Validation of a Modal Work Approach for Forced Response Analysis of Bladed Disks

Abstract

The paper describes a numerical method based on a modal work approach to evaluate the forced response of bladed disks and its validation against numerical results obtained by a commercial FEM code. Forcing functions caused by rotor–stator interactions are extracted from CFD unsteady solutions properly decomposed in time and space to separate the spinning perturbation acting on the bladed disk in a cyclic environment. The method was firstly applied on a dummy test case with cyclic symmetry where the forcing function distributions were arbitrarily selected: comparisons for resonance and out of resonance conditions revealed an excellent agreement between the two numerical methods. Finally, the validation was extended to a more realistic test case representative of a low-pressure turbine bladed rotor subjected to the wakes of two upstream rows: an IGV with low blade count and a stator row. The results show a good agreement and suggest computing the forced response problem on the finer CFD blade surface grid to achieve a better accuracy. The successful validation of the method, closely linked to the CFD environment, creates the opportunity to include the tool in an integrated multi-objective procedure able to account for aeromechanical aspects.

Improving Aeromechanical Performance of Compressor Rotor Blisk with Topology Optimization

“…The unsteady forcing resulting at the end of each unsteady run was then further Fourier decomposed in space, in the circumferential direction, to obtain a single traveling wave exciting a corresponding mode shape in a cyclic environment, as predicted by the interference diagram (Figure 7). To do so, the Fourier coefficients in time on the blade surface were circumferentially decomposed on homologous points on adjacent blades (one on each blade, for a row pitch) by means of the in-house tool named OutDFT [33] with the following formula:…”

Jet Engine Turbine Mechanical Properties Prediction by Using Progressive Numerical Methods

“…As the training algorithm is scaled, a conjugate gradient (SCG) for the supervised learning is used. This algorithm updates the weight and bias values according to the scaled conjugate gradient method [33][34][35]. The algorithm is able to train any ANN as long as its weight, net input and transfer functions have derivative functions.…”

“…The results are mapped using ANSYS software, and transient thermal analyses are performed (Figure 7); the results from these thermal analyses are used for the mechanical stress analyses. Regime 35 is used to illustrate the results of the transient thermal analyses for one cyclic region [33]. In Figure 7, the temperature fields can be seen for regime 35.…”

“…The CFD analyses are performed to define the re temperatures, pressures and mechanical properties (deformation sults are mapped using ANSYS software, and transient thermal (Figure 7); the results from these thermal analyses are used for the yses. Regime 35 is used to illustrate the results of the transient th cyclic region [33]. In Figure 7, the temperature fields can be seen f tion time for the transient thermal analysis for one load step is 18.…”

Effect of clocking on entropy noise generation within an aeronautical high pressure turbine stage

“…The high level of the code parallelization, achieved by means of a hybrid openMP/MPI code architecture [26] was exploited to reduce the computational time. The computational framework was extensively validated against several turbine and compressor configurations for aerodynamic, aeromechanical and aeroacoustic applications [27,28,29].…”