Аналіз методів визначення куту відхилення для плоских решіток турбін

This paper presents a review of methods for predicting the flow exit angle from a planar turbine cascade operating with subsonic and transonic flow regimes. An analysis of empirical correlations used to determine the deviation angle is performed, and the advantages and limitations of each approach are discussed. The accuracy of empirical correlations and the CFD approach is evaluated by comparing their predictions with experimental data obtained for the VKI turbine cascade profile under both design and off-design operating conditions. The comparison reveals a low prediction accuracy of empirical correlations for considered regimes. The largest discrepancies are observed at outlet Mach numbers below 0.6. The closest agreement with experimental data is achieved using CFD (AxCFD™). The results show good consistency both in terms of the absolute values of the deviation angle and the trend of its variation under off-design conditions. Additional CFD simulations of three planar turbine cascade configurations demonstrate a significant influence of blade geometry on the predicted deviation angle. The relationship between the kinetic energy loss coefficient and the deviation angle is also discussed. Both CFD and experimental results indicate that the minimum loss condition corresponds to the minimum deviation angle. Furthermore, a consistent trend in the variation of these two parameters is observed across different operating regimes. It is concluded that accurate prediction of the deviation angle is a complex problem requiring consideration of a wide range of geometric and operating parameters of the cascade. Further research in this area is recommended.