GB603155A - Improvements relating to gaseous fluid flow systems operating in supersonic velocity conditions - Google Patents

Abstract

603,155. Gaseous fluid flow systems operating under supersonic velocity conditions. POWER JETS (RESEARCH & DEVELOPMENT), Ltd., and SMITH, A. G. Feb. 1, 1945, No. 2611. [Class 4] [Also in Group XXXV] In a gaseous fluid flow system in which, when operating at the design point, velocity conditions obtain giving rise to a shock wave, means are provided for measuring the static pressure at two spaced points in the direction of flow, one on either side of the position at which the shock wave forms, and for controlling the conditions of operation of the system in accordance with the indication of the pressuremeasuring means to maintain a low and a high pressure upstream and downstream of the points respectively. Fig. 1 shows a supersonic wind tunnel with static pressure orifices A, B, C, of which B and C are located so as to include between them the zone in which the shock wave at the junction of the supersonic and subsonic sections form, and A is located well upstream of the zone, while Fig. 2 shows an aircraft wing with a variable-area air inlet 26 for operating under supersonic velocity conditions. The size of the air inlet is varied by pivoted flaps 27, and static pressure leads A, B, C are formed in a central casing 29. In each case, under normal conditions with the shock wave D located between B and C, the points A and B are at the same pressure, lower than that at C, but if conditions are such as to cause the shock wave to move upstream between A and B the pressure at A remains unaltered while the pressure at B rises to the value at C. The pressure orifices A, B, C may be connected to gauges, and the speed of the electric motor 3a or the jacks 28 controlling the flaps 27, controlled manually in accordance with the indications of the gauges. Fig. 3 shows an automatic control system in which the orifices communicate with pairs of capsules 5, 6 and 7, 8 respectively, which are interconnected by rigid links 9, 10 operating, through links 11, 12, switches 17, 22 which operate a device F for controlling the speed of the compressor motor 3a or the setting of the jacks 28. The circuits made by the switches 17, 22 are determined by the positions of the links 11, 12 in accordance with the pressures communicated to the capsules 5, 6, 7, 8.