| Aero gas turbine engine, as the core power plant of modern military aircraft and civil aircraft, itsperformance is a key factor which determines the reliability, operating costs, performance of airplane.In order to meet the requirement of supersonic aircraft, the technical requirements, such as highpressure ratio, high thrust-weight ratio, high turbine inlet temperature and etc, are highlighted in thedesign stage of engine, which also make some faults in the running process of engine in return, forexample, vibration, strength, fatigue and others. The large vibration of engine may results in the rub atthe small gap (seals, tip) between the rotor and the stator, the overload in the bearing, the discomfortof passenger, the indicator shaking in the panel, even endanger the flight security, which lead tocatastrophic accidents. With the development of modern technology and the pursuit of aero-enginehaving high thrust-weight ratio and high speed, most aero-engine’s operating speed is relatively high,while the casing shell is thin, so the coupling vibration between casing and rotor is increasing, whichform a more complex rotor-casing coupling system, therefore it is necessary to study the vibrationproblem from the whole engine model. The whole engine finite element model can not only reflect thecharacteristics of rotor dynamic stiffness, but also consider the local vibration of casing and thecoupling effects between rotor and stator, which truly reflects the dynamic characteristics of rotorsystem. As the structure of aero-engine is complicated, the model considering casing is not onlydifficult to modeling, but also slow to be calculated, therefore, in this paper, based on the aero-enginerotor tester, the dynamic stiffness test which substitute the casing finite element model is got and usedfor the whole engine vibration analysis as follows:(1) The experimental stiffness test analysis is conducted on the casing test device through thehammer method with four test solutions, and finally vertical and horizontal dynamic stiffness ofcasing are got.(2) A three-dimensional solid model that simulates the casing is created in Pro/e, after messed bySolid185solid element, exerted constraint according to actual installation conditions, athree-dimensional finite element model of casing can be got in ANSYS, finally, calculating stiffness isgot and is compared with the experiment results.(3) Modal test is conducted on the rotor system supported by two methods through the hammermethod, and model test of machine is conducted by hammer and sinusoidal scanning method, theresults got by different test methods are compared with each other. Modal analysis towards to rotor system is conducted in ANSYS, and the result is compared with that got by modal test, which is usedfor the model correction.(4) The whole engine finite element model such as rotor-static stiffness, rotor-dynamic stiffnessand rotor-casing are built for the critical speed analysis. Finally, the results obtained by three wholeengine models are compared with each other, which show that the critical speed value got by therotor-dynamic stiffness finite element model is close to the critical speed value got by the rotor-casingfinite element model, but the computing speed of the rotor-dynamic stiffness finite element model isfaster than that of the rotor-casing finite element model. |
