Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 07, 2019 - November 08, 2019
In this study, numerical calculations were performed using blade models with different thicknesses in order to reduce the noise caused by the separated/reattachment flow between the blades of a sirocco fan used in a blower of a car air conditioner. The blade model is a fixed model that reproduced three sirocco fan blades. Reynolds number of the flow into the blade was fixed at the maximum of the actual machine, and the flow field and pressure field were visualized to clarify the relationship between the blade thickness and the flow field. As the blade thickness increased, the following three points have been found. (1)The separation position changes, (2)The blade surface fluctuation pressure becomes large when separation occurs at the blade surface compared to the leading edge separation, (3)The variation in force applied to the blade surface decreases. Furthermore, the noise generated from the blade surface was estimated using Curl's theory assuming that the blade surface is smaller than the wavelength of the sound wave, and the relationship between the blade thickness and the generated noise was examined. It was found that as the blade thickness increases the fluctuation of the force applied to the blade surface decreases, From this result, the noise generated by the interference with the blade surface is expected to decrease.
