Investigation on Unsteady Flow Characteristics of a SCO2 Centrifugal Compressor

Abstract

Supercritical carbon dioxide (SCO 2 ) is a vital working fluid in the application of power units and its high density helps to achieve a compact mechanical structure. Centrifugal compressors are of vital use in various kinds of equipment. In this paper, a SCO 2 centrifugal compressor of large input power and mass flow rate is designed and numerically investigated. A thorough numerical analysis of the unsteady flow field in the centrifugal compressor is performed in ANSYS-CFX. The computation adopts hexahedral mesh, finite volume method, and the RNG k-ε two-equation turbulence model. Streamlines, temperature, pressure, and Mach number distributions at different time steps in one revolution period are covered to present the unsteady effect of turbomachinery. Meanwhile, the force on a single rotor blade is monitored to investigate the frequency components of exciting force, thus providing the foundation for vibration analysis. Moreover, the torque, output power, pressure ratio, and isentropic efficiency in the steady and the unsteady time-averaged condition are calculated and compared with the design condition to measure the validity of the design. In summary, the unsteady computation result reveals that the unsteady flow characteristics are prominent in the designed compressor and the design of impeller and diffuser meet the requirement.

Experimental and CFD Simulation Studies on Bell-Type Air Nozzles of CFB Boilers

“…Therefore, the RNG k-ε was used for calculation. The model was developed by Yokhot and Orszag et al [27,28] using the RNG method based on the standard k-ε model, which is suitable for the simulation of high-speed gas flow [7,14,[29][30][31].…”

Loss Mechanism of Static Interstage Components of Multistage Centrifugal Compressors for Integrated Blade Design

“…Centrifugal compressors are a class of machinery universally used in industry [1] that have a wide range of applications and consume a large amount of energy. The demands of industry, resulting from the need to sustain and accelerate economic growth, have meant that multistage centrifugal compressors are widely used.…”

Preliminary Design and Model Assessment of a Supercritical CO2 Compressor

“…However, when the inlet condition was approaching the critical point, their deviation became more and more obvious. Yuqi Wang et al (2017) carried out steady and unsteady numerical simulations of a SCO 2 centrifugal compressor with ANSYS-CFX [19], which showed that the difference between the two results is small. But, it should be pointed out that the equation of state used in their calculation is not accurate enough for SCO 2 .…”