigation Into Optimal Reduced Frequency of Wakes at Low Reynolds Number Using an Experimentally Simulated Axial Compressor Blade 

The flow over axial compressor blade suction surfaces are typically subject to adverse pressure gradients. When operating at low Reynolds Numbers they are prone to separated flow transition. The separation region causes larger losses through momentum deficit and therefore a reduction in overall efficiency. The impinging upstream wakes influence the transition process over the periodically supressed separation region. The experimental data from Particle Image Velocimetry measurements conducted at three reduced frequencies, 0.64,1.28 and 2.56, are explored in this study to understand the existence of an optimum value for this parameter where losses are at a minimum. The Renolds number is held the same for all cases at 210,000. For each case, the turbulent kinetic energy (TKE) at six equally spaced time intervals within the wake-cycle are analysed and are spatially and temporally averaged to reveal a trend. High levels of TKE are found for low reduced frequencies where the TKE is generated through the relatively large separated region that exists. High levels of TKE is also observed at the highest reduced frequency, but this time due to the ‘sustained’ presence wake turbulence while the separation remains continuously supressed. The intermediate reduced frequency case is observed to have lower total TKE where the separated region is small and the interval between the wake induced turbulence is sufficiently large. This gives rise to the possibility of an optimal reduced frequency for a given Reynolds number and blade loading (adverse pressure gradient) condition.

Presenting Author: Thomas Irps University of Sussex

Presenting Author Biography: Thomas Irps is a final year postgraduate research student at the Thermo-Fluid Mechanics Research Centre at he Univerisity of Sussex.

Authors:

Thomas Irps University of Sussex
Vasudevan Kanjirakkad University of Sussex