scholarly journals A time-domain method for prediction of noise radiated from supersonic rotating sources in a moving medium

2018 ◽  
Vol 474 (2210) ◽  
pp. 20170089 ◽  
Author(s):  
Zhongjie Huang ◽  
Leonidas Siozos-Rousoulis ◽  
Tim De Troyer ◽  
Ghader Ghorbaniasl
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Impulsive Noise ◽  
Time Domain Method ◽  
Special Treatment ◽  
Noise Prediction ◽  
Moving Medium ◽  
Domain Method ◽  
Emission Surface ◽  
Flow Effects

This paper presents a time-domain method for noise prediction of supersonic rotating sources in a moving medium. The proposed approach can be interpreted as an extensive time-domain solution for the convected permeable Ffowcs Williams and Hawkings equation, which is capable of avoiding the Doppler singularity. The solution requires special treatment for construction of the emission surface. The derived formula can explicitly and efficiently account for subsonic uniform constant flow effects on radiated noise. Implementation of the methodology is realized through the Isom thickness noise case and high-speed impulsive noise prediction from helicopter rotors.

scholarly journals A Finite-Difference Wavenumber-Time Domain Method for Sound Field Prediction in a Uniformly Moving Medium

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bichun Dong ◽  
Runmei Zhang ◽  
Chuanyang Yu ◽  
Huan Li
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Sound Pressure ◽  
Sound Field ◽  
Time Domain Method ◽  
Practical Significance ◽  
Moving Medium ◽  
Domain Method ◽  
Aero Engines ◽  
The Stability

Sound field prediction has practical significance in the control of noise generated by sources in a flow, for example, the noise in aero-engines and ventilation systems. Aiming at accurate and flexible prediction of time-dependent sound field, a finite-difference wavenumber-time domain method for sound field prediction in a uniformly moving medium is proposed. The method is based on the second-order convective wave equation, and the wavenumber-time domain representation of the sound pressure field on one plane is forward propagated via a derived recursive expression. In this paper, the recursive expression is first deduced, and then numerical stability and dispersion of the proposed method are analyzed, based on which the stability condition is given and the correction of dispersion related to the transition frequency is made. Numerical simulations are conducted to test the performance of the proposed method, and the results show that the method is valid and robust at different Mach numbers.

A Mixed Frequency/Time-Domain Method to Evaluate the Performance of Semi-Active Steering Damper Control Strategies During Challenging Maneuvers

2011 ◽  
Author(s):  
Pierpaolo De Filippi ◽  
Sergio M. Savaresi
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Control Strategies ◽  
Time Domain Method ◽  
Mixed Frequency ◽  
Active Steering ◽  
Domain Method ◽  
Damper Control ◽  
The Stability ◽  
Wheeled Vehicles

This work presents the validation of control strategies for a semi-active steering damper aimed at improving the stability of two-wheeled vehicles by controlling the weave and wobble modes. A mixed frequency/time-domain method is introduced to evaluate the performance of the control strategies. The proposed cost functions allow one to evaluate the influence of the algorithms on the damping of the weave and wobble modes and also the overall performance in terms of stability of the steering assembly and of the chassis. The performance of the control algorithms is assessed on a multibody motorcycle simulator considering three challenging maneuvers that excite both the weave and wobble modes, such as kick-back and strong braking while cornering at high speed.

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