A wave rotor, which acts as a high-technology topping spool in
gas turbine engines, can increase the effective pressure ratio
as well as the turbine inlet temperature in such engines. The
wave rotor topping, in other words, may significantly enhance
engine performance by increasing shaft horse power while reducing
specific fuel consumption. This performance enhancement requires
optimum selection of the wave rotor's adjustable parameters for
speed, surge margin, and temperature constraints specified on
different engine components. To examine the benefit of the wave
rotor concept in engine design, researchers soft coupled NASA
Lewis Research Center's multidisciplinary optimization tool COMETBOARDS
and the NASA Engine Performance Program (NEPP) analyzer.
The COMETBOARDS-NEPP combined design tool has been successfully used to optimize wave-rotor-topped engines. For illustration, the design of a subsonic gas turbine wave-rotor-enhanced engine with four ports for 47 mission points (which are specified by Mach number, altitude, and power-setting combinations) is considered. The engine performance analysis, constraints, and objective formulations were carried out through NEPP, and COMETBOARDS was used for the design optimization. So that the benefits that accrue from wave rotor enhancement could be examined, most baseline variables and constraints were declared to be passive, whereas important parameters directly associated with the wave rotor were considered to be active for the design optimization. The engine thrust was considered as the merit function. The wave rotor engine design, which became a sequence of 47 optimization subproblems, was solved successfully by using a cascade strategy available in COMETBOARDS. The graph depicts the optimum COMETBOARDS solutions for the 47 mission points, which were normalized with respect to standard results. As shown, the combined tool produced higher thrust for all mission points than did the other solution, with maximum benefits around mission points 11, 25, and 31. Such improvements can become critical, especially when engines are sized for these specific mission points.
Previous articleLast updated April 30, 1997
Responsible NASA Official:
Gynelle.C.Steele@nasa.gov
216-433-8258
Point of contact for NASA Glenn's Research & Technology reports:
Cynthia.L.Dreibelbis@nasa.gov
216-433-2912
SGT, Inc.
Web page curator:
Nancy.L.Obryan@nasa.gov
216-433-5793
Wyle Information Systems, LLC
