Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade

Abstract

In this study, some of the optimal parameters for a new-style marine axial flow fan are defined by using numerical simulation and experimental tests with a large marine axial flow fan, based on the analysis of the blade perforation’s influences on its internal flow field and aerodynamic noise characteristics. Test result shows that the noise reduction for the axial flow fan with perforated blade is about 3 dB when the blade perforation diameter D is 10 mm and its deflection angle α is 45°. The results of the study show that there is an inhibitory effect on the discrete noise of axial flow fan with perforated blade on the tip area, and its total noise level emerged as the fluctuated distribution characteristics with the increase in the perforation diameter D and reduced along with the increase in the deflection of perforation angle α, at the same time varied as a linear characteristics, which can be reasonably explained by the acoustic interference theory. The results of the study have also further confirmed that the improvement of the flow of axial flow fan with perforated blade helps to reduce the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer, thereby suppressing the back-flow and vortex from the pressure surface to the suction surface efficiently. It is indicated that the improved vortex shedding phenomenon at the blade trailing edge after perforation on the area of blade tip is the main reason for the aerodynamic noise reduction of axial flow fan.

Pressure fluctuation–vortex interaction in an ultra-low specific-speed centrifugal pump

“…The monitoring of complex inner flow phenomena in the hydraulic machinery has been a hot topic. 5,6 The detection and diagnosis of the inception and the severity of cavitation provide means for preventing accidents. When severe cavitation occurs, it is usually accompanied by significant noise.…”

Patterns in change and balancing of aerodynamic imbalance of the low­pressure axial fan impeller

“…If there is only one impeller and there is no a directing vane, the aerodynamic imbalance and noise of the fan are determined mainly by the aerodynamic characteristics of blades. Papers [9][10][11][12][13] investigated and optimized separate blades. Authors of [9] studied the impact of through openings in a blade on the noise of the fan.…”

“…Axial fans are widely used in industry and in everyday life [1][2]. Reduction of noise and vibration during operation of axial fans is a relevant scientific and technical task [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Ordinary and aerodynamic (gas-dynamic) imbalances of the fan impellers are the main source of vibrations in fan machines [3][4][5][6][7][8].…”

“…Ordinary and aerodynamic (gas-dynamic) imbalances of the fan impellers are the main source of vibrations in fan machines [3][4][5][6][7][8]. The noise and vibrations of fans are also influenced by the geometry of blades [9][10][11][12][13].…”

Volume Flow Rate Optimization of an Axial Fan by Artificial Neural Network and Genetic Algorithm

“…Their results indicated that the convex grooves on the blade pressure surface changed the turbulent structures near the wall, and the wave-shaped trailing edge changed the flow direction of vortex shedding, which would reduce the influence of vortex shedding on the far-field region. Yang et al [7] analyzed the influence of the blade perforation on the internal flow field and aerodynamic noise characteristics. The results showed that the perforated blades improved the flow in the axial fan and reduced the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer.…”