The Flow of Gases at Sonic and Supersonic Speeds

Abstract

Problems involving the flow of gases at velocities near to or exceeding that of sound have been familiar to mechanical engineers for many years in connexion with the design of steam nozzles, and much valuable information has been accumulated from experience and from specific researches such as the classical work of Stodola (1927)‡ and of the Steam Nozzles Research Committee of the Institution (1923, etc.). The flow of steam through a converging-diverging nozzle, however, is only one instance of the flow of a gas in circumstances in which changes in density and pressure are produced or accompanied by changes in velocity. Behaviour of this kind is frequently referred to as compressible flow and arises in the design of gas turbines, in the jet propulsion of aircraft, in some high speed compressors, in diffusers, in flow through valves and measuring nozzles, in high speed aircraft and in the flight of projectiles.

The subject of compressible flow is thus of great importance in a wide range of problems of practical engineering and as it has not yet reached a stage at which the essential features are treated in textbooks readily available to engineers, the present paper has been written to cover as wide a field as practicable. The authors' main experience of the subject has been in the field of external ballistics and in the design, development, and use of supersonic wind tunnels; and the illustrations are taken largely from such work. The principles are of universal application, and it is hoped that the discussion will be on general lines and range over a wide field of applications from various branches of engineering practice.