Dynamic Response Of High Speed Flexible Rotor Due To Sudden Large Unbalance

The structure vibration response of the rotor and the installation section caused by sudden unbalance load due to blade out of the high-speed flexible rotor has been the focus in the field of aviation engine development. This paper is mainly about the sudden unbalance response characteristics of the rotor due to blade out of the high-speed flexible rotor. To this end, the main researches are as follows:(1) A simplified rotor-bearing system is modeled use LS-DYNA to carry out the blade out simulation analysis. Further simulation is analyzed with different blade out mass and blade out velocities. Unbalance response of the rotor and the load ability of the support bearing are analyzed in detail under various weights and blade out speeds condition. Failure mode of the rotor shaft is twist. Rub between the rotor and the limit bearing is classified as follow two states:one is the discontinuous interaction that causes twist of the rotor. The deformation can restore to equilibrium state after the rub to decrease unbalance response. Another one is the continuous interaction that the rotor doesn’t restore back and the shaft break at the weakest region. The two conditions occur in sequence. Studies have shown that with the increase of the distance from the axis point to the limit support, the protective effect of the limit support is more weak. Three different gap values are compared to study the vibration response. With the increase of the gap value, the load between rotor and limit support firstly increase and then decrease. However, The protective effect may decrease with large gap value. It is concluded that load is not the only factor related to failure. Axial displacement of the rotor should also be considered.(2) Dynamic response of high speed flexible rotor due to sudden large unbalance is studied with the use of high speed rotational tester,ZUST6D. Blade out tests of various weights and various speeds are carried out. It is found that the amplitude of sudden rotor vibration and the load on limit support is in the same magnitude due to either single blade out or full blade out. However, more danger is brought to high speed flexible rotor due to single blade out. Large unbalance on long duration on limit support-support base-protection ring-hanger make the system vibrate severely. This response can lead to failure of the installation section on real engine. The higher rotor speed and unbalance mass can lead to more severe vibration response. (3) Horizontal high speed rotation tester is built mainly with the turbocharger for overall vibration response research due to fan blade out. Initial set-up and power-on test is completed and improvement suggestions are made.