Abstract
In this paper, to study the effect of dynamic and static interference of clearance flow in fluid machinery caused by changes in rotational speed, the model was simplified to a rotor-stator system cavity flow. Investigating the flow characteristics in the cavity by changing the rotor speed of the rotor-stator system is of considerable significance. ANSYS-CFX was applied to numerically simulate the test model and the results were compared with the experimental results of the windage torque of the rotor-stator system. The inlet flow rate and geometric model remained unchanged. With an increase in the rotating Reynolds number, the shear stress on the rotor wall gradually increased, and the maximum gradient was within l* < 0.15. In addition to the shear stress, the tangential Reynolds stress Rrθ contributed partly to the torque on the rotor wall. The swirling vortex formed by entrainment in the cavity of the rotor-stator system tended to separate at ReΦ= 3.53 × 106. As the rotating Reynolds number continued to increase, the secondary vortex finally separated completely. The strength of the vortex in the rotor turbulent boundary layer decreased with an increase in the rotating speed, but the number of vortex cores increased with the increase of speed. Depending on the application of the fluid machine, controlling the rotating speed within a reasonable range can effectively improve the characteristics of the clearance flow.
Highlights
Combined withwith the charcharacteristics of the external characteristics, the internal flow was analyzed in a targeted acteristics of the external characteristics, the internal flow was analyzed in a targeted manmanner, reasons cause the changes in external the external characteristics ner, andand the the reasons andand lawslaws that that cause the changes in the characteristics were were summarized
The clearance inside a fluid machinery was simplified into a rotor-stator system cavity, and the experimental torque was compared with the numerical results
The rotor ReΦ was gradually increased from 2.12 × 106 to 4.23 × 106, and air with a constant inlet flow rate was selected to flow in from the axial direction and flow out freely in the circumferential direction of the cavity
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. By simplifying the clearance flow in fluid machinery into the cavity flow of a classical cylindrical inlet rotor-stator system, the internal flow was analyzed quantitatively by means of dimensionless parameters, and the variation law of disc torque at different rotating speeds was studied. Under the action of high-speed rotation and wall shear stress in the rotor-stator system, the clearance flow characteristics directly affect the aerodynamic performance and efficiency of the entire machine. This is of vital importance for the optimal design of fluid machinery with a clearance flow
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