Development of finger seal for gas turbine applications

Abstract

newlineIncreasing demand for improved efficiency and increased operating life requires newlineconcentrating on optimising leakage flow. The reason is leakage flow interacts with the newlinemain flow causing a reduction in the turbine s efficiency. This leakage flow also causes newlineflow excitation which will affect the rotor dynamics of the shaft. newlineLeakage flow has to be controlled, for certain parameters can be varied, and those newlineparameters are the clearance between the seal and rotor, the introduction of a pressure newlinewedge between the pad surface and the rotor, operating pressure and so on. newlineThe research is about leakage flow control, which is done by designing, analysing and newlineoptimizing the finger seal configuration. To accomplish this goal research covers newlineautonomous yet interrelated areas of solid mechanics, fluid flow analysis and experimental newlineleakage test. newlineSolid mechanics exhibited the relationship between the stiffness of the finger and the finger newlineseal design. The same was also used to confirm the relationship between the finger newlinedimensions and stiffness of the finger, to achieve the compliant motion of the finger for the newlinehydrodynamic lifting of the finger. newlineFluid analysis was a solid-fluid interaction used to characterise under pad pressure and newlineforce. It was also used to analyse fluid leakage flow varying the rotor speed and high- newlineto-low pressure differential. To analyse the fluid behaviour when a taper is introduced in the newlinepad along the axial direction in all three laminates, which will create a vortex flow of fluid newlinein the gap, causing the reduction of leakage along the axial direction. newlineThe experimental analysis provided the data for the leakage assessment for the new seal newlineconfiguration. The data included the measuring of test section pressure and fluid flow which newlinegave leakage values. Experiments were conducted for new seal configuration for different newlinepressure differentials, maintaining rotor speed constant and varying the speed of rotor while newlinekeeping pressure difference constant