Investigations on the Discharge and Total Temperature Increase Characteristics of the Labyrinth Seals With Honeycomb and Smooth Lands

Abstract

The viscous work generated by the rotating components of a seal not only represents a direct loss of power but also causes an increase in the total temperature of fluid (windage effect). In order to study the discharge and total temperature increase characteristics of the stepped labyrinth seals with smooth and honeycomb lands, 3D Reynolds-averaged Navier–Stokes solutions from CFX is used in this work. At first, the influences of the inlet preswirl, leakage flow rate, and rotational speed on the total temperature increase in the convergent and divergent stepped labyrinth seals with smooth and honeycomb lands are conducted. The obtained 3D numerical results are well in agreement with the referenced experimental data. It shows that the utilized numerical approach has sufficient precision to predict the total temperature increase in seals. Then, a range of pressure ratios and four sizes of sealing clearance are performed to investigate the effects of sealing clearances and pressure ratio impact on the discharge and total temperature increase of the stepped labyrinth seals with honeycomb and smooth liners.

Prediction of the windage heating effect in steam turbine labyrinth seals

“…The pressure ratio π influences the windage heating: the presented correlation shows that the windage power is increased at higher pressure ratios. This is in agreement with Yan et al (2009). The reason for this behaviour is that the square of the flow velocity influences the wall shear.…”

“…pressure ratio, geometry, axial Reynolds number, circumferential Mach number and fluid parameters mostly influence the windage and leakage behavior. Yan et al (2009) analyze the influence of honeycomb structures, applied to the stator, on windage heating behavior numerically. The labyrinth investigated is again a stepped labyrinth with four fins.…”

“…Since the axial velocity component influences the windage heating effect (Millward and Edwards, 1994;Denecke et al, 2005;Yan et al, 2009), a maximum axial flow velocity c ax between rotor and fin is calculated from:…”

Validation of a CFD Model of a Labyrinth Seal for Low Pressure Turbines Using a Fluid-Thermal Tool Tuned Through Experimental Measurements

“…CFD analyses, concerning labyrinth seals in both smooth and honeycomb configuration, are presented also by Yan et al [7][8][9][10][11]. The outcomes of their numerical analyses were compared with the experimental data available in the papers by Denecke et al [6,12].…”

Dimensionless Numbers Relationships for Outer Air Seal of Low Pressure Turbine

“…The authors also indicated that accurate measurements within such small devices are extremely difficult to complete, so that that the windage heating uncertainty was estimated to lie in the 2-30% range. Their work allowed Yan et al [7] to carry further numerical studies of stepped IAS with and without the honeycomb. Those authors have shown a good agreement of their simulations with the experiments from Denecke et al [6]; they further provided additional characterization of the seal windage heating and leakage flow.…”