Investigation on Influence of Design Parameters for Tandem Cascades Diffuser Using DOE Method

Abstract

The tandem cascade can be used as an efficient way to improve the compressor load. As for the interaction parameters between two rows of the tandem diffuser, it is known that the relative circumferential position, radial gap between two rows, ratio of chord length of two rows, difference of the stagger angle between the front row and rear row blades have significant impact on the performance of the tandem cascade diffuser. In the literature, there is a lack of references for evaluating quantitatively the influence of important tandem design parameters on the tandem diffuser, and thus the adjustment ranges of the tandem parameters cannot be determined accurately. In order to investigate the influences of the tandem design parameters on the compressor performance, in an economically affordable manner, the influences of the design parameters for the tandem cascades diffuser were investigated by Design of Experiments (DOE) method. The orthogonal experimental designs are performed for the radial gap R between the front row and rear row, inlet stagger angle θ of the rear row and relative circumferential position L between the front row and rear row of the tandem diffuser. The DOE analysis results demonstrate that the inlet stagger angle θ of the rear row has significant influence on the response value of total pressure ratio and isentropic efficiency. The relationship between the design parameters of the tandem diffuser and the compressor performance is obtained from the DOE method. The design parameters are adjusted and determined according to the DOE analysis, and then the validation calculations are carried out. The parameter selection capacity of DOE method has been validated by the results. The design parameters determined from DOE analysis can be effectively used in the design process of the tandem diffuser, with notably reduced amount of simulation of each parameter.