Influence of hydrogen-blended natural gas via pipeline transportation on aerodynamic performance of centrifugal compressor

In order to study the influence of hydrogen-blended natural gas via pipeline transportation on the aerodynamic performance and stable working range of centrifugal compressor, a three-dimensional geometric model was established based on the research object GE PCL503 compressor used in Sichuan-to-East Gas Pipeline. Meanwhile, 3D simulation was performed for the compressor with RANS method and comparison was carried out with the experimental data from literature to verify the accuracy of the numerical simulation model. The effects of different hydrogen blending ratios and inlet temperatures on the compressor's aerodynamic performance and surge margin were studied based on the 3D simulation model. The results show that the total pressure ratio and surge margin of the compressor decrease with the increasing of hydrogen blending ratio. Specifically, the surge margin and pressure ratio decrease by 19.78% and 6.44% respectively when the hydrogen blending ratio reaches 20%. Under the near-surge condition, the leakage vortex has its trajectory moved forward and its strength enhanced, which expand the low-speed area on the pressure surface and further accelerate the mixing of the leakage flow with the main flow and the secondary flow on the pressure surface. Thus, the flow separation on the pressure surface and the blockage of downstream channel are intensified. This is the main reason for reducing the stable working range of compressor after the increase of hydrogen blending ratio. When the inlet temperature increases from 288 K to 323 K at the hydrogen blending ratio of 10%, the total pressure ratio of the centrifugal compressor decreases by 4.27%, the isentropic efficiency decreases by 0.65%, the surge margin increases by 13.03%, and the energy flow decreases by 17.4% under the same volume flow. Generally, the research results could provide a theoretical basis for the design and safe operation of compressor for hydrogen-blended natural gas transportation.