Analysis of a Device for Generating Perturbations in Supersonic Wind Tunnels

Abstract

The analytical study of a device called the dual plate disturbance generator is described. This device has been proposedasa mechanism for generatinggustlike perturbations in supersonicwind tunnels. Thedevice is envisioned as a means to experimentally validatedynamicmodels and control systems designed for high-speed inlets. The dual platedisturbancegenerator is composedof two  at trapezoidalplates thatmodify theproperties of the  ow ingested by a supersonic inlet. One plate may be oscillated to generate small perturbations in the  ow. The other plate is held stationary to maintain a constant angle of attack. Four modes of operation exist; each mode is distinguished by the relative position of the plates and the structure of the resulting  owŽ eld. Design equations and performance maps were developed for one of the four modes of operation using an idealized approach and the compressible  ow relations. The maps and equations were then used to design and evaluate a disturbance generator for a 3.05 £ 3.05 m (10 £ 10 ft) supersonic wind tunnel. Results suggest that, under certain conditions, the proposed device canmeet and exceed established gust generator requirements. However, further study is required to identify the optimalmode of operation and establish feasibility.