scholarly journals Aeroacoustic Investigation of Passive and Active Control on Cavity Flowfields Using Delayed Detached Eddy Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yu Liu ◽  
Yong Shi ◽  
Mingbo Tong ◽  
Fei Zhao ◽  
Binqi Chen
Keyword(s):  
Active Control ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Passive Control ◽  
Cfd Simulation ◽  
Pressure Level ◽  
Control Methods ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

In the present study, CFD simulation with delayed detached eddy simulation (DDES) is performed to investigate an open cavity at Mach 0.85. A clean cavity and cavity with passive and active control methods, including sawtooth spoiler, flat-top spoiler, crossflow rod, and steady leading edge blowing, are analyzed. The results obtained from all the control methods are compared with clean cavity, and all the flow control methods show positive effect on the overall sound pressure level reduction with the decrement up to 8 dB. The effect of active control on sound pressure level in the cavity is much better than that of passive control, with the magnitude of tone noise decreasing by 20-30 dB. The main focus of this investigation is to test the noise suppression effect by passive and active control methods.

Prediction of Aeroacoustic and Control over a Cavity by Delayed Detached Eddy Simulation

2014 ◽  
Vol 598 ◽  
pp. 505-509 ◽  
Author(s):  
Yu Liu ◽  
Ming Bo Tong
Keyword(s):  
Sound Pressure ◽  
Noise Suppression ◽  
Cfd Simulation ◽  
Leading Edge ◽  
Pressure Level ◽  
Detached Eddy Simulation ◽  
Suppression Effect ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
And Control

In the present study CFD simulation with delayed detached eddy simulation (DDES) are performed to investigate an open cavity at Mach 0.85. Two cavity configurations, clean cavity and cavity with a leading-edge saw tooth spoiler, are modeled. The results obtained from clean cavity prediction are compared with experimental sound pressure level (SPL) data from QinetiQ, UK. Furthermore, comparisons are made with the predicted SPL between the two configurations. The main focuses of this investigation are to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect by a saw tooth spoiler.

Investigation of turbulence-induced quadrupole source acoustic characteristics of a three-dimensional hydrofoil

2020 ◽  
Vol 34 (14) ◽  
pp. 2050145
Author(s):  
Rennian Li ◽  
Wenna Liang ◽  
Wei Han ◽  
Hui Quan ◽  
Rong Guo ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Three Dimensional ◽  
Sound Field ◽  
Leading Edge ◽  
Pressure Level ◽  
Acoustic Characteristics ◽  
Eddy Simulation ◽  
Unsteady Fluid

In order to investigate the turbulence-induced acoustic characteristics of hydrofoils, the flow and sound field for a model NH-15-18-1 asymmetric hydrofoil were calculated based on the mixed method of large eddy simulation (LES) with Lighthill analogy theory. Unsteady fluid turbulent stress source around the hydrofoil were selected as the inducements of quadrupole sound. The average velocity along the mainstream direction was calculated for different Reynolds numbers [Formula: see text]. Compared to experimental measurements, good agreement was seen over a range of [Formula: see text]. The results showed that the larger the [Formula: see text], the larger the vortex intensity, the shorter the vortex initial shedding position to the leading edge of the hydrofoil, and the higher the vortex shedding frequency [Formula: see text]. The maximum sound pressure level (SPL) of the hydrofoil was located at the trailing edge and wake of the hydrofoil, which coincided with the velocity curl [Formula: see text] distribution of the flow field. The maximum SPL of the sound field was consistent with the location of the vortex shedding. There were quadratic positive correlations between the total sound pressure level (TSPL) and the maximum value of the vortex intensity [Formula: see text] and velocity curl, which verified that shedding and diffusion of vortices are the fundamental cause of the generation of the quadrupole source noise.

