The potential thermodynamic gain of rotating detonation combustors (RDCs) is typically represented as a pressure gain or increase in total pressure. However, defining a singular total pressure for pressure gain requires averaging due to the unsteady and nonuniform flow. The choice in averaging is nontrivial, and this work details the procedures that conserve the flow’s entropy, thrust output, and work output. These, along with area averaging, are compared to the accepted equivalent available pressure (EAP), with a key finding being that the experimental EAP is equivalent to area averaging. Sample results from three-dimensional direct numerical simulations were analyzed for demonstrative purposes. The experimental EAP was found always to be conservative and underpredicts the other averages by 2.5–38%, with entropy averaging being the most idealistic. This analysis highlights that work averaging is not equivalent to thrust averaging, as the work-averaged total pressures were 4–8% larger. The nonuniqueness in total pressure is exacerbated by the thrust averaging being sensitive to the assumed ambient exit conditions, unlike the work averaging. Overall, this paper highlights that the appropriate averaging procedure depends on the desired RDC application, as the outlet total pressure, needed to define pressure gain, is not intrinsic to the flow after a reduction in dimensionality.
Averaging the Nonuniform Flow in Rotating Detonation Combustors to Determine Gain
AIAA Journal ; 63 , 8 ; 3048-3063
2025-08-01
Article (Journal)
Electronic Resource
English