离心风机方面有着巨大的节能空间,可以获得非常可观的社会和经济效益。陕西风机?中离心通风机的损失类型主要有四种,分别为流动损失、容积损失、轴承摩擦损失和轮盘损失。后两种有时统称为机械损失,因为轴承摩擦损失是轴承旋转摩擦产生的外部机械损失,轮盖损失是由于叶轮旋转时与周围气体摩擦产生的内部机械损失。

Centrifugal fan has huge energy-saving space and can obtain very considerable social and economic benefits. Shaanxi fan? There are four main loss types of centrifugal fan, namely flow loss, volume loss, bearing friction loss and disc loss. The latter two are sometimes collectively referred to as mechanical losses, because the bearing friction loss is the external mechanical loss caused by the bearing rotation friction, and the wheel cover loss is the internal mechanical loss caused by the friction between the impeller and the surrounding gas when the impeller rotates.

1、流动损失

1. Flow loss

陕西风机?主要的损失是流动损失,其根源在于气体的黏性。流动损失可以分为边界层摩擦损失和漩涡损失,后者包含边界层分离、“射流尾迹”和二次流等引起的损失以及通风机在非额定工况下工作,由于气流入口角与叶片入口角之间的差异引起的冲击损失。流动损失与边界层密切相关,一方面边界层加厚会导致边界内气体摩擦损失加大,另一方面当边界层发展到一定程度,靠近壁面的位置将出现倒流,导致边界层脱离壁面而形成分离,从而形成一定涡区,引起较大损失。

Shaanxi fan? The main loss is the flow loss, which is rooted in the viscosity of the gas. The flow loss can be divided into boundary layer friction loss and vortex loss. The latter includes the loss caused by boundary layer separation, "jet wake" and secondary flow, as well as the impact loss caused by the difference between air inlet angle and blade inlet angle when the fan works under non rated working conditions. The flow loss is closely related to the boundary layer. On the one hand, the thickening of the boundary layer will increase the gas friction loss in the boundary. On the other hand, when the boundary layer develops to a certain extent, there will be backflow near the wall, resulting in the separation of the boundary layer from the wall, forming a fixed vortex area and causing great losses.

2、二次流损失

2. Secondary flow loss

在离心叶轮叶道内存在压力梯度,在叶片表面和轮盖轮盘表面边界层内的流体形成的惯性力不能与叶道内的压力梯度平衡,从而在边界层内产生由压力面流向吸力面的流动。该流动与叶道内的主流方向垂直,称为二次流。二次流是轮盖和轮盘表面边界层内靠压力面的低速流体微团被吸走,并使吸力面的边界层变厚导致分离,引起损失。射流-尾迹现象的产生原因是吸力面上的边界层分离影响到主流区的流动,在压力面附近的形成挤压区域,流速较高称为射流。而在吸力面附近则相对速度较低,称为尾迹。

There is a pressure gradient in the blade path of centrifugal impeller. The inertial force formed by the fluid in the boundary layer on the blade surface and the wheel cover disc surface cannot be balanced with the pressure gradient in the blade path, resulting in the flow from the pressure surface to the suction surface in the boundary layer. The flow is perpendicular to the main flow direction in the blade channel, which is called secondary flow. Secondary flow is that the low-speed fluid micro mass near the pressure surface in the boundary layer on the surface of wheel cover and wheel disc is sucked away, and the boundary layer on the suction surface becomes thicker, resulting in separation and loss. The reason for the jet wake phenomenon is that the boundary layer separation on the suction surface affects the flow in the mainstream area. A squeeze area is formed near the pressure surface, and the high velocity is called jet. The relative velocity near the suction surface is low, which is called wake.

集流器与叶轮入口之间存在一定的间隙,从叶轮流出的气体有少部分会经过该间隙流回叶轮入口,这种由间隙引起的损失称为容积损失。轮盘和轮盖的摩擦损失会造成功率损失但是不降低压力。另外,用于屋顶通风和风机墙的无蜗壳风机叶轮出口处的动能没有转化为静压,当气流冲出叶轮后动能被全部损失掉,还存在动压损失。

There is a certain gap between the collector and the impeller inlet, and a small part of the gas flowing out of the impeller will flow back to the impeller inlet through the gap. This loss caused by the gap is called volume loss. The friction loss between the wheel disc and the wheel cover will cause power loss, but does not reduce the pressure. In addition, the kinetic energy at the outlet of the volute free fan impeller for roof ventilation and fan wall is not converted into static pressure. When the air flow rushes out of the impeller, the kinetic energy is completely lost, and there is also dynamic pressure loss.

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This article is provided by Shaanxi centrifugal fan manufacturer. Our website is: http://www.sdyqtc.com We will serve you with wholehearted enthusiasm. Welcome to visit

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