Ball bearing axial load the principle and characteristic of indirect measurement method

1, axial load, the principle of indirect measurement method in the process of aircraft engine design, on the basis of engine rotor axial force and the calculation method of rotor axial force can be divided into axial force and the cavity flow axial force of two parts. , as shown in figure 1, plate cavity axial force for the engine air chamber of the system of the axial load on the rotor system, the sum of flow axial force for engine compressor turbine runner axial load combined. For each of the calculation of axial force components, mainly based on the theorem of momentum. Rotor axial force calculation input parameters are: import static pressure, axial velocity, area of flow channel, nozzle static pressure, axial velocity, area, through the flow mass flow rate, the disc cavity cavity pressure, flow and geometric parameters of the cavity, etc. Ball bearing axial load indirect measurement method based on rotor axial force calculation method, and that the basic idea is to each component of the axial force and the cavity flow to calculate the axial force and superposition. For cavity axial force, through the real-time measurement of engine rotor system related each chamber of the cavity pressure, according to the geometrical size of the corresponding cavity can be calculated. But in the engine bench test, restricted to the feasibility and the limitation of the test system, can't completely measuring chamber pressure required for engine air system, and therefore must be in computing. If can through the cavity of the flow pressure and back pressure. Seal (form, etc. , combined with some experience formulas and fixed way, estimate the cavity pressure, etc. , and through the related calculation processing, can get all the necessary air system static pressure cavity, so as to realize the reality of cavity axial force. When measuring. Measurement is the key to experience formula and parameter selection, selection of the formula and parameters directly affect the cavity axial force calculation precision. In the treatment of the cavity when the axial force, generally ignore the airflow in the cavity flow momentum effect of axial force to the rotor. For flow axial force, through the real-time measurement of compressor, turbine runner related section parameters such as the import and export of static pressure and axial velocity, flow axial force calculation method, which can realize the real-time measuring the flow axial force. The same as the cavity axial force test, usually some cross section parameters cannot directly test. If for some reason makes it hard for the turbine inlet parameters directly measured, but its export by turbine parameters according to the working characteristic of turbine backstepping calculated. In known compressor, turbine runner import and export data, including the static pressure and axial velocity according to engine working line, parts characteristic line, etc. , interpolation and fitting out the import and export of rotor blade per level static pressure and axial velocity, etc. When the engine working in different working conditions, the interpolation formula have bigger difference, so the need for multiple sets of interpolation method, calculated. Then according to the specific algorithm calculating axial force of the rotor blade per level, the last part superposition, real-time measure flow axial force of the rotor system. Measurement is the key to the choice of interpolation and fitting formula and correction. Through the axial force and the cavity flow field of the axial force superposition is engine rotor axial force. When the engine rotor axial force of indirect measurement, in order to real-time display, based on the engine parameters in measuring channel dedicated program for measuring. When using axial load indirect measurement method, requires the engine components, structure, performance, and many other detailed parameters, combined with the feasibility of the testing system, for those who are less direct measurement parameters, need a flexible use of measured parameters, the structure of the engine performance data are derived. For the axial load measurement algorithm is put forward, also need to take a variety of ways to check and correction, eventually form suitable for a particular engine the axial load of indirect measurement method. 2, axial load characteristics of indirect measurement method is compared with other traditional axial load measurement methods, ball bearing axial load mainly has the following advantages: (indirect measurement method 1) The measurement precision and controllable. If there is a higher measuring accuracy, you may need to put forward a comprehensive measuring parameters is calculated. ( 2) Every component of measurable axial load. Ball bearing axial load composed of several component superposition, axial load indirect measurement method can be output each axial force component, favors the engine of the axial force analysis and adjustment. ( 3) Real-time measurement of engine rotor axial force. By axial load, indirect measurement procedures can be real-time display engine when the engine test bench on the size of the axial force, provide the basis for engine condition monitoring. ( 4) Measurement method is simple, do not need to modify the engine structure. The engine bench test, its need to measure more parameters to verify that the engine design level, the method to choose relevant measurement parameters ( Can be appropriately supplement partial parameters) Ball bearing axial load measurement can be achieved. But there is also insufficient, the method of the main is necessary to make more comprehensive on the engine parameter measurement. In engine development phase, can implement a comprehensive parameter measurement; But in batch production stage, cannot meet the requirements of a large number of parameters measurement, need to use other methods to realize measurement of ball bearing axial load.