Particle Image Velocimetry for Intake Ingestion in Short Takeoff and Landing Aircraft

Abstract

Exhaust gas ingestion can cause many major problems for a short takeoff and vertical landing (STOVL) aircraft operating in ground effect, for example, engine surge. As part of a program of experimental and computational work on intake ingestion problems, a generic twin jet discharge/intake model was designed, constructed, and tested in a water tunnel especially designed for STOVL ow applications. Tunnel operating conditions were chosen to focus speci cally on the intake ingestion process. Particle image velocimetry (PIV) has now been developed into a well-established technique that can provide two-dimensional spatially resolved velocity measurements in complex uid ows. This technique is used to measure the instantaneous velocity eld in a vertical plane close to the intake. The ow processes important to ingestion (fountain ow, ground vortex, intake suction) are all captured. The large-scale unsteadiness of the ingestion events are studied and quanti ed. For the present jet-discharge/intake con guration, PIV is demonstrated as capable of producing quantitative information on instantaneous eddy structure and its temporal development, which is essential to improving our understanding of the exhaust gas ingestion phenomenon.

The application of laser measurement techniques to aerospace flows

“…PIV results showed the presence of a large unsteady ground vortex which moved along the surface by up to four nozzle diameters. Related work was also completed by Behrouzi and McGuirk [121] on an incompressible impinging water jet and similar transient ground vortex characteristics were observed.…”