An investigation of energy addition to a compressible gas via the hydraulic analogy

Abstract

The hydraulic analogy to the isentropic flow of a compressible fluid has long "been recognized." This study was undertaken to find some means, if possible, of extending the analogy so as to simulate the addition of heat in compressible fluid flow. It was shown that while the analogy does not hold for this phenomenon or for any non-isentropic process, a method does exist by which the isentropic addition of energy may be simulated. A secondary aim of the investigation was to study and improve the performance of the laboratory water table of the Department of Aeronautics, United States Naval Postgraduate School. The objective was to make the equipment suitable both for flow visualization demonstrations and for further research purposes. The water table was rebuilt to include a lighted surface incorporating a two-inch grid for photographic reference. An accurate method of measuring local and reservoir water depths was established. Photographs were taken of flow about models of various shapes to demonstrate the usefulness of the water table and the hydraulic analogy in the study of such flows.