Case 2. Backward curved fan: - Efficiency only slightly less than airfoil fans. 3: Example of a uni-directional fan, with straight blades. - Efficiency slightly lower than airfoil fan. A pusher style fan mounts in front of the radiator and pushes air ... Verify direction of fan blade matches the corresponding image below, it may be necessary to flip the fan blade … Fan rotation is determined by looking at the fan from the drive end. Question Fan direction advice: Cases & Cooling: 9: Dec 9, 2020: Similar threads; 1. Deep blades allow efficient expansion within blade passages. The speed of the truck is the wheel velocity and thrown ball is the velocity of the the air leaving the tip of the blade. The principle used for determining the direction of rotation is “backwardly curved blades… For DWDI or Arrangement 3 SWSI fans, it is the side of the fan housing at which the belt drive sheave is mounted. Fig. The profile and axial designs of a volute tongue have great influences on the internal flow conditions and aerodynamic performance of a forward-curved blade centrifugal fan. In the example shown below, the fan rotates in a clockwise direction. 10 to 16 single-thickness blades curved or inclined away from direction of rotation. Type 2, Open Radial Blade with Back Plate blower wheels are designed for conveying powdery or granular material and long stringy paper trimmings or fibers. June 15, 1998; Share on Facebook. Why is it that when you look at the spinning propeller of a plane or fan, at a certain speed, the blades seem to move backwards? They produce relatively medium to high airflow at static pressures. R. RavenSEAL Diamond Member. 4: The “backwardly curved blades” principle is used in determining the direction of rotation for angled or curved blades. The backward inclined centrifugal fans offer three standard blade types – flat single thickness, curved single thickness and curved airfoil. CURVED BLADE ELECTRIC FANS Selecting Pusher Or Puller Style Operation Determine if the fan will be installed as a pusher or puller style. Share on Twitter. Backward Inclined Fans. The fan blades are curved, convex (outward curved) on one side, concave (inward curved) on the other. Fig. The drive end is is the side of the fan housing through which the fan or motor shaft protrudes. The shape of your blades and the direction they travel will define the performance characteristics of your fan. Air will flow from the convex side to the concave side. A forward curved centrifugal fan is characterised by its cylindrical shape and lots of small blades on the circumference of the impeller. For centrifugal fans, discharge is the direction the fan outlet points. The blades are generally heavier and larger than forward curved and move away from the direction of wheel rotation. Type 1, Shrouded Radial Blade blower wheels are designed to deliver higher pressures for pressurizing, blow-off systems and long duct or pipe runs. The pitcher turns around and throws in a direction opposite the direction of the truck otherwise same as before. This is because of the vector sums of the two velocities. Backward curved fans have blades with leading edge curved or inclined away from the direction of rotation. Fig 3 shows the velocity diagram for the air flowing into the fan (inlet) and out of it (outlet). This corresponds to a forward curved blade fan. Available in Models PB, SPB, PBS, RBE and some HP-Series II blowers. Air leaves impeller at velocity less than tip speed.