Radial Forces Reconstruction on a Space Inducer From Casing Pressure Measurements

Axial inducers produce significant rotordynamic forces influenced by cavitation and flow rate. The decrease of the cavitation number increase the magnitude of the forces as does the decrease of the flow coefficient in experimental test rigs, these forces can be obtained by a balance mounted in the shaft. This can be expensive and can lead to some problems. This paper proposes a methodology to measure these forces using pressure signals at the casing for different axial and azimuthal locations, post processed by continuous wavelet transforms. The results obtained with this process are compared to reference signals coming from a six-components balance on the experimental water test-rig dedicated to the study of the performance and the unsteady phenomena in spatial inducer at the Fluid Mechanics Laboratory of Lille (LMFL). For the validation, different inducer geometries, flow rates and rotational speeds are used. Finally, an calibration is determined to evaluate the uncertainty of this methodology.