Instability Problem of Turbo-Machines with Radial Distortion Problems

Authors: Yasuo Obikane, Sofiane Khelladi

Abstract:

In the upstream we place a piece of ring and rotate it with 83Hz, 166Hz, 333Hz,and 666H to find the effect of the periodic distortion.In the experiment this type of the perturbation will not allow since the mechanical failure of any parts of the equipment in the upstream will destroy the blade system. This type of study will be only possible by CFD. We use two pumps NS32 (ENSAM) and three blades pump (Tamagawa Univ). The benchmark computations were performed without perturbation parts, and confirm the computational results well agreement in head-flow rate. We obtained the pressure fluctuation growth rate that is representing the global instability of the turbo-system. The fluctuating torque components were 0.01Nm(5000rpm), 0.1Nm(10000rmp), 0.04Nm(20000rmp), 0.15Nm( 40000rmp) respectively. Only for 10000rpm(166Hz) the output toque was random, and it implies that it creates unsteady flow by separations on the blades, and will reduce the pressure loss significantly

Keywords: inlet distorsion, perturbation, turbo-machine

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1078691

References:

[1] CAMPOS-AMEZCUA R., KHELLADI S., BAKIR F., CZERWIEC Z.M., SARRAF C., REY R., "Numerical Analysis of Unsteady Cavitating Flow in an Axial Inducer", Part A: J. Power and Energy, 2010, 224 (2), 223-238.
[2]KHELLADI S., KOUIDRI S., BAKIR F., REY R.
[2] "Flow Study in the Impeller-Diffuser Interface of a Vaned Centrifugal Fan", ASME Journal of Fluids Engineering, 127 , pp. 495, 502 - 2005
[3] Obikane Y., Kaneko M., Kakioka M, Ogura K."Image Analysis of Fine Structures of Supercavitation in the Symmetric Wake of a Cylinder", WASET, proceedings, Paris, June 24, 2011