Flow Disturbance by Intrusive Instrumentation: Part 1 – Protrusions on the Pressure Side of HP Compressor Vanes

In this study, we quantify the aerodynamic impact of spanwise pressure tubes located on the pressure side of a high-pressure compressor stator vane. We conducted experiments in a linear cascade wind tunnel (Mach number ∼0.5, Reynolds number 790,000) by modeling the pressure tubes as simplified protrusions with varying dimensions. Testing eight configurations with protrusion heights of 33% and 66% of the maximum vane thickness and a protrusion width ranging from 8% to 24% of the chord length reveals that narrow, as well as high, protrusions increase the total pressure loss the most. Therefore, the narrowest and highest protrusion configuration increases the loss by a factor of 4.7 compared to a vane without a protrusion, while the widest and flattest protrusion increases the loss by a factor of 1.2. Oil flow visualization and CFD simulations reveal that narrow and high protrusions lead to separation-induced losses. The study offers insights for test engineers who are responsible for designing compressor vane instrumentation to minimize additional total pressure loss.