A supersonic tunnel design for testing engine intakes

Abstract

The object of this investigation was the design of a supersonic wind tunnel for use in determining the internal flow in engine intakes between Mach 1.5 and Mach 3 and in ranges of pitch (+ 15 deg) and engine mass flow experienced in flight. It was shown that from a theoretical standpoint an open jet tunnel was the most effective for this particular purpose provided that its aerodynamic efficiency was comparable with that of any alternative type. Little data on this last point was available so that experimental work was required to confirm the above choice. As preliminary tests showed that an efficient open jet tunnel was indeed possible, the experimental work was continued and an effective tunnel arrangement consisting of a simple variable Mach number effuser and variable geometry diffuser was developed. This development work originally concerned the design of a practicable high-speed cell for an Engine Test Facility I and only later, using data accumulated in this investigation, a 6 in. x 6 in. tunnel capable of testing a 4 in. diameter inlet was constructed. A brief description of this tunnel is given.