Forward Flight Effects on Counterflow Thrust Vector Control of a Supersonic Jet

Abstract

Introduction T HE beneŽ ts of active thrust vector control in high-performance Ž ghter aircraft, such as improved agility and maneuverability, are well established. Unfortunately, conventional thrust vectoring schemes, which rely on mechanical means to vector the jet thrust, have some associated drawbacks. They generally require complicated hardware, which can add to the aircraft weight; the dynamic performance of such systems is less than ideal; and there are heat transfer problems due to the hot exhaust jet impinging on the vectoring surface. Although recent advances have been made in improving mechanical systems, some of the mentioned issues remain a concern. In recent years, a  uidic-based thrust vectoring technique, counter ow thrust vector control (CFTVC), has been exploredwith promising results.2i4 These investigationshave convincingly demonstrated that CFTVC can be used to achieve single-axis pitch vectoring and multiaxis thrust vectoring for supersonic nozzles of various geometries and over a wide range of operating conditions. One of the primary advantages of CFTVC is the simplicity of hardware and excellent dynamic response. A comprehensive summary of these studies can be found in Refs. 2 and 4. The ultimate goal of our researchprogramis to developa CFTVC system that can be implemented in aircraft propulsion systems of the future. To this end one needs to consider real  ight effects, such as high jet exhaust temperatures and the in uence of forward  ight. Although high-temperatureeffects have been addressed to a limited extent in a previous investigation, almost nothing is known about forward  ight effects on CFTVC performance. In the present study, forward  ight effectsare simulatedby generatinga co owing stream around the periphery of the CFTVC system consisting of a rectangular Mach 1.4 jet. The in uence of the co owing stream on the system performance in terms of jet vector angle response is described in this Note.