scholarly journals Predicting broadband open rotor noise using analytical simulation

2020 ◽  
pp. 86-91
Author(s):  
И.П. Бойчук ◽  
А.В. Гринек ◽  
А.И. Бойчук
Keyword(s):  
Sound Pressure ◽  
Isotropic Turbulence ◽  
Rotation Speed ◽  
Turbulent Wake ◽  
Broadband Noise ◽  
Homogeneous Isotropic Turbulence ◽  
Rotor Noise ◽  
Analytical Simulation ◽  
Open Rotor ◽  
Infinite Sums

В работе представлено исследование аналитического метода расчета широкополосного шума взаимодействия турбулентного следа, сходящего с лопастей переднего винта, с лопатками заднего. Метод основывается на методе Амита. Нестационарная нагрузка на задний ротор моделируется с помощью теории тонкого профиля. Для вычисления аэродинамических сил используется теория полос. Турбулентный след задается моделью однородной изотропной турбулентности. Такая модель позволяет исследовать влияние количества лопаток, расстояния между винтами и скорости вращения винтов на образование широкополосного шума. В работе предложены алгоритмы расчета уровней звукового давления и звуковой мощности широкополосного шума, а также разработан программный комплекс, использующий среду и язык программирования MATLAB. Показано, что корректировка способа вычисления дискретных турбулентных волновых чисел приводит к уточнению предсказания шума в области 400-700 Гц. Увеличение пределов суммирования при вычислении бесконечных сумм сказывается на точности предсказания шума незначительно. The paper presents a study of the analytical method of broadband rotor-wake/rotor interaction (BRWI) in contrarotating open rotors calculation. The presented method is based on the Amit method. Non-stationary load on the rear rotor is modeled using thin profile theory. The theory of stripes is used to calculate aerodynamic forces. The turbulent wake is given by the homogeneous isotropic turbulence model. This model allows one to study the influence of the blades number, the distance between the rotors and the rotors rotation speed on the broadband noise formation. Algorithms for calculating the sound pressure levels and sound power of broadband noise are proposed. A software package was developed using the MATLAB environment and programming language. It is shown that the discrete turbulent wavenumbers correction for calculating improves the predictions of noise in the 400-700 Hz region. Increasing the summation limits when computing infinite sums has little effect on noise prediction accuracy.

Advanced open rotor noise prediction

2014 ◽  
Vol 118 (1208) ◽  
pp. 1125-1135 ◽  
Author(s):  
M. J. Kingan
Keyword(s):  
High Speed ◽  
Broadband Noise ◽  
Current Status ◽  
Prediction Methods ◽  
Noise Prediction ◽  
Acoustic Data ◽  
Rotor Noise ◽  
Future Challenges ◽  
Open Rotor ◽  
Development And Validation

Abstract The purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting ‘isolated’ and ‘installed’ open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig.

Small-scale energy cascade in homogeneous isotropic turbulence

2019 ◽  
Vol 4 (10) ◽  
Author(s):  
Mohamad Ibrahim Cheikh ◽  
James Chen ◽  
Mingjun Wei
Keyword(s):  
Isotropic Turbulence ◽  
Energy Cascade ◽  
Small Scale ◽  
Homogeneous Isotropic Turbulence

Deterministic forcing of homogeneous, isotropic turbulence

1994 ◽  
Vol 6 (4) ◽  
pp. 1612-1614 ◽  
Author(s):  
Neal P. Sullivan ◽  
Shankar Mahalingam ◽  
Robert M. Kerr
Keyword(s):  
Isotropic Turbulence ◽  
Homogeneous Isotropic Turbulence

scholarly journals Spectral modelling for passive scalar dynamics in homogeneous anisotropic turbulence

2016 ◽  
Vol 799 ◽  
pp. 159-199 ◽  
Author(s):  
A. Briard ◽  
T. Gomez ◽  
C. Cambon
Keyword(s):  
Isotropic Turbulence ◽  
Reynolds Numbers ◽  
Passive Scalar ◽  
Homogeneous Isotropic Turbulence ◽  
Scalar Flux ◽  
Anisotropic Turbulence ◽  
Theoretical Predictions ◽  
High Reynolds ◽  
Shear Driven Flows ◽  
Very High

The present work aims at developing a spectral model for a passive scalar field and its associated scalar flux in homogeneous anisotropic turbulence. This is achieved using the paradigm of eddy-damped quasi-normal Markovian (EDQNM) closure extended to anisotropic flows. In order to assess the validity of this approach, the model is compared to several detailed direct numerical simulations (DNS) and experiments of shear-driven flows and isotropic turbulence with a mean scalar gradient at moderate Reynolds numbers. This anisotropic modelling is then used to investigate the passive scalar dynamics at very high Reynolds numbers. In the framework of homogeneous isotropic turbulence submitted to a mean scalar gradient, decay and growth exponents for the cospectrum and scalar energies are obtained analytically and assessed numerically thanks to EDQNM closure. With the additional presence of a mean shear, the scaling of the scalar flux and passive scalar spectra in the inertial range are investigated and confirm recent theoretical predictions. Finally, it is found that, in shear-driven flows, the small scales of the scalar second-order moments progressively return to isotropy when the Reynolds number increases.

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