Abstract
Unsteady flow around an oscillating plate cascade and that through a single compressor rotor subject to vibration have been computationally studied, aimed at examining the predictive ability of two low fidelity frequency methods compared with a high fidelity time-domain solution method for aeroelasticity. The computational solutions demonstrate the capabilities of the frequency domain methods compared with the nonlinear time-domain solution method in capturing small perturbations in the unsteady flow. They also show the great advantage of significant CPU time saving by the frequency methods over the nonlinear time method. Comparisons of two different frequency methods, nonlinear harmonic and phase solution method, show that these methods can produce different results due to the differences in numeric and physical conditioning. The results obtained using phase solutions method are in better agreement with the nonlinear time-domain solution. This is because the same numeric and physical conditioning are used in both the nonlinear time-domain method and phase solution frequency domain method.
Highlights
The blading aerodynamic design has long been employing steady flow methods as they are highly efficient and robust [1,2,3]
This paper focuses on two relatively simple cases, flow around a 3D flat plate oscillating cascade and through a compressor rotor subject to vibration, to demonstrate the validity and compare the effectiveness of three computational methods
When the high fidelity nonlinear time-domain solution is compared with the low fidelity phase solution method, one can consistently find the difference in the modeling fidelity without interference from differences in numeric
Summary
The blading aerodynamic design has long been employing steady flow methods as they are highly efficient and robust [1,2,3]. Advanced frequency domain such as nonlinear harmonic and phase solution methodologies have been developed which on the one hand is efficient for an unsteady flow solution for aeromechanics and on the other hand can be used for blading design optimization without much extra effort. While the other time-linearized harmonic methods express the whole flow solution in a Fourier series, this method is based on casting the unsteady flow equations into a set of steady-like equations at a series of phases of a period of unsteadiness. A brief description of the governing equations and the time and frequency domain methods is given ; this is followed by the prediction of flow over an oscillating plate and flow through a single compressor rotor using various methods. By doing so, when the high fidelity nonlinear time-domain solution is compared with the low fidelity frequency domain, one can consistently find the difference in the modeling fidelity without interference from differences in numeric
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