Study On Sealing Mechanism And Local Feature Design Of Gas Path Of Aero-Engine Compressor

The development trend of aero-engines with high performance and high thrust-to-weight ratio puts forward higher requirements on compressors.Improving the sealing performance of the gas path sealing technology is an effect method to increase the working efficiency of compressor.The inter-stage leakage losses and the tip-leakage losses are important sources of internal flow loss in the compressor.The selection of sealing methods is the key to reduce leakage losses and improve efficiency.In this paper,the method of numerical simulation is used to study the sealing positions of the compressor stage and the blade tip clearance,which provides a theoretical reference for the application in engineering practice.For the compressor inter-stage seal,the sealing mechanism of labyrinth-honeycomb seal was studied and a multi-factor linear regression model was established.First,the honeycomb structure was designed as hexagonal,square,and circular honeycomb to compare with smooth land under different sealing gaps,pressure ratios and rotational speeds.Based on this,an orthogonal experimental design is proposed to study the effects and interactions of nine structural labyrinth-hexagonal honeycomb parameters on the leakage characteristics.Finally,the leakage results of these simulation experiments with orthogonal characteristic were collected to build a multi-factor linear regression model relating the geometric design variables to predict the amount of leakage.The results show that the sealing effect of labyrinth-honeycomb seal is better under the condition of large clearance、high pressure and high speed,and the circular honeycomb seal is more advantageous.Considering their metal processing performance and geometric mechanical properties,the hexagonal honeycomb structure is more practical.Orthogonal experiment results show that the gap and pressure ratio have a significant impact on the leakage coefficient.The linear regression equation was compared and verified by another 20 sets of CFD simulation results,which showed a better prediction effect on the leakage of the labyrinth-honeycomb seal.For the tip clearance sealing,the wear of the abradable coating on the casing will increase the tip clearance and roughness.In order to reveal the influence mechanism of aerodynamic performance degradation caused by coating wear,the numerical simulation was conducted on the Rotor37 of the casing with different scraping conditions.The results show that when the coating is scraped at low speed,the use of low-hardness or high-hardness coatings will minimize compressor performance degradation;when scraping the coating at medium and high speeds,the use of high-hardness coatings is more helpful to the performance of the compressor.The isentropic efficiency and outlet flow rate of the compressor decrease with the increase of the scraping gap and roughness,and the decrease can reach up to 1.78% and 0.83%,while the pressure ratio is almost unchanged.When the wear gap increases and the deepest position of the scraping is moved forward,a stronger tip leakage vortex will be formed,which will interfere with the shock wave and cause greater tip loss.When the roughness of the wear area increases,there is no significant compressor performance degradation.The isentropic efficiency is more sensitive to the roughness changes,but the maximum decrease is only 0.38%.When the roughness of the wear area increases,the turbulent fluctuations in the near wall area are strengthened and the air flow separation is easier,which makes the aerodynamic characteristics of the compressor shift to the direction of low flow.