Development of a transonic wind tunnel test bed for MEMS flow control actuators and sensors

One of the main limiting technological hurdles in the application of flow control is now seen to be in the flight readiness of the required actuator and sensor hardware. This paper outlines the setting up and running of a facility for evaluating novel flow control actuator and sensor hardware under conditions representative of near flight scale Mach number and Reynolds number. The facility provides a necessary bridge between low cost bench top/ low speed wind tunnel experiments on MEMS devices and high cost flight tests. The primary value of the facility is in validating the functionality of MEMS sensors and actuators when installed in representative packaging and exposed to external aerodynamic conditions consistent with industrial application. Discovery of novel flow physics associated with actuated transonic flows is not an expressed aim of the facility, however experiments are conducted in a manner such that meaningful quantitative results can be used to evaluate the validity of flow control actuator mechanisms developed based on low speed tunnel tests. Testing takes place in the University of Manchester 0.15×0.20m Transonic Wind Tunnel at a maximum Mach number of 0.8. The main focus is on testing MEMS hot film sensors for use as boundary layer state detectors (laminar/transitional/ turbulent) and pulsed air jet vortex generators as a means of forced boundary layer mixing for separation control applications. The facility has so far been used to establish laminar/transitional/turbulent flow on a flat plate with zero pressure gradient at M=0.8. The maximum test Reynolds numbers associated with the laminar and turbulent flow test regions are 2×105 and 2×106 respectively. Boundary layer state has been successfully measured using both commercial glue on hot film probes and industrial prototype MEMS devices. Copyright © 2009 by The University of Manchester.