Sonic boom alleviation using keel configurations
Conference Paper
Overview
Overview
abstract
This paper summarizes a detailed investigation of the application of off-axis volume control for sonic boom mitigation. The off-axis volume is supplied by a keel(s) below the forward portion of a supersonic vehicle. Linear theory predicts that two supersonic vehicles with the same cross sectional area distributions in planes inclined at the freestream Mach angle will asymptote to the same far field flow. The concept studied here increases the fineness ratio of a vehicle by adding volume under the vehicle, thereby increasing its apparent length. As such, the off-axis volume is designed to match the Mach plane area of a slender nose spike. The results presented here prove that off-axis volume addition can be very effective and efficient in increasing the apparent length of a vehicle and thereby greatly alleviating sonic boom. It is shown that a keel swept forward normal to the Mach plane can be effective and has a length efficiency factor equal to the freestream Mach number. It is further shown that heat addition can be substituted for off-axis volume. This heat addition can be generated as a by-product (the exhaust of) of a linear ramjet engine. The research described here uses a full range of models, including wind tunnel testing, to size, optimize and validate keels for sonic boom mitigation. 2001 by the American institute of Aeronautics and Astronautics, Inc. All rights reserved.
