Measured Heat Transfer in a Transonic Fan Rig at Casing With Implications on Performance

A highly loaded transonic fan with a splittered rotor and maximum pressure ratio of 2 has been tested at the Naval Post-graduate School. Temperatures on the casing outer wall have been measured using thermocouples in order to assess the heat transfer. An axisymmetric heat transfer analysis has shown that the heat transfer downstream of the rotor through the casing leads to an overstatement of the experimental efficiency by 0.36% and 0.29% for 100% and 90% speed respectively. Just above the rotor is an abradable material that can be considered adiabatic. Thus heat escapes only aft of the rotor and upstream of the total pressure and total temperature probes. For rotors without an adiabatic casing, the effect would be considerably higher. This has a large effect on the exit total temperature profiles which are often not matched well with CFD using an adiabatic boundary condition. In addition, heat transfer coefficients have been determined that can be used to assess other compressor applications.