Performance Characteristics of High-Pressure Centrifugal Exhaust Fans

Performance Characteristics of High-Pressure Centrifugal Exhaust Fans

High-pressure centrifugal exhaust fans operate on the principle of converting kinetic energy into potential energy. A high-speed rotating impeller accelerates the gas flow, then decelerates and redirects it to transform kinetic energy into potential energy (pressure).In these fans, gas enters the impeller axially, exits radially after passing through the impeller, and enters the diffuser. Within the diffuser, the gas flow direction changes, the duct cross-sectional area increases, and the gas velocity slows down, thereby converting kinetic energy into pressure energy. Pressure increase is primarily generated by the impeller. The high-pressure centrifugal blower employs a continuous diffusion process, using a counterflow device to direct airflow to the next impeller stage, thereby generating high pressure. The operating principle of high-pressure centrifugal exhaust fans is fundamentally similar to that of turbo propellers. However, due to minimal pressure variation and low gas flow rates, gas behavior typically requires no consideration. The gas is treated as an incompressible fluid. Motor side: The propeller rotates clockwise. This is termed a right-hand fan. The propeller rotates counterclockwise. This is termed a left-hand fan. High-pressure centrifugal exhaust fans are essentially variable-flow, constant-pressure devices. Under constant-speed conditions, their theoretical pressure-flow curve is linear; actual characteristic curves inevitably curve due to internal losses. The pressure generated by high-pressure centrifugal exhaust fans is significantly affected by changes in intake temperature and air density. At a specific intake volume, the generated pressure decreases as air temperature drops (air density decreases). The specified pressure-flow characteristic curve includes output and flow characteristic curves. When operating at a specific speed, if the intake temperature decreases relative to the specified flow rate, the required output increases.