Numerical Simulation And Experiment Research Of The Air Condition Axial Fans Matching The Shroud

With the development of social economy and rigorous demands of energy and environment, the performance demands to axial flow fan of these fields are higher. Propeller fans with a shroud covering only the rear region of their rotor tips are widely used as cooling fans installed in the outdoor unit of split room air conditions and in the engine block of automobiles. In addition to compactness, the need for low noise and high efficiency in these systems is rapidly increasing. The skewed-swept blade at its leading edge has been used in the power fans and air-conditioning fans in order to get higher performance and lower noise. But its mechanism about reducing loss and enhancing efficiency hasn't been clear until now. So it has important significance to predict the internal flow structure of axial flow fan using a mature commercial CFD software. In this thesis, numerical simulation using fluent software based on Navier-Stokes equations coupled with K-εturbulence model has been used to study the internal flow of axial flow fan. For the case of the open axial flow fan used in air-conditioners, numerical simulation is used to analysis the internal flow phenomena such as tip vortex inside this fan. These flow features can be used for understanding the flow mechanism of its fan and foundation of improving its flow structure and reducing noise. A really cooling fans system has been simulated and the internal flow has gained. The vortical flow field near the rotor tip in propeller fans has been discussed while the stated pressure changing. According to these study, the flux and noise characters of the two new designed balde have been tested. The relation between the vortical flow field and the noise in propeller has been discussed. The shroud affects the performance of axial flow fan greatly. So this thesis also analyze the internal flow structure of this fan with two types of shroud for reducing the noise level. According to the calculation, the influence to the flux character of the models with different simplification is small. But exact model is needed to gain the accurate internal flow. According to the theory of the noise, the structure of the axial flow fan system is adjusted to reducing the noise level.