Simulation Analysis Of Micro-gap Flow Field In Spiral Groove Gas Seal

With the increasingly harsh conditions of fluid mechanical working conditions,the requirements for dynamic sealing of the shaft end of the equipment have also increased.The original sealed products cannot meet the requirements for high-parameter fluid mechanical shaft end seals.In this paper,according to the characteristics of gas turbine high-parameter operating conditions,the cylindrical spiral groove gas film seal that can be applied to extreme conditions is proposed.According to the structural characteristics of cylindrical spiral groove gas film sealing,through the method of CFD numerical simulation,a three-dimensional cylindrical spiral groove micro-gap gas film calculation domain model was first established using SolidWorks modeling software and the DM module of Workbench;The grid partitioning software ICEM CFD's unique block mapping technology divides the high-quality computational domain grid;the three-dimensional flow field of the micro-gap is numerically simulated by the fluid field simulation software Fluent,and the operating parameters,structural parameters and spiral grooves are changed.The parameters of the trough are simulated one by one to obtain the corresponding leakage and buoyancy.Finally,comparative analysis obtains the reasonable range of structure parameters and spiral groove parameters.According to the above process,the following analysis rules are obtained:The calculation results show that when the eccentricity is 0.5,with the rotation of the rotor,the film pressure rises by 0.218 MPa.The root of the thinnest area of the film is the maximum pressure;The flow velocity appears the maximum in the thickest area of the film.The overall flow velocity and the pressure are inversely proportional;The comparative analysis of the non-eccentric structural air film model shows that there is no pressure increase;Comparing the film pressure distribution under different eccentricity,It is concluded that the eccentric structure and spiral groove geometry are cylindrical spiral grooves.For the operating parameters,buoyancy and leakage increase with speed and differential pressure.When the differential pressure at the boundary does not change,the buoyancy rises by 44.26N.When the rotation speed changes from 6000-36000 rpm,the leakage amount increases by 0.56×10^-4kg·s^-1,When the rotation speed changs within the range of 24000-33000rpm,the buoyancy and leakage occur that increase amplitude is reduced,and the seal tends to be stable.When the rotation speed is constant,the buoyancy force rises by 331.71N with the boundary pressure difference changing from 0.1MPa to 0.6MPa,and the leakage amount increases by 1.2063×10^-4kg·s^-1.And the overall trend is linear growth.The comparison found that the pressure difference has a greater impact on buoyancy and leakage.For structural parameters,both buoyancy and leakage increase with increasing eccentricity;buoyancy decreases with increasing average film thickness,and leakage increases with increasing average film thickness;buoyancy increases with increase of the seal width,and the overall trend tends to increase linearly,and the leakage decreases with the increase of the seal width.The influence of the structural parameters on the sealing performance is compared and analyzed.The eccentricity and the seal width have a greater influence on the buoyancy.The average film thickness and the seal width have a greater influence on the leakage.Compared with the operating parameters and the trough structure parameters,the structural parameters have more obvious influence on the sealing performance.However,taking into account the actual project,the recommended value range of the optimal structural parameters is:eccentricity 0.5-0.7,the average film thickness is guaranteed below 20?m,and the sealing width is selected from 30mm to 50mm.Through the analysis of the groove parameters with different spiral grooves,it can be concluded that the increase of the number of grooves and the ratio of the groove width will monotonously increase the buoyancy,but within a certain range,the buoyancy force will tend to be stable;the groove depth and the groove The increase of the long and spiral angle will cause the buoyancy of the film to increase first and then decrease,so the buoyancy force has a maximum value within a certain range;the increase of the number of grooves will reduce the leakage,and the depth of the groove and the width of the groove The increase of the ratio,slot length and spiral angle will increase the leakage,but for different spiral groove parameters,there is a relatively stable change trend in the leakage process.In summary,the optimal spiral groove parameters are obtained:the number of grooves is 16²0,the depth of grooves is10¹5?m,the ratio of the groove width is 0.8⁰.1,the length of the spiral groove is24²8mm,and the spiral angle is 30°⁴0°.The research work in this paper provides a reference for the theoretical research and engineering application of the cylindrical spiral groove film sealing.Through experimental research,the buoyancy and leakage of the two sets of specimens with initial parameters of spiral groove and optimization parameter spiral groove were tested.The numerical simulation values and test values of the initial parameters and the initial parameters of spiral groove were compared and analyzed.And optimization parameters Spiral groove test results of two sets of test pieces.Under different pressure conditions,the initial parameters of the spiral groove test and numerical simulation values fit higher,so the numerical simulation results have a certain degree of rationality and authenticity;optimization parameters spiral groove sealing performance are better than The initial parameters of the spiral groove,at the same time,can suppress the adverse effects of the sealing device.The research work provides a reference for the theoretical research and engineering application of the cylindrical spiral groove gas film seal in this paper.