Wave Rotor Topping Cycles
for Gas Turbine Engines

Wave Divider Experiment

Wave Rotors, used as a gas turbine topping cycle, offer a potential route to higher specific power and lower specific fuel consumption. In order to exploit this potential properly, it is necessary to have some realistic means of calculating wave rotor performance, taking losses into account, so that wave rotors can be designed for good performance. This in turn requires a knowledge of the loss mechanisms. The divider experiment was designed to quantify the losses due to finite passage opening time, friction, and leakage. For simplicity, the experiment used a 3-port, or flow divider, wave cycle, but the results should be applicable to other cycles. In a divider cycle air enters the wave rotor through an inlet port at an intermediate pressure and exits through two separate ports. In one exit port the air is at a higher pressure than the inlet, while in the other port the pressure is lower. Thus, the device demonstrates the essential characteristics of unsteady work extraction and addition without the complication of an external combustor. A 12" diameter rotor was used in the NASA experiment, with two different lengths, 9" and 18", and two different passage widths, 0.25" and 0.54", in order to vary friction and opening time. To vary leakage, moveable end-walls were provided so that the rotor to end-wall gap could be adjusted.

The experiment has shown that there is an optimum passage width for any specific wave rotor application, since, as the passage width increases, friction losses decrease, but opening time losses increase, and vice-versa. Results also show that reduction of the rotor to end plate clearance gap leads to a large increase in performance.

Contact: Jack Wilson(QSS Group, Inc.)
email: Jack.Wilson@grc.nasa.gov

Project Contact: Daniel E. Paxson
Phone: (216) 433-8334
email: dpaxson@grc.nasa.gov

responsible official: sanjay garg
site maintenance: edmond wong
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last updated: 2.29.08