Grid Requirements for Multiscale Resolution in Separated Unsteady High Speed Turbulent Flows

2006 ◽  
Author(s):  
D. Basu ◽  
A. Hamed ◽  
K. Das
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Turbulent Flows ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Pressure Fluctuations ◽  
Pressure Level ◽  
Navier Stokes ◽  
Detached Eddy Simulation

This study deals with the computational grid requirements in multiscale simulations of separated turbulent flows at high Reynolds number. The two-equation k-ε based DES (Detached Eddy Simulation) model is implemented in a full 3-D Navier-Stokes solver and numerical results are presented for transonic flow solution over an open cavity. Results for the vorticity, pressure fluctuations, SPL (Sound Pressure level) spectra and for modeled and resolved TKE (Turbulent Kinetic Energy) are presented and compared with available experimental data and with LES results. The results indicate that grid resolution significantly influences the resolved scales and the peak amplitude of the unsteady sound pressure level (SPL) and turbulent kinetic energy spectra.

Computational investigation of noise interaction for a nano counter-rotating rotor in a static condition

2018 ◽  
Vol 07 (01n02) ◽  
pp. 1850004
Author(s):  
Zhen Liu ◽  
Chen Bu ◽  
Xiangxu Kong ◽  
Dong Yang ◽  
Bingfei Li
Keyword(s):  
Flow Field ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Static Condition ◽  
Pressure Level ◽  
Tip Vortex ◽  
Field Analysis ◽  
Aeroacoustic Noise ◽  
Eddy Simulation ◽  
Coaxial Rotor

The interaction between the upper and lower rotors greatly influences the aeroacoustic characteristics of a counter-rotating nano-coaxial rotor. To study this influence, a numerical investigation was carried out. The unsteady flow field of a single upper rotor was first studied with a large-eddy simulation computational fluid dynamics method coupled with a sliding-mesh technique. The Ffowcs Williams–Hawking equation method was used to investigate the aeroacoustic characteristics of the upper rotor based on the flow field. An experimental setup was established to validate the computational approach. The experimental results matched well with the computational results. Additionally, results show that the peak value of the total sound pressure level appeared near the blade tip, which verified that the tip vortex was one of the most important sources of rotor noise. Then the aeroacoustic noise of the nano-coaxial rotor was studied numerically. It was found that the total sound pressure level of the nano-coaxial rotor was greater than that of the upper rotor. Flow field analysis showed that the shedding vortices of the upper rotor interacted with the lower rotor, resulting in a blade–vortex interaction. It was evident that the aeroacoustic noise was enhanced by the interference between the upper and lower rotors.

Active Control of Structural Sound Radiation in an Acoustic Enclosure Using Distributed Point Force Actuators

2014 ◽  
Vol 1082 ◽  
pp. 517-520
Author(s):  
Da Lin Chen ◽  
Nan Chen
Keyword(s):  
Active Control ◽  
Sound Pressure Level ◽  
Cooperative Control ◽  
Sound Pressure ◽  
Control Method ◽  
Sound Radiation ◽  
Sound Field ◽  
Pressure Level ◽  
Point Force ◽  
Flexible Plates

This paper demonstrates an investigation about the active control of sound radiation in the enclosure cavity consists of two flexible plates. One of the flexible plates is driven by a point force to generate the primary sound field in the cavity, and using some point forces which are located at different locations on the receiving plate to suppressing the panel vibration and then to minimum the cavity sound pressure level (SPL); meanwhile some actuators are located on the other panel surfaces to reduce the sound pressure level at some frequencies that can’t be well reduced by only effect on one panel. The better result shows the possibility of applying distributed cooperative control method to the structural-acoustic coupled system.

Shape Optimization of High-Speed Train Pantograph Insulators for Low Aerodynamic Noise

2012 ◽  
Vol 249-250 ◽  
pp. 646-651
Author(s):  
Xiao Yan Yang ◽  
You Gang Xiao ◽  
Yu Shi
Keyword(s):  
Shape Optimization ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Pressure Level ◽  
Aerodynamic Noise ◽  
High Speed Train ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Elliptical Section

With large eddy simulation(LES) and Lighthill-Curle acoustic theory, the aerodynamic noises radiated from pantograph insulators with rectangular, circular, elliptical section were calculated, and the optimal pantograph insulator shape was obtained. The results show that in the same model, the sound pressure level (SPL) spectrum at different monitoring points are basically the same, but the amplitude is different. In different models, the SPL spectrum are different. As for rectangular, circular, elliptical section insulators, the frequency with maximum SPL reduces gradually. For reducing aerodynamic noise, the elliptical section insulator is optimal, and the long elliptical axis should be consistent with air flow. The pantograph with bigger and less components is helpful to reduce the aerodynamic noise.

