Abstract
The effects of single-arc blade profile length on the performance of a forward multiblade fan are investigated in this paper by computational fluid dynamics and experimental measurement. The present work emphasizes that the use of a properly reduced blade inlet angle (β1A) and properly improved blade outlet angle (β2A) is to increase the length blade profile, which suggests a good physical understanding of internal complex flow characteristics and the aerodynamic performance of the fan. Numerical results indicate that the gradient of the absolute velocity among the blades in model-L (reducing the blade inlet angle and improving blade outlet angle) is clearly lower than that of the baseline model and model-S (improving the blade inlet angle and reducing blade outlet angle), where a number of secondary flows arise on the exit surface of baseline model and model-S. However, no secondary flow occurs in model-L, and the flow loss at the exit surface of the volute (scroll-shaped flow patterns) for model-L is obviously lower than that of the baseline model at the design point. The comparison of the test results further shows that to improve the blade profile length is to increase the static pressure and the efficiency of the static pressure, since the improved static pressure of the model-L rises as much as 22.5 Pa and 26.2%, and the improved static pressure efficiency of the model-L rises as much as 5 % at the design flow rates. It is further indicated that increasing the blade working area provides significant physical insight into increasing the static pressure, total pressure, the efficiency of the static pressure and the total pressure efficiency.
Highlights
It is well known that centrifugal fans have been widely adopted to industrial application, such as cooling units in air-conditioning, heating, ventilating and air conditioning systems, and home appliance machines [1,2,3,4,5]
Finite element methods [24,25,26,27] and the finite volume method [28,29] are very effective tools to Finite element methods [24,25,26,27] and the finite volume method [28,29] are very effective tools to solve some partial differential equations (PDEs) on complex geometries, which is applied in a wide solve some partial differential equations (PDEs) on complex geometries, which is applied in a wide range of engineering and biomedical disciplines [30,31,32,33,34]
Our work suggests that reducing the blade inlet angle (β1A > 60◦ ) and improving the blade outlet angle (β2A < 175◦ ) can provide a significant increase on the static pressure and the efficiency of static pressure, which improves the aerodynamic load of the forward multiblade fan to achieve the aim of energy conservation
Summary
It is well known that centrifugal fans have been widely adopted to industrial application, such as cooling units in air-conditioning, heating, ventilating and air conditioning systems, and home appliance machines [1,2,3,4,5]. Complex turbulent structures due to rotating Coriolis force and narrow blade passage in the internal flow of a forward multiblade fan play a dominant role in directly affecting the performance of the fan. Our work indicates that by reducing the blade inlet angle (β1A , β1A > 60◦ ), improving the blade outlet angle (β2A , β2A < 175◦ ) and increasing the blade’s working area may provide significant physical insight into increasing the static pressure and the efficiency of this static pressure. It gives insight into improving the aerodynamic load of fans to achieve the purpose of energy conservation.
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