Backward curved centrifugal impeller is a type of centrifugal fan, but when it rotates, there is a pressure difference across the impeller blades. On the convex side of the impeller blades, a force is generated in the air during the rotary motion of the impeller to generate a positive pressure. At the same time, the impeller blades push the air outwards and leave it radially.
On the concave side of the backward curved centrifugal impeller blade, when the fan rotates, a negative pressure is generated and air is sucked into the gap between the blades. Then, in a continuous process, this air is driven outward by the blades below. The suction side of the impeller blade sucks air in the center of the fan, causing a change in the direction of airflow between the inlet and the 90o exhaust port.
It can be seen that the best operating area for bending the centrifugal impeller backward is the middle part of its performance characteristics. When operating in the middle pressure and intermediate flow, the backward bending centrifugal impeller presents the best working condition, and can bring the ideal use effect to the user.
The advantage of using a backward curved centrifugal impeller is that it has no stall point, which means that no point on the impeller characteristic curve is inoperable, so it can also be used in the plenum or incorporated into the rolling space to guide the air flow out. This is the other type of Fan impeller does not have the characteristics.
When the required operating point falls in the area of the intermediate system pressure, the intermediate volumetric flow over the characteristics of the backward curved centrifugal impeller should be taken into account and should be chosen within the central range of its flow characteristics. In addition, the air bent on the inlet side of the centrifugal impeller should be kept smooth and laminar to maximize the efficiency of the impeller blades.
The use of an air intake ring in the backward bending of the centrifugal impeller) overlaps the inlet cone of the impeller, helping to eliminate air flow disturbances through the fan, reducing turbulence-induced noise, minimizing work load at the operating point and maximizing efficiency.
However, the load characteristics allow fans to be installed without rollers, and the impeller design satisfies the highest static efficiency of all fan types. This means that the backward-bending fan is a flexible, adjustable fan design that can be installed in a wide range. Use within range.