Some aspects of variable geometry gas turbine operation

Abstract

Many gas turbine thermodynamic cycles have been proposed which were designed to meet the propulsion requirements of future advanced aircraft. A thoughtful consideration of such designs is warranted as engines operating on such cycles will give a significant improvement in off-design performance. Such performance improvements can be brought about chiefly by the extensive use of variable geometry components. With the advent of the variable area turbine, a greater flexibility will be obtained in engine control and, hence, in aircraft operation. This paper examines the performance of a variable geometry engine that is suitable for V/STOL aircraft operation, and it discusses how certain aerodynamic and mechanical phenomena associated with variable area turbines may influence the design and limit the operation of future advanced gas turbines.