On the role of back-propagating pressure suppression in enhancing the pressure-gain performance of quasi-2D rotating detonation engines

TL;DR

This study investigates how back-propagating pressure suppression affects pressure gain in quasi-2D rotating detonation engines, revealing the importance of flow channel optimization and check valve design for performance enhancement.

Contribution

It introduces an abstract check valve model and analyzes the impact of backflow suppression on pressure gain, providing theoretical guidance for RDE performance improvement.

Findings

Increasing back-propagating pressure suppression slightly improves PG.

Higher expansion ratios reduce back-propagating pressure but lower PG.

A large check valve strength is crucial for optimal flow channel design.

Abstract

The total pressure gain (PG) characteristics of the quasi-2D rotating detonation engine (RDE) are numerically investigated in this study, based on an abstract check valve model and the quasi-1D assumption. The influence of back-propagating pressure suppression on PG and its underlying mechanism are examined. An abstract check valve model is established to simulate various flow channel configurations, with backflow check strength $\alpha_b$ defined, where a larger $\alpha_b$ corresponds to a stronger backflow blocking effect. The quasi-1D assumption is applied along the axial direction to simplify the radial features of the annular RDE. The quasi-2D governing equations for RDE flow are derived. Simulations are conducted for varying expansion ratios $A_e$ and values of $\alpha_b$. The results indicate that increasing $\alpha_b$ effectively suppresses back-propagating pressure and slightly improves PG; however, it cannot fully eliminate the back-propagating pressure, as the check valve itself introduces flow disturbances. Increasing $A_e$ also suppresses back-propagating pressure but significantly reduces PG. Achieving positive PG requires reducing $A_e$ below a critical value. However, this reduction is limited by $\alpha_b$; further reduction in $A_e$ leads to forward propagation of back-propagating pressure to the engine inlet, resulting in inlet blocking. Therefore, a sufficiently large $\alpha_b$ is essential for the required reduction in $A_e$. The key aerodynamic challenge for achieving positive PG lies in optimizing flow channels to suppress back-propagating pressure efficiently. Finally, a general PG criterion is proposed by normalizing the quasi-2D RDE with stoichiometric hydrogen/air mixtures. This study provides theoretical guidance for enhancing PG in RDEs.