INCORRECT CONTACT OF SCREW SURFACES AND NUMERICAL SOLUTION OF THE LEAKAGE FLOW THROUGH THE ARISEN GAP

The article deals with the incorrect contact of screw surfaces which create tooth faces of screw-type machine rotors and is concerned about the turbulent computation of a gas leakage through a two-dimensional model of an undesirable gap caused by the incorrect contact of rotor teeth screw surfaces. The incorrect contact of rotor teeth screw surfaces, considered in this study, is caused by a parallel displacement of the male rotor axis. The problem of the leakage flow through the two-dimensional model of the undesirable gap is solved as a non-stationary turbulent compressible Newtonian fluid flow with ideal gas properties. The turbulent flow is assumed to be statistically steady and the mathematical model is described by the non-linear conservative system of the compressible Favre-averaged Navier-Stokes equations. Its numerical solution is performed using the cell-centred finite volume formulation of the explicit two-step TVD MacCormack scheme which is proposed by Causon and is defined on a structured quadrilateral grid. To simulate the turbulence effects the algebraic Baldwin-Lomax turbulence model is implemented into the developed numerical code.