Quasi-steady flow model of slot-type casing treatments I: modeling method and validation

In order to predict more efficiently the compressor flow with slot-type casing treatment as well as to provide a computationally efficient tool for the design optimization of casing treatment, a quasi-steady flow model of the slot-type casing treatment flows was developed based on the understanding of the unsteady flow physics of the rotor-casing treatment combination. The new model has been coded up and validated against a slot-type casing treatment which was examined by experiment and unsteady RANS(Reynolds-averaged Navier-Stokes) calculations. Results show that the developed model predicts the extension of the rotor stall margin due to the application of the casing treatment quite well. Moreover, as compared to the unsteady simulation results, the model well reproduces the flow field in both the rotor passage and the casing treatment. The computational expenses using the flow model is just about 1% of that using unsteady simulations. This ensures that the model can be used to give fast prediction of the aerodynamic characteristics of a compressor with slot-type casing treatment, and the design and optimization of casing treatment are thus readily applicable.