QUANTIFYING HEAT TRANSFER EFFECTS OF A HIGH-SPEED, MULTI-STAGE, AXIAL RESEARCH COMPRESSOR
thesisposted on 2021-11-22, 14:00 authored by Nicholas Kormanik IIINicholas Kormanik III
A common assumption often made of dynamic compressors is that they are considered adiabatic, due to the fast-moving flow passing through the turbomachine and the small amount of any heat transfer relative to the large amount of work transferred to/from the flow. This research investigation combined the use of experimental measurements and computational simulations to take a deeper look into the implications that arise from applying this adiabatic assumption or neglecting heat transfer within a high-speed, multi-stage, axial compressor.
Preliminary testing of the Purdue 3-Stage (P3S) Axial Compressor Research Facility indicated the presence of heat transfer through stagnation temperature rises across stationary blade rows and higher than expected temperatures on the outside of the aluminum compressor casing, particularly in the front stages. Further experiments performed on the PAX200 compressor in the P3S facility involved a combination of surface temperatures, heat fluxes, and flow stagnation temperatures within the shrouded stator cavities and flowpath. These measurements confirmed that heat transfer was present throughout the stationary components (stators and casing) of the compressor and showed that they could noticeably affect the thermal flow properties within the compressor.
The influence of the heat transfer through these components was further explored through computational simulations, which showed the importance of incorporating conjugate heat transfer into the model and applying the correct thermal boundary conditions on the outside of the casing. Additionally, the effects on the spanwise temperature of the flow through increased spanwise mixing, convection, and different geometric and material properties of the casing were also explored. Overall, this investigation seeks to establish a correct thermal boundary condition and approach for validation of computational model. It also aims to reconcile the differences between computational models and experimental data by quantifying the impact that heat transfer has on isentropic efficiency for diabatic compressors.