9 th Annual Conference of the CFD Society of Canada, 27 - 29 May, 2001, Kitchener, Ontario 1 COMPUTATIONAL STUDIES OF FLUID FLOW AND PRESSURE DISTRIBUTIONS IN A SPIRAL GROOVE SEALS Vladimir Kudriavtsev 1 , M. Jack Braun 2 and Robert C. Hendricks 3 vvk@cfdcanada.com, mbraun@uakron.edu, robert.c.hendricks@grc.nasa.gov 1 Principal Engineer, CFD Canada / CERCA, Montreal 2 Professor, University of Akron, Akron, Ohio 3 Principal Scientist, NASA Glenn Research Ceneter, Cleveland, Ohio Key Words: Spiral Groove Seal (SGS), CFD, load capacity, flow visualization, turbomachinery ABSTRACT The Spiral Groove Seal is a self-acting device that uses the fluid flowing between its faces to lift the sealing faces from each other. Thus, it is also referred to as a non-contacting face seal. In this paper we utilized a full 3D Navier-Stokes equations solver (CFD-ACE+) to study the flow patterns inside an inward pumping spiral groove seal CFD-ACE+ (http://www.cfdrc.com ) is a commercial software package that has inherited many advanced features implemented in a research code SCISEAL[1] developed by CFD Research Corporation for NASA Glenn (Lewis) Research Center (1992-96). INTRODUCTION The Spiral Groove Seal (SGS), a typical example of hydrodynamic self-acting device [2,3,4], is presently widely used by the industry in form of cylindrical seals [4], face mechanical seal [5], or even as a form of thrust bearing. The seal assembly of a typical SGS (face seal) is shown in Figs. 1 and 2. Here, the grooves on the outside portion of the stator are oriented such as to pump inward with the pressure gradient [6]. The inward pumping is produced, in this case by the clockwise motion of the rotor. The cylindrical seal vesion of the example shown in Figure 1 has the grooved pattern etched on the stationary cylindrical surface and the seal is divided into two areas. The first low pressure region has grooves that are optimized to produce a maximum stagnation pressure. Grooves are spatially oriented to produce a pumping component in the axial direction. Pressure will increase due to the pumping action and will partially offset the imposed pressure gradient between P high and P low sides [6]. The second region is smooth and serves as the seal dam. This region works in conjunction with the grooved region. As the fluid is pumped through the grooves towards the dam, the pressure increases inside the spiral groove due to the interaction of the rotating flow with the groove sidewalls. Typically, the shaft(or disk) is rotating at speeds in excess of 10,000 rpm, with clearances between the rotating and stationary components below 0.001 inch. The SGSs have dual utilization and are now also actively pursued in advanced bearing designs [7]. The inward pumping spiral groove (face or cylindrical) creates a positive pressure gradient that causes the required sealing effect. The pumping characteristic is most critical and strongly depends on the rotational speed, direction of rotation, groove depth, orientation and shape, groove Figure 1. Example of John Crane’s Face Seal to dam ratio and liquid/gas properties. Possible alternate groove layouts are show in Fig. 3 Existing numerical simulations of SGS are limited mostly to Reynolds equation application [5-9]. However, very strong flow recirculation patterns take place in the groove/dam area (see Fig. 5) and flow formations can be rather complex[10]. Presently NASA developed computational models SPIRALI,