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In this paper, we present our results on a relatively new kind of blower called Volumetric Resistance Blower (VRB) for cooling of portable computing platforms like laptop computers. The VRB performance was modeled numerically and compared to traditional bladed blowers. The sources of noise, dominant in bladed blower, are absent in case of VRB, because it uses a continuous porous disk instead of discrete blades. Thus, even though at iso-rpm, VRB yielded lower flowrate, its iso-acoustic performance could be superior. Hence, further analysis was crucial to quantify the potential benefit. The acoustics experiments for bladed blower and VRB were conducted in a hemi-anechoic chamber in accordance with ECMA-74 and ECMA TR/99 standards. Iso-acoustics pressure versus volume flowrate plot for both bladed blower and VRB are compared. VRB was found to have superior performance as compared to bladed blower. The volume flowrate at open flow condition for bladed blower and VRB are comparable, but as back pressure increased the flowrate yielded by VRB kept increasing and at stagnation condition, VRB showed around 79% higher static pressure. In the second part of the work, the experimentally validated numerical model for VRB was used for numerical optimization using a design of experiments (DOE) approach and varying the geometrical parameters. Rotor distance (minimum distance from the axis of rotation of impeller to the cutwater surface) was found to be the most important parameter, and an optimum value was found. A second DOE elucidated the optimal rotor hub center location in the two-dimensional space inside the casing as when the rotor is tucked back into the casing as much as possible and when the rotor distance is above 20.15 mm. A partial P–Q curve is generated (up to 20 Pa) for optimal geometry configuration. Based on the numerical and experimental evidence, VRB is found to have the potential to replace traditional bladed design in portable computing devices. In addition, due to absence of blades, it creates lower tonal noise, giving a much more comfortable experience to the end user.

This paper presents an experimentally validated modeling methodology for a new type of blower design known as volumetric resistance blower (VRB). It replaces the traditional centrifugal blower fan blades with a continuous porous medium disk and has been reported to be capable of providing a lower acoustic noise for the same output flow compared to a traditional blower. A three-dimensional transient numerical model of VRB is developed which incorporates the movement of a porous rotor using experimentally determined foam parameters to characterize the porous drag effect and a sliding mesh to simulate the rotation effect. The numerical results are validated with experimentally determined fan curve over broad range of operating conditions. The effect of the foam resistance parameters on the flow characteristics is investigated which serves the rationale for the optimization of these parameters. The model is used to study the sensitivity of the VRB performance to foam parameters using different types of commercially available open-cell reticulated foam.