Research On Sealing Charateristics Of An Aeroengine Typical Flanged Casing Structure

The leakage of aero-engine casing flanges affects the efficiency and pressure ratio of an aero-engine remarkably. The high temperature gas leakage from flanges of an aero-engine casing accounts for a significant proportion in the overall gas leakage of an aircraft-engine. The study has an important significance in improving the performance of aero-engines.In this article, a combined method of numerical simulation and experiment was used in the analysis and study of factors which affects leakage of aero engine casing flanges. Based on fracture mechanics, the relationship between the leakage pressure and stress of aero engine casing flanges was investigated. A 3D finite element model of an aero-engine casing flange was established,the stress characteristics of an experiment product imposed external loads was figured out, the variation tendency of leakage pressure in different flange structure parameters(bolt numbers,flange thickness, diameter of the bolt)and different preloads of bolts and loading scheme were studied. The results shows that the leakage pressure grows with the increase of the bolt number and preloads, decreases with the rise of the edge thickness. The sealing characteristics of cross loading scheme are better than progressive loading scheme.In the aspect of experiment, a sealing structure test bench of a typical aero-engine casing flange was built up, and the influnces of bolt preload and loading scheme were sdudied. In the experiment, gas was injected into the casing until the pressure achiving a target value, and the pressure reduces from maximum to minimum with a droping rate from large to small smoothly; The medium temperature increases at first, reduces then, and balances to the environmental temperature in the end. The leakage pressure rise in a linear change with the bolt preload increase and the other conditions remain the same. After four wheel loading, the uniformity of bolt preload for JIS B 2251 manner and progressive manner is better than ASME PCC-1 manner, and the sealing performance of JIS B 2251 manner and progressive manner scheme is better than ASME PCC-1 manner, while the workload of JIS B 2251 is the least. JIS B 2251 manner is the best loading scheme.