Modeling of Cyclic Life for Compressor Rotor of Gas Turbine Engine Taking Into Account Production Deviations

Abstract

The regional aircraft with a turbofan gas turbine engine, created in Russia, is successfully operated in the world market. Further increase of the life and reduction of the cost of the life cycle are necessary to ensure the competitive advantages of the engine. One of the units limiting the engine life is the compressor rotor. The cyclic life of the rotor depends on many factors: the stress-strain state in critical zones, the life of the material under low-cycle loading, the regime of engine operation, production deviations (within tolerances), etc. In order to verify the influence of geometry deviations, the calculations of the model with nominal dimensions and the model with the most unfavorable geometric dimensions (worst cases) have been carried out. The obtained influence coefficients for geometric and weight tolerances are then used for probabilistic modeling of stresses in the critical zone. Rotor speed and gas loads on the blades for different flight missions and engine wear are determined from the corresponding aerodynamic calculations taking into account the actual flight cycles (takeoff, reduction, reverse) and are also used for stress recalculations. The subsequent calculation of the rotor cyclic life and the resource assessment is carried out taking into account the spread of the material low-cycle fatigue by probabilistic modeling of the rotor geometry and weight loads. A preliminary assessment of the coefficients of tolerances influence on stress in the critical zone can be used to select the optimal (in terms of life) tolerances at the design stage. Taking into account the actual geometric and weight parameters can allow estimating the stress and expected life of each manufactured rotor.

Calculation and Experimental Study of Low-Cycle Fatigue of Gas Turbine Engines Booster Drum

“…A modern approach to strength calculations requires the preparation of a parametric model of the part, which allows taking into account changes in individual parameters (geometric dimensions and material properties, as well as SSE fixation during tests) and conducts automated rebuilding of the model, which reduces the time for preparation of calculations [5,[13][14][15].…”

“…The next stage is to conduct a series of calculations of a three-dimensional sub-model of the rotor sector containing the critical area. A parametric model is also developed for this stage [5]. The calculation takes into account the boundary conditions from the previous axisymmetric calculation, contact interaction of blades and drum, temperatures and centrifugal loads.…”

“…Calculations of these models showed that the difference in stresses for the nominal model and the model with the worst tolerances could be up to 10.8%. It can be assumed that a random (uncorrelated) scatter of tolerances on geometric dimensions of the rotor and the weight of blades with a probability of 0.99% can reduce the maximum stresses [5].…”

“…With the selected force angle and force magnitude, SSE stress gradient i possible to the booster drum gradient (Figure 9). In this case, the difference between the change in stresses along the thic tested specimen and the stresses in the rotating drum with blades is checked [5] ( In this case, the difference between the change in stresses along the thickness in the tested specimen and the stresses in the rotating drum with blades is checked [5] (Figure 10). In contact pairs that include SSE, the contact type is set to frictional with a coefficient of 0.05, the parts for which a bolted connection is provided are set to contact.…”

“…LCF life zone for titanium alloys over 10,000 cycles is not very studied. Most companies' durability models are based on extrapolation of LCF data in a range of up to 10 4 cycles or multi-cycle fatigue results in the range of 10 5 cycles and above [5].…”