Development of an Experimental Facility to Characterize Performance, Surge, and Acoustics in Turbochargers

A cold turbocharger test facility was designed and developed at The Ohio State University to measure the performance characteristics under steady state operating conditions, investigate unsteady surge, and acquire acoustic data. A specific turbocharger is used for a thermodynamic analysis to determine the capabilities and limitations of the facility, as well as for the design and construction of the screw compressor, flow control, oil, and compression systems. Two different compression system geometries were incorporated. One system allows compressor performance measurements left of the surge line, while the other incorporates a variable-volume plenum. At the full plenum volume and a specific impeller tip speed, the temporal variation of the compressor inlet and outlet and the plenum pressures as well as the turbocharger speed is presented for stable, mild surge, and deep surge operating points. The behavior at these operating points is also analyzed in the frequency domain to examine particularly the discrete low frequencies and amplitudes associated with the surge oscillations. Finally, mild and deep surge frequencies are compared with calculated Helmholtz frequencies as a function of impeller tip speed and plenum volume.