Does the space between the vanes and the cam ring increase or decrease at the discharge port in a vane pump?

In a vane pump, as the fluid is pumped from the inlet to the discharge port, the space between the vanes and the cam ring decreases at the discharge port. This phenomenon occurs because the vanes are forced outward by centrifugal force as the pump rotates. At the discharge side of the pump, the pressure within the pumping chamber is higher, which causes the vanes to be pushed more tightly against the cam ring.

This reduction of space at the discharge port is crucial for maintaining the efficiency and performance of the pump, as it helps to effectively seal the high-pressure fluid, preventing backflow and ensuring that the fluid is properly directed through the discharge port. Understanding this behavior is important for diagnosing issues related to pump performance and for designing systems that utilize vane pumps.