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    Oil temperature analysis of brush seals
    (2008) Duran, Ertuğrul Tolga; Aksit, Mahmut Faruk; Doğu, Yahya
    Due to their superior performance and stable leakage characteristics, brush seals are one of the dynamic seals used in oil and oil mist applications in aero-engines and turbines. The viscous medium between the high speed rotor surface and brush seal bristles generates a hydrodynamic lifting force that determines seal clearance and leakage rate in oil sealing applications. The analytical solution to bristle lifting force can be obtained by using Reynolds formulation. However, there is a strong dependence on oil temperature and viscosity. This work presents a solution to oil temperature using nonlinear pressure distribution. Starting with continuity and Navier Stokes equations, temperature and nonlinear pressure distribution is derived by solving the thermal energy and reduced continuity equations simultaneously. Results of oil temperature estimates using nonlinear pressure analysis are compared with the results of a previous work using linear pressure assumption. Findings indicate that for low rotor surface speeds oil temperature distribution is almost the same for both linear and nonlinear pressure cases. Difference in oil temperature estimates increases with increasing rotor surface speeds. Copyright © 2007 by ASME.
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    A Study of Cloth Seal Leakage Performance Based on Geometry and Pressure Load
    (MDPI, 2020) Gorgun, Erdem; Aksit, Mahmut Faruk; Dogu, Yahya
    Metal cloth seals have been used increasingly in gas turbines due to their flexibility and superior leakage performance. Leakage performance of a metal cloth seal depends on operating conditions, slot and geometric dimensions. These parameters need to be investigated for the best leakage performance. In this study, pressure drop and critical geometric parameters of typical cloth seal form are investigated with an experimental setup. Slot depth, cloth width, sealing gap, shim thickness, surface roughness, pressure drop, offset and mismatch are selected parameters for the screening experiments. Sixteen experiments were conducted following a two-level Resolution IV fractional factorial experiment design for eight parameters. The results indicated that strong parameters for the leakage performance are pressure drop, cloth width, slot depth and offset. Leakage rate is increased with an increase in slot depth, gap, shim thickness, pressure drop and mismatch. During screening experiments, the experiment with minimum flow rate has 86% lower leakage rate than the experiment with maximum flow rate. For main experiments, a Box-Behnken experiment design is applied to analyze nonlinear effects of four strong parameters on the leakage rate. A closed-form equation is derived based on the data and presented in this study.