Design And Optimation For Cross Flow Fan In Air-conditioning

With the advances of standards for living, people have raised a higher requirement for the household electrical appliance. It is also reflected on the requirements for the air condition: the flow rate of the cross flow fan should be higher and the noise of the fan should be lower. The structure of the fan is simple and its volume is small, the flow it blow out is straight and well-distributed , what is more, the flow can move a long distance because of its high specific pressure ratio. The similarity method which is commonly used in the field of fan design can not be used in the design of the cross flow fan because of the existence of the eccentric vortex inside the fan, the fact has lead to such a result: the design of the fan mainly depends on the experimental data, and the cost is expensive. In this paper, a cross-flow fan model has been developed, and the inner flow field of the cross flow fan has been simulated by a commercial CFD software, and the aero-acoustic noise is forecasted by the Ffows Williams-Hawkings equations. This method has been proved efficient. Some character parameters of the cross flow fan have been researched with the criterion of flow rate and the noise by the method above in order to find the help us achieve the optimum design. The works contain aspects below:Firstly, a new model of cross flow fan has been developed with relative method and some empirical data. The inner flow field has been simulated by FLUENT. The results of the numerical simulations show the existence of the eccentric vortex which controls the whole flow field in the model. What is more, in the paper, the performance curve has been sketched and the results of the model have been analyzed.Secondly, we have done some optimization to different blade length, blade number, and different blade line with the current model in order to find the varying rules for them under the same static pressure and rotational speed conditions. It is very useful to provide some guidelines to us for designing the model.In this paper, we have found that the flow rate for the cross flow fan will increase when we add the number of blades, and it has limited influences to the noise of the fan. For a certain cross flow fan ,it has an optimal number of blades. Within the range discussed in this paper, in order to have a higher flow rate and a lower noise, it is better to have a thicker blade. The double circular can increase the flow rate and decrease the noise of the fan, but it needs to be well designed in order to achieve such purpose.