Flow and plate motion in compressor valves

The Basic Valve Theory is based on steady ow characteristics. Therefore unsteady ow conditions in the model valve have been considered in order to assess effects of unsteadiness on the performance of the Basic Valve Theory. The instantaneous gas force was predicted rather accurately by the theory. However, it has also been observed that ow hystersis effects are present. These effects are postulated to be caused by a periodically detaching and reattaching ow at the seat. This hypothesis has been enforced by predicting the valve state variables, employing the Extended Valve Theory. The Extended Valve Theory takes into account the ow inertia in the port and the plate speed. However, further exploration of the validity of the Extended Valve Theory for a broader range of parameters has to be performed. For a commercial compressor valve also unsteady ow experiments have been conducted. For the limiter almost inelastic plate collisions have been observed. The collisions of the plate with the seat resulted in severe rocking effects. These effects are postulated to be caused by the absence of gas damping, the relatively low spring force and the position of the guiding holes in the plate.