This paper considers the effect of excessive total pressure losses for heat transfer problems in fluid flows with a high circumferential swirl component. At RWTH Aachen University, a novel gas generator concept is under research. This design avoids some disadvantages of small gas turbines and uses a rotating combustion chamber. During the predesign of the rotating combustion chamber using computational fluid dynamics (CFD) tools, unexpected high total pressure losses were detected. To analyze this unknown phenomenon, a gas–dynamic model of the rotating combustion chamber has been developed to explain the unexpected high Rayleigh pressure losses. The derivation of the gas–dynamic model, the physical phenomenon related to the high total pressure losses in high-swirl combustion, the influencing factors, as well as thermodynamic interpretation of the Rayleigh pressure losses, are presented in this paper. In addition, the CFD results are validated by the gas–dynamic model derived. The results presented here are of possible interest for a wide range of applications, since these fundamental findings can be transferred to all heat transfer problems in fluid flows with a high circumferential swirl component.