Passive Flow Separation Control in Linear Compressor Cascade

Losses reduction is one of the main targets in modern compressors. In this article, the passive separation-controlled technique has been used to reduce the losses through six NACA 65-009 linear compressor cascade blades. Among passive techniques, the arced diverge -converge slot passes were grooved from the blade pressure side (P-S) to its suction side (S-S). Here, the slot height in the span-wise direction was selected to be 0.08 of the blade heights from End-wall side. The current work was performed experimentally and numerically at inlet flow conditions of Reynolds number $\mathrm{R}_{\mathrm{e}\mathrm{c}}=2.98\times 10^{5}$ and incidence angle $\mathrm{i}=4^{\circ}$. The experimental work was done to get the inlet velocity profile needed to initiate the solution of the numerical work. The five-hole probe was used to measure the flow parameters in the experimental part. The accuracy and the mesh independent were tested for numerical work. There was good agreement in results about velocity profiles and total pressure in the blade downstream between experimental and numerical solutions, even the numerical using $\mathrm{K}-\omega$-SST turbulence model provided higher values of total pressure losses. It was concluded that the use of a slotted blade able to reduce the total pressure losses coefficient by 40.5%, increasing the flow turning angle by 20.3% and increase the static pressure coefficient by 8.7 % near the end-wall.