Atividade

An implicit, time-accurate 3D Reynolds-averaged Navier-Stokes (RANS) solver is used to simulate the rotating stall phenomenon in a plastic centrifugal fan. The goal of the present work is to shed light on the flow field and particularly the aerodynamic noise at different stall conditions. Aerodynamic characteristics, frequency domain characteristics, and the contours of sound power level under two different stall conditions are discussed in this paper. The results show that, with the decrease of valve opening, the amplitude of full pressure and flow fluctuations tends to be larger and the stall frequency remains the same. The flow field analysis indicates that the area occupied by stall cells expands with the decrease of flow rate. The noise calculation based on the simulation underlines the role of vortex noise after the occurrence of rotating stall, showing that the high noise area rotates along with the stall cell in the circumferential direction.

As the power source of the air and gas system in the thermal power plant, the operation status of the centrifugal fan is directly related to the safe and economic operation of the power plant. Rotating stall in the centrifugal fan is a local instabilities phenomenon in which one or more cells propagate along the blade row in the circumferential direction. The nonuniform flow, the so-called stall cell, rotates as a fraction of the shaft speed, typically between 20% and 70%. This running mode is responsible for strong vibrations which could damage the blades . Meanwhile, it will increase the aerodynamic noise.