Orifice Characteristics Of Static Pressure Dry Gas Seal And End Face Thermal Deformation Analysis

According to the relevant literature at home and abroad, introduction is done on the development status, the working principle and the typical structure of static pressure dry gas seal. Influence of the orifice characteristics on the seal performance is analysed and numerical calculation is carried out on the end face flow field.Based on the static gas-lubricated thrust bearing theory, the gas lubrication Reynolds equation of stable state static pressure and the orifice flow control equation are built. In order to improve the seal performance, the orifice flow term is introduced to the Reynolds equation and an improved N-S equation is established. And formulas of the main parameters of the opening force and the gas film stiffness are derived.Corresponding computer program is compiled in MATLAB using the functional extremum algorithm and the finite element method,numerical calculations is carried out under changes of the orifice diameter and the end gap. Emphasized analysis is done on the influence of gas film thickness, source pressure, orifice number and diameter on the opening force and film stiffness, and temperature distribution on the end face. The results show that a significant pressure drop is formed as the seal gas flows through the orifice, the film stiffness decreases with the increase of orifice diameter and increases with the increase of source pressure; pressure on the end is maximum around the orifice and decreases gradually to the surrounding; the opening force decreases as the end gap increases and increases with the source pressure increases. When the face clearance in the range 3-13μm, the opening force decreases rapidly with increasing clearance and with a larger gas film stiffness on the end.According to the research conditions and methods on aspects of seal thermal field, seal deformation and optimization by the related domestic and overseas data,the heat-structure coupling theory is established as the research method of thermal analysis on the end face of static pressure dry gas seal.Based on the assumption and simplification of the heat balance model, the solid conduction differencial equation without internal heat source is established in the stable state two dimensional cylindrical coordinates. Temperature field model of the rotary and static rings is built in ANSYS and solved to obtain the temperature distribution rules in the rings and the thermal-structural coupled deformation is solved to get the thermal deformation rules. Through simulation of the seal face thermal deformation in the stirred tank reactor, analysis is done on the influence of different parameters including the working condition, the material and the structure on the axial and radial thermal deformation and the deformation conicity on the end face, and on the main factors affecting thermal deformation. Discussion is carried out on the commonly used optimization method and optimization scheme is brought forward according to the thermal deformation compensation theory on rotating and static ring, the optimized ring is analysed again using the thermal-structure coupled deformation method verify ing the feasibility of this optimization scheme.