Experimental Study of the Flow Characteristics of a Cellular Well Seal for Steam Turbines

Abstract

In this paper, a study of the flow characteristics of a seal with a cellular stator is carried out. The rotor had a well surface with a diameter of d = 10 mm and a depth of h = 1 mm. The stator part is made of stamped rings and radial plates, forming a cellular structure with a rectangular cross section. Holes were made on the outer plate to separate moisture into the sealing chamber behind the stator. A series of experiments were carried out with a fixed disk and rotating at different speeds (1000; 2000; 3000 rpm). The results of the construction of consumption characteristics showed that the effect of rotation is negligible. Numerical research at Ansys revealed the complex spatial nature of the gas flow in the flow part of the seal with the formation of reverse vortex flows. In a seal with wells, the vortices in the cells, on the contrary, have a more gentle structure. The strengthening of vortex structures is associated with a changing gradient of the area of the wells, where local acceleration of the main flow occurs, which, in turn, pumps the perturbed flow into the cells. The numerical calculation and field experiment performed have shown the effectiveness of using this seal design for steam turbines, especially in nodes of large axial displacements of the shaft line relative to the housing.