Design And Manufacture And Dynamics Analysis Of A High-Speed Drag Equipment For The Airborne Generator

As the power source of entire avionics system,airborne generators determine whether the aircraft can fly safely in the air directly,so the performance test for airborne generators is particularly important.Usually the airborne generator is powered by the main engine connected to the aircraft,but for safety,the test for generators can not be carried out during the flight,so it’s need to develop a the drag device running on the ground to drive the airborne generator operated at the required speed to test whether its performance parameters meet the relevant requirements.For this reason,the paper aims to design and manufacture a set of generator drag equipment,and study the dynamic characteristics of the rotor system through the finite element analysis software.First of all,the author designs the axis system parts as a reasonable structure and check the strength for the relevant parts.And determine the reasonable range of tolerances for the associated mating parts to ensure the concentricity between the rotors during installation.At the same time,as the measured motor needs to cool by the oil,the author also designs the relevant sealing parts to ensure all the oil sealed in them.And the structure of the drag device under the shaft part and the structure of the oil vehicle are also designed.Secondly,through the modal analysis of the rotor system,the author extracts the natural frequency,vibration mode,critical speed and other related modal information.It is concluded that the natural frequency of the rotor system is all above 300 Hz.It means that the system does not resonate at the maximum speed of 12,000 RPM,and it can run stably.When the front axle of the generator is installed a bearing with large stiffness,the natural frequency of the system can be increased,so that the critical speed is further away from the working speed range.Again,for the rotor misalignment force,the author studies the rotor system for a harmonic response analysis.The analysis founds that when the generator front axle installed a bearing with the stiffness of 75,000,000 Newton per meter,the vibration amplitude of the generator near the place which is connected with the coupling increases from 37μm to 11μm at the speed of 12,000 RPM.That’s to say,the amount of vibration amplitude reduces by 70 percent.Finally,after installation and commissioning,the test determines the rotor system can operate stably for a long time during the speed range from 0 to12000 RPM.