CFD Simulation of a Centrifugal Compressor using Star-CCM+
Typ
Examensarbete för masterexamen
Program
Applied mechanics (MPAME), MSc
Publicerad
2022
Författare
Ravichandran, Sai Anirudh
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
With anthropogenic greenhouse gas every year, its effect on the climate change is
higher than ever and the need to curtail the emission of greenhouse gases is high.
Decarbonization of district heat pumps is a step in the right direction to reduce the
effects of such machines on climate change. In this case, the working fluid in the
heat pump is replaced from R134a which has a GWP of 1430 to R1234ze(E) which
has a GWP of 6.
The main aim of this work is to perform CFD simulations of a centrifugal compressor
using Star-CCM+. The compressor is tested for different outlet pressure conditions
to create a compressor map with in-depth analysis of the impact of various factors
on the performance. The working fluid is R1234ze(E) which is a low GWP refrig erant. The results obtained from the simulations would then be compared with the
in-house and ANSYS CFX results.
The process starts from acquiring the geometry and preparing it for meshing. The
main task was to add the inlet part and the diffuser part to the compressor. The
diffuser dimensions were provided which was added to the impeller. The final geom etry is then meshed appropriately and the physics models required are added. The
fluid and thermodynamic properties of the refrigerant are obtained from REFPROP
and are added to the material database. With all the prerequisites set, simulations
are performed. The outlet pressure is changed for every case and the important
compressor characteristics are noted.
Properties of the flow are recorded at different boundaries and are used to evaluate
the compressor performance using appropriate equations. The effect of different
turbulence models and real gas equations are studied. Also, the effect of the diffuser
on the compressor is studied by analysing the efficiency curve. The difference be tween the polytropic efficiency and the isentropic efficiency for a compressor is also
observed as expected. Finally, the operation analysis at design point and off-design
are performed by looking at the flow through the compressor at different spanwise
locations.
Beskrivning
Ämne/nyckelord
CFD, centrifugal compressor, isentropic efficiency, polytropic efficiency, pressure ratio.