Session: 05-07 Topics in Instrumentation (III)

Paper Number: 83152

83152 - Response of Separated Boundary Layers to Steady and Pulsated Flow Injection in Transonic Internal Flows 

A new class of power generation of devices are emerging that experience increased losses due to bulk flow separation in segments of their expected in-flight regime. As such, active flow control becomes increasingly relevant to mitigate these losses and reclaim the full flight envelope. This study explores the effect of flow injection on transonic flows experiencing bulk separation. Reynolds-Averaged Navier-Stokes simulations of a 3D wall-mounted hump at low Reynolds numbers are conducted to assess the response of transonic bulk separation to flow injection. Unsteady simulations are conducted to understand the differences between slot and discrete port injection and to determine optimum forcing frequencies. Discrete ports require higher pressures to overcome the momentum deficit associated with the smaller injection area relative to the width of the domain. Steady and unsteady are found as viable strategies in mitigating the extent (or appearance) of bulk separation. Experiments are conducted with discrete injection for a range of Mach numbers and Reynolds numbers. The response of the bulk separation to said injection is evaluated by analyzing both local pressure measurements and schlieren imaging. The study shows that the required mass flow injection is strongly correlated to the length scale of the uncontrolled separation. The optimal Strouhal number, based on inlet quantities and the length scale of the uncontrolled separation, and total pressure ratios of injection are presented for a range of Reynolds and Mach numbers. This study aims to establish guidelines for application of flow control to the emerging class of power generation devices experiencing losses from bulk separation.

Presenting Author: Hunter Nowak Purdue Experimental Turbine Aerothermal Lab

Presenting Author Biography: Hunter is a graduate student working at the Purdue Experimental Turbine Aerothermal Lab. He worked as a co-op student with GE Aviation in his undergraduate career in test infrastructure engineering, among others.

Authors:

Hunter Nowak Purdue Experimental Turbine Aerothermal Lab
Federico Lluesma-Rodriguez Universitat Politècnica de València
Iman Rahbari Purdue University
John Clark U.S. Air Force Laboratory
Guillermo Paniagua Purdue University