Supporting System Study of Wind-Tunnel Models for Validation of Aft-Sonic-Boom Shaping Design

Abstract

Study on supporting system of wind-tunnel models for validating aft-sonic-boom shaping design technology is conducted in transonic wind-tunnel using several wind-tunnel models which are designed for low-boom. Two types of model supporting systems, a single sting and a twin sting support, are tested. Among these supporting systems for measuring near-field pressure signatures of a model, the twin sting support seems to be a promising system for validating some aft-sonic-boom shaping design concepts which are applied to the aft-part of an airplane, such as an aft-fuselage, engine nacelles and tail wings. The measured pressure data are also used to validate the low-boom design method based on the equivalent area theory and a near-field pressure prediction tool. I. Introduction UPERSONIC passenger aircrafts are promising for future airliners with the possibilities to meet the growing airlift demand and to liberate passengers from the pain due to long flight time. Various difficulties, however, prevent the civil aircrafts from flying at supersonic speeds after the Concorde’s retirement in 2003: The economically viable (low-weight, low-drag and high-efficient propulsion) and the environmentally friendly (lowsonic-boom, low-noise and low-emissions) characteristics are required for future supersonic airliners. Above all, sonic-boom is one of the most serious problems to be solved for supersonic overland flight. The Silent SuperSonic (S-cube) research program on quiet supersonic aircraft design technologies started in 2006 at Japan Aerospace Exploration Agency (JAXA). In this program, the Silent SuperSonic Technology Demonstrator (S 3 TD) [1] is planned to be built in order to demonstrate the advanced low-sonic-boom design technologies; low-boom design concepts and design/analysis tools. Recently, some flight demonstration programs for some low-boom design technologies have been conducted and they have shown some remarkable progresses [2-4]. The effectiveness of low-boom design technologies should be finally validated through these kinds of flight demonstrations. Meanwhile wind-tunnel test is still meaningful in the technology validation, at least in a preliminary phase of the flight demonstration programs. The wind-tunnel testing, however, have some problems in model supporting methods which have an influence on measuring near-field pressure signatures for validating the low-boom design concepts in particular the aft-part of signatures [5]. A windtunnel model designer should take into account these model/sting interference. This paper mainly discusses the wind-tunnel testing techniques especially the model supporting systems for validating the aft-sonic-boom shaping concepts and design. A twin-sting supporting system as well as a conventional single-sting supporting system is used in this study in order to show the possibility of validating aftsonic-boom shaping concepts. Aft-low-boom design concept and design tools are examined through the comparison between numerical prediction and wind-tunnel test data. The possibility of boom-shielding effect is also examined in this wind-tunnel test.