Authors: Nicolas Buffaz Isabelle Trébinjac
Publish Date: 2012/01/12
Volume: 21, Issue: 1, Pages: 1-12
Abstract
Numerical and experimental investigations were conducted in a transonic centrifugal compressor stage composed of a backswept splittered unshrouded impeller and a vaned diffuser A detailed analysis of the flow in the inducer ie the entry zone of the impeller between the main blade leading edge and the splitter blade leading edge is proposed from choke to surge Steady and unsteady simulations were performed using the code elsA which uses a multidomain approach on structured meshes and solves the compressible RANS equations associated with a twoequation turbulence model kl in the rotating frame of reference The 1MW LMFAECL test rig was used for carrying out the tests in the compressor stage Unsteady pressure measurements up to 150 kHz and Laser Doppler Anemometry measurements were performed in the inducer A good agreement is obtained between the experimental and numerical data even if an over dissipation is noticed in the numerical results The change in flow pattern from choke to surge is mainly due to a change in the tip leakage flow trajectory which straightens leading to a flow blockage of an individual passage near shroud A spectral analysis shows that only the blade passing frequency and its harmonics compose the various spectra obtained from choke to surge
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