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 flow applications. Tunnel operating conditions were chosen to focus specifically 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 fluid flows. This technique is used to measure the instantaneous velocity field in a vertical plane close to the intake. The flow processes important to ingestion (fountain flow, ground vortex, intake suction) are all captured. The large-scale unsteadiness of the ingestion events are studied and quantified. For the present jet-discharge/intake configuration, 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