An inverse model for primary design parameter interaction of 1.5 stage counter-rotating turbine

One-and-a-half-stage counter-rotating turbines (CRTs) consist of one stator and two rotors; the blade rows rotate in opposite directions. The aerodynamic design process typically involves primary aerodynamic design, throughflow design, and three-dimensional geometry optimization. However, the process lacks an inversion model for propagating information in the opposite direction—from the throughflow design results back to the primary aerodynamic parameters, which is important for improving the accuracy of selecting the primary design parameters. This paper proposes a mathematical model based on Euler’s equation and the first law of thermodynamics, which establishes a connection between the primary design and throughflow design steps. This linkage enables reverse iteration from the throughflow design back to the primary aerodynamic design step to correct the primary design parameters, such as blade load coefficient, degree of reaction, and other input parameters of the throughflow design. The model was validated by using Reynolds-averaged Navier-Stokes (RANS) equations simulations with the Spalart-Allmaras (S-A) one-equation turbulence model, demonstrating a relative error ranging from 0.36% to 4.86%.