Some Fluid Dynamic Research Techniques

Abstract

One of the main features characterizing gas-turbine technology has been the aerodynamic approach adopted towards such items as the axial compressor and turbine, the ducting components, and so forth. This has necessitated a lot of research into many basic fluid dynamic problems which had hitherto received little or no attention. Equipment has had to be constructed and special techniques developed or adapted to meet the new requirements. This lecture gives an account of such work, with particular reference to the methods adopted at the National Gas Turbine Establishment (N.G.T.E.). In the first part of the lecture the simple cascade tunnel has been described. Its design involves many features encountered in work of this nature, and touches on many basic principles. Following this, some special forms of cascade tunnel are described. For example, heat-transfer tunnels, an icing tunnel, and annular tunnels are considered as departures from the conventional. Following a few notes on ducting research, the final section deals with general instrumentation techniques. The measurement of air pressures and direction is considered, together with the measurement of gas and wall or blade-surface temperatures. Some mention is made of boundary layer investigation and high-speed flow visualization. An apparatus for determining the potential flow past blades is also described. All these have been selected as examples representing techniques which have contributed in some way to our knowledge, and hence to the development of the gas turbine.