Hole-pattern seals performance evaluation using computational fluid dynamics and design of experiment techniques

A main goal of noncontacting mechanical seals is to provide minimal leakage during operation. This may be achieved by specifying a small clearance between the mating faces that is just enough to avoid rubbing contact while allowing some tolerable leakage. The amount of leakage flow is reduced through the acceleration and deceleration of the fluid through a tortuous path, so the sealing performance depends on the geometric characteristics of the leakage path. This study focuses on annular hole-pattern seals, which are noncontacting mechanical seals commonly used in high pressure compressors. A design of experiments (DOE) approach is used to investigate the effects of various geometric variables on the leakage rate of a hole-pattern seal during normal operating conditions. The design space, defined by the ranges of hole diameter, hole depth, axial space between holes and number of holes in circumferential direction, is discretized using the simple random sampling method. Then, steady-state computational fluid dynamics (CFD) simulations are performed at each design point to evaluate seal performance. To better understand the sensitivity of the hole-pattern seal leakage rate with respect to design variables selected, response surfaces are built through its values at design points using quadratic polynomial fitting. The results show that the optimal solution had a better leakage control ability over the base model design. It is believed that the results of this study will assist in improving the design of annular hole-pattern seals.