A Theoretical And Experimental Study For Hydrostatic Finger Seal

Advanced seal technology of gas turbine is a branch field which was paid great attention to it over the world in recent decade years. The benefits from advanced seal technology have truly reflected in the aspects of gas turbine performance increasing, Specific Fuel Consumption (SFC) decreasing, running and maintaining cost reducing etc.. Finger seal technology is currently a forward research direction of advanced seal technology. By through widely collecting and inquiring the information of this researching field, and on the basis of analyzing the merits and demerits of contacting finger seal and hydrodynamic finger seal, the new idea of hydrostatic finger seal was put forward in this paper. Aimed at the hydrostatic finger seal, the profound research works in theory and test were done, and some satisfactory results are achieved in this paper.1. On the basis of widely studying and analyzing the achievements of finger seal technology that have been achieved, hydrostatic finger seal was bring forward in this paper. The hydrostatic finger seal has a small clearance and have the merits of simpleness in structure, utility in engineering, and good reliability. When compressed air passes through the clearance between hydrostatic pad and coating rotor with high speed, the pressure acts on the working surface of hydrostatic pad was much smaller than inlet air pressure, and this assured that hydrostatic pad has the merit of small displacement. According to this working principle of hydrostatic finger seal, two kinds of finger seal ring and four kinds of coating rotor were designed in this paper. The test hydrostatic finger seal has pressure balanced structure and can be disassembled, by reassembling the test finger seal, other kinds of finger seal was formed and can meeting the test research requirements.2. In order to meet the test research conditions of hydrostatic finger seal, on the basis of existing gas turbine seal test rig, the reform works of control system and measure system of the seal rig were done, the console for equipment operation and data acquisition system were built. Using the operating environment of MCGS (Monitor and Control Generated System), the data acquisition software for seal test rig was developed in this paper, and successfully come true the test data measuring and conserving in real time.3. The features of forces acting on the parts of hydrostatic finger seal were analyzed from the dynamic point of view, and the calculating model of dynamics was set up in this paper. By means of reasonably simplifying the calculating model, the dynamic calculations of considering the contact friction between parts were realized in this paper. In the light of main factors that have important influence on dynamic characters of hydrostatic finger seal, the numerical simulations and analysis were done by using the structural analyzing software of Samcef/Field. The conclusions are that the clamping force, inlet pressure and the fillet radius between hydrostatic pad and stick are factors that have an important influence on dynamic characters of hydrostatic finger seal, and when designing hydrostatic finger seal, the three factors must be synthetically considered.4. The mathematical model of hydrostatic finger seal for fluid-structure interaction (FSI) calculation was put forward in this paper. In the light of structural characteristics of hydrostatic finger seal with small clearance, the mathematical model for FSI calculation, which composed of three dimensional and time averaged N-S equations and linear stress-strain equations, was set up, also the convergent rules were given. The FSI calculations were realized in this paper by using CFX5.7 as the fluid solver engine, and ansys9.0 as the stress-strain solver engine.5. In the light of the main factors that affect leakage and deformation of hydrostatic finger seal, the numerical simulations and analysis were done by using the FSI mathematical model which was put forward in this paper, and the working principle of hydrostatic finger seal was explained by using the theory of vortex dissipating energy. The research conclusions about leakage and deformation achieved in this paper have important meaning to guide the design of hydrostatic finger seal.6. In the light of goal for engineering use of hydrostatic finger seal, the tests of seal performance, seal hysteresis, and wearing characters were done.The conclusions of seal performance test are that hydrostatic finger seal has the characteristic of lower leak level, its leakage is about one third of that of labyrinth seal on the same seal conditions.The conclusions of seal hysteresis test are that the pressure balanced structure designed in this paper can improve seal hysteresis, due to the existing test rig conditions, the ability to improve seal hysteresis wasn't revealed adequately. By means of measuring the pressure of pressure balanced cavity, it indicates that the pressure balanced structure have already realized pressure balance.The conclusions of wearing test are that the wearing effect of friction pairs composed of GH3044 finger and WC coating rotor as well as GH3044 finger and ceramic coating rotor are preferable, and friction pairs composed of GH3044 finger and nitriding rotor are relatively poor.