Wave Rotor Design Procedure for Gas Turbine Enhancement

Abstract

This paper presents an analytical design procedure for pressure wave machines, also known as wave rotors, to enhance gas turbines and internal combustion (IC) engines in a topping or bottoming cycle. The advantage of using a wave rotor for improving the performance of gas turbines or internal combustion engines is that it uses a pressure and enthalpy exchange process. Employing pressure or even shockwaves for the energy transfer, no mechanical parts like pistons or blades are necessary inside the chamber (channel) that houses the process, which increases the air pressure delivered to the combustor of a gas turbine or cylinder of an internal combustion (IC) engine. The wave rotor has found fair success in its application to IC engines. Research and development continues for both, applications in IC engines and its originally envisioned application in gas turbines. Here an analytical 1-D algebraic wave model is realized by utilizing shockwave theory and linear gas dynamic principles to model the process in a 4-port wave rotor, with five wave reflections in the low pressure part for better gas scavenging. Using this analytical model, a comprehensive design space has been investigated and documented in performance maps. From this, conclusions and recommendations are drawn for performance and geometry optimization. The analytical algorithm has been validated using a 1-D commercial code GT-POWER and 2-D CFD code FLUENT. While here the interest is mainly in steady state operation, the analytical algorithm also models transient processes.