CFD Simulation of a Twin-Screw Ship Self-Propulsion Using DDES-Overset Method

2019 ◽  
Author(s):  
Jianhua Wang ◽  
Decheng Wan
Keyword(s):  
Cfd Simulation ◽  
Ship Hull ◽  
The Self ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Ship Model ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Twin Screw ◽  
Cfd Method

Abstract Rotating propellers and moving rudders are necessary for the simulation of free running ship with the purpose of resolving detailed flow interaction. In the present work, CFD method is used to numerically investigate self-propulsion behavior for a twin-screw fully appended ship. The simulation conditions are following the experiment performed at IIHR. The benchmark ship model ONR Tumblehome is used for all the numerical computations. Overset grids are used to fully discretize the ship hull, twin propellers and rudders. Self-propulsion simulation is carried out using a PI controller to achieve target ship speed of Fr = 0.20 in calm water and the ship model is free to trim and sinkage. All the numerical calculations are carried out by the in-house CFD solver naoe-FOAM-SJTU. Unlike most previous studies based on RANS method, the present self-propulsion simulations adopt the Delayed Detached-Eddy-Simulation (DDES) approach to resolve the complex flow around ship hull, propeller and rudder. The main parameters of the self-propulsion as well as flow visualizations are presented. The predicted results are compared with previous RANS data and the available experimental data. The comparison with the experiment is satisfactory and the flow field shows that the present DDES-overset method can give more flow details for the self-propulsion condition.

Numerical Investigations of Transonic Cavity Flow Control Using Steady and Pulsed Fluidic Injection

2005 ◽  
Author(s):  
K. Das ◽  
A. Hamed ◽  
D. Basu
Keyword(s):  
Kinetic Energy ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Stokes Equations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Pressure Level ◽  
Navier Stokes ◽  
Detached Eddy Simulation

A numerical study is conducted to investigate steady and pulsed fluidic actuation in transonic flow over an open cavity. Numerical results are obtained for the unsteady three-dimensional flow with three different steady mass injection rates and one pulsed injection upstream of the cavity. The simulations are carried out using the full 3-D Navier Stokes equations with the two-equation k-ε based Detached Eddy Simulation (DES) model to calculate the flow and acoustic fields. Computational results are presented for unsteady pressure fluctuations, vorticity contours and kinetic energy profiles at different injection ratios. The sound pressure level (SPL) and the kinetic energy spectra highlight the effectiveness of actuation in tone attenuation at peak frequencies. The computed sound pressure level (SPL) spectra with and without injection are compared with available experimental data and LES predictions.

Experimental and numerical studies on Aeolian tone from D-shaped cylinder

2017 ◽  
Vol 232 (22) ◽  
pp. 4007-4018
Author(s):  
T Yamagata ◽  
N Saito ◽  
N Fujisawa
Keyword(s):  
Circular Cylinder ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Cross Sectional ◽  
Velocity Fluctuations ◽  
Fluid Forces ◽  
Eddy Simulation ◽  
Unsteady Fluid ◽  
Sectional Shape

Aeolian tone generated from a D-shaped cylinder in a stream was studied experimentally and numerically for various width-to-height ratios of the cross-sectional shape. The sound pressure level and unsteady fluid forces were measured experimentally for a circular cylinder and D-shaped cylinders with width-to-height ratios of 0.5, 1, and 1.5. The experimental results revealed that the Aeolian tone and lift fluctuation of the D-shaped cylinders were smaller than those of the circular cylinder. Flow structures around the circular and D-shaped cylinders were investigated by using large eddy simulation to understand the mechanism of the reduction of Aeolian tone from the D-shaped cylinders. The numerical results indicated that the D-shaped cylinder with a width-to-height ratio of 0.5 showed similar velocity fluctuations with the circular cylinder, but the shortening of the streamwise length resulted in a reduction of the sound pressure level. Moreover, the velocity fluctuations in the wake decreased in the D-shaped cylinders with width-to-height ratios of 1 and 1.5, resulting from suppression of the vortex shedding near the cylinder.

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