A Velocity Triangle Analysis Method for Variable Geometry Turbines Based on One-Dimensional Isentropic Flow Theory

As a core component of next-generation variable cycle engines, variable geometry turbines (VGTs) face significant technical challenges in achieving high efficiency across a wide operating range. In turbine aerodynamic design, the selection of velocity triangle parameters at the design point critically impacts performance; however, traditional design methods of-ten struggle to optimize aerodynamic performance under off-design conditions. To address this issue, this paper proposes a velocity triangle analysis method for variable geometry turbines based on one-dimensional isentropic flow theory. This method innovatively analyzes three typical flow choking states under off-design conditions, enabling accurate prediction of velocity triangle parameters. Finally, the proposed method’s prediction accuracy is validated through comparisons with numerical simulation results. Further-more, this approach significantly reduces the design cycle of variable geometry turbines, providing a reliable theoretical tool for their rapid design.