Development Of Liquid Rocket Engine Rotating-loop Rotational Speed Measuring System

The rotating-loop is an important part of the liquid rocket engine Turbo pump.Before the rotating-loop product is delivered,it must pass the ultra-high speed measurement to assess its working characteristics.Based on the background of a certain type of liquid rocket engine,the research on the rotating speed measurement system of the coil is carried out,and a test bed for measuring the rotating speed of the coil of a certain type of liquid rocket engine is established.The test system must meet the requirements of an index with a maximum speed of not less than 95000 r/min and a measurement accuracy of not less than 0.5 ‰.Theoretical analysis and calculation are carried out for the specific measurement object of the rotating rotating-loop.The magnetic field of the magnetic coil is measured by magnetic meter on the magnetic shaft end screw when the pole is facing the coil.According to the measurement results,the magnetic induction strength formula is fitted,and the total magnetic flux formula of the qualifying ring is derived.The effective value and peak value of the corresponding voltage signal are obtained by numerical calculation.Based on the principle of speed measurement,the speed measurement system of the rotating-loop is built,and the sub-systems such as high-speed electric spindle,cooling lubrication system,motion control system,data acquisition system,software test system,and electromagnetic protection system are designed in detail.High speed electric Spindle is the core part of the whole measurement system.The structural strength of the spindle is predicted by numerical simulation.Eight dynamic coefficients of the spindle at different rotational speeds at an eccentricity of 0.3 are obtained,and the first order of the rotor.Second order vibration type and critical speed.On the basis of theoretical analysis and numerical simulation,a test bed for measuring coil speed of liquid rocket engine was established.The interference of noise to the measured signal is effectively reduced by the method of extracting the base frequency of the signal.Through the multi-wheel pulse test,the measurement accuracy of the speed measurement system was assessed,and the measurement accuracy reached 0.1 ‰.The influence of different sampling frequency and signal length on the measurement accuracy was analyzed.The test of the test stand and the test of the test stand with load were carried out respectively,and the safety and reliability of the test bed at different spindle speed were evaluated and the validity of the measured data.The rotating rotating-loop speed measurement system was successfully put into use after passing the examination platform.A total of 53 rotating-loop products were measured,and the effectiveness and safety of the measuring system were further verified.Each measuring speed fluctuation was less than 10r/min.The maximum speed reaches 100,000 r/min,and the measurement value of the test system is similar to the numerical calculation value.