Average and Instantaneous Heat Release to the Walls of an RDE

Abstract

Experimental results are shown for the net equilibrium heat release into containing walls of a 6-inch water-cooled Rotating Detonation Engine (RDE). Typical RDE operating regimes require active cooling techniques to dissipate the immense heat released by the rotating detonation waves and following deflagration waves. The water-cooled RDE in this study was run to thermal equilibrium at several equivalence ratios and mass flow rates. The heat release into each wall is presented as a function of equivalence ratio and mass flow rate. The general trend shown by data collected is that average heat absorption is greater during steady detonation modes than during other combustion events in the channel. This manifested as a 20% total heat loss to the walls during steady detonation, and less than 15% total heat loss for other modes. Equivalence ratio had a much weaker effect on heat absorption by the cooled walls as a percentage of mixture heat of combustion. In addition, a two-sided Resistance Temperature Detector (RTD) array over Kapton tape was used to measure heat flux into the wall of an RDE at 1 MHz for short-duration runs. At .25 inches axially into the detonation channel, the heat flux gage reached stable thermal equilibrium around 250°C, and derived heat pulses matched the frequency seen by high-speed video as well as pressure waves in the detonation channel. Between the long runs to thermal equilibrium and the short runs with higher fidelity, this research provides a great deal of information about the heat release in an RDE.