Testing prototype of a multistage subsea pump to obtain the performance curves and vibration response. The performance will be evaluated in multiphase flow conditions. The current test rig is capable of testing 200 mm impellers with 250 HP power input at 3600 rpm. The pump performance will be evaluated for two fluids (water and air) covering the flow rate range and gas volume fractions (GVF) ranging from 0 to 60%. The pump speed will vary from 1500 to 3600 rpm with steps of 500 rpm. The performance measurements will include pump inlet pressure, pump outlet pressure, pump inlet temperature, pump outlet temperature, and rotor vibration from proxy probes mounted on the pump. All of the measurements indicated above will be performed for each of the operating condition conditions.