One-dimensional modeling for tip clearance leakage vortex trajectory and stall-onset prediction in subsonic centrifugal impellers

Abstract

Two one-dimensional models are established for the tip leakage vortex trajectory and rotating stall-onset point prediction respectively for subsonic centrifugal impellers. The goal of modeling is to supply an effective estimation strategy of the stall-onset point for use in the one-dimensional performance prediction stage. The tip leakage vortex trajectory prediction is a critical part of the stall-onset prediction. The proposed one-dimensional model (one-dimensional tip leakage vortex trajectory model) to predict the tip leakage vortex trajectory is based on blade loading, i.e. the velocity difference between the pressure and suction surfaces. The loading function considers the effect of radial rotation, blade turning, and passage width variation. Compared with the computational fluid dynamics results, the current model shows reasonable accuracy, with an average relative error below 12.35%. The one-dimensional prediction model (Model II) is developed to determine the stall-onset point, where the interface between the tip leakage flow and the main flow spills from the blade leading edge. In this model, the momentum balance analysis is applied to identify the position of the interface. The parameter of the tip leakage vortex trajectory in Model II is determined by one-dimensional tip leakage vortex trajectory model. The effective origin of the tip leakage flow is correlated with the rotational speed and tip clearance. The effectiveness of Model II is validated with the experimental and computational fluid dynamics results using three impellers. Compared with the conventional model (Model I), Model II shows better accuracy, with a maximum error of about 7.42%.

Numerical Investigations on Slip Characteristics and Slip Onset Position in High-Loaded Backswept Centrifugal Impellers

“…This case had been computed in author's pervious papar (Zhang et al, 2019), so we will not describe in detail in this paper. The flow condition at the inlet and outlet and the computation method were same as the pervious paper, which can be referenced (Zhang et al, 2019). Therefore, the results of validation were also same as the pervious paper (Zhang et al, 2019).…”

“…The flow condition at the inlet and outlet and the computation method were same as the pervious paper, which can be referenced (Zhang et al, 2019). Therefore, the results of validation were also same as the pervious paper (Zhang et al, 2019). As shown in Figure 4 and Figure 5, the agreement between CFD and experiments was not good, especially near the choke, due to the deviation of the properties of air, simulation model and turbulence model.…”

Theoretical Analysis of Isentropic Exponent Effects on the Internal Flow of Supercritical CO2 Centrifugal Compressors

“…e relative velocity difference between the two sides of an impeller blade approximately satisfies the following equation under a small attack angle condition [40]. It can be seen from the above formula that the blade loading is composed of three parts and the presented research shows that the contribution of the third term to the blade load is tiny and thus can be ignored [41]. erefore, it can be simplified as follows:…”

Phase Distribution in the Tip Clearance of a Multiphase Pump at Multiple Operating Points and Its Effect on the Pressure Fluctuation Intensity

“…In the meantime, the rotor and stator interaction (RSI) was the reason for the pressure fluctuation, and the TLF had less effect on the impeller inlet and middle region within a certain range. In addition, some other scholars applied numerical simulation methods to investigate the TLF in turbomachinery such as centrifugal pumps [27,28], compressors [29,30], fans [31,32].…”