Numerical Assessment of 2D Aeroacoustic Simulations for Landing Gear

2018 ◽  
Author(s):  
Sultan I. Alqash ◽  
Kamran Behdinan
Keyword(s):  
Acoustic Field ◽  
Numerical Study ◽  
Near Field ◽  
Three Dimensional ◽  
Aerodynamic Noise ◽  
Design Stage ◽  
Acoustic Analogy ◽  
Ansys Fluent ◽  
2D Flow ◽  
Field Noise

Landing gears (LG) are primarily designed to support the entire loads of an aircraft during landing, taxiing, and taking off. From aerodynamic design prospective, many of the LG components are exposed to the air flow giving rise to what so-called aerodynamic noise. Numerical study of complex systems such as LG as a three-dimensional (3D) model is not only CPU and memory consuming, but also it is way beyond the demand of industries for quick estimate during the design stage [1–3]. To understand the underlying physics of the flow induced noise, a two-dimensional (2D) flow past a circular cylinder is simulated using ANSYS Fluent. Two different Reynolds numbers, Re = 150 and 90000 are examined. For low Re, two distinct numerical conditions relevant to steady and unsteady flow are simulated and compared to examine the effect of the time dependency on the acoustic field. At high Re, the acoustic field is computed using the built-in Ffowcs William and Hawkings (FW-H) acoustic analogy solver in Fluent. The results show the importance of including the unsteady state term to extract the flow data. The far-field noise prediction is found to be highly dependent on the location of the near-field data.

scholarly journals Predicting Far-Field Noise Generated by a Landing Gear Using Multiple Two-Dimensional Simulations

2019 ◽  
Vol 9 (21) ◽  
pp. 4485
Author(s):  
Sultan Alqash ◽  
Sharvari Dhote ◽  
Kamran Behdinan
Keyword(s):  
Cross Sections ◽  
Near Field ◽  
Computational Cost ◽  
Numerical Data ◽  
Landing Gear ◽  
Design Stage ◽  
Far Field ◽  
Two Dimensional ◽  
Acoustic Analogy ◽  
Field Noise

In this paper, a new approach is proposed to predict the far-field noise of a landing gear (LG) based on near-field flow data obtained from multiple two-dimensional (2D) simulations. The LG consists of many bluff bodies with various shapes and sizes. The analysis begins with dividing the LG structure into multiple 2D cross-sections (C-Ss) representing different configurations. The C-Ss locations are selected based on the number of components, sizes, and geometric complexities. The 2D Computational Fluid Dynamics (CFD) analysis for each C-S is carried out first to obtain the acoustic source data. The Ffowcs Williams and Hawkings acoustic analogy (FW-H) is then used to predict the far-field noise. To compensate for the third dimension, a source correlation length (SCL) is assumed based on a perfectly correlated flow. The overall noise of the LG is calculated as the incoherent sum of the predicted noise from all C-Ss. Flow over a circular cylinder is then studied to examine the effect of the 2D CFD results on the predicted noise. The results are in good agreement with reported experimental and numerical data. However, the Strouhal number (St) is over-predicted. The proposed approach provides a reasonable estimation of the LG far-field noise at a low computational cost. Thus, it has the potential to be used as a quick tool to predict the far-field noise from an LG during the design stage.

Noise Prediction for Multi-Element Airfoil Based on FW-H Equation

2011 ◽  
Vol 52-54 ◽  
pp. 1388-1393
Author(s):  
Jun Tao ◽  
Gang Sun ◽  
Ying Hu ◽  
Miao Zhang
Keyword(s):  
Flow Field ◽  
Sound Pressure ◽  
Near Field ◽  
Pressure Level ◽  
Aerodynamic Noise ◽  
Noise Prediction ◽  
Far Field ◽  
Acoustic Analogy ◽  
Acoustic Information ◽  
Good Agreement

In this article, four observation points are selected in the flow field when predicting aerodynamic noise of a multi-element airfoil for both a coarser grid and a finer grid. Numerical simulation of N-S equations is employed to obtain near-field acoustic information, then far-field acoustic information is obtained through acoustic analogy theory combined with FW-H equation. Computation indicates: the codes calculate the flow field in good agreement with the experimental data; The finer the grid is, the more stable the calculated sound pressure level (SPL) is and the more regularly d(SPL)/d(St) varies.

scholarly journals Sound generation in a mixing layer

1997 ◽  
Vol 330 ◽  
pp. 375-409 ◽  
Author(s):  
TIM COLONIUS ◽  
SANJIVA K. LELE ◽  
PARVIZ MOIN
Keyword(s):  
Acoustic Field ◽  
Stokes Equations ◽  
Near Field ◽  
Mixing Layer ◽  
Navier Stokes ◽  
Far Field ◽  
Source Terms ◽  
Acoustic Analogy ◽  
Navier Stokes Equations ◽  
Acoustic Sources

The sound generated by vortex pairing in a two-dimensional compressible mixing layer is investigated. Direct numerical simulations (DNS) of the Navier–Stokes equations are used to compute both the near-field region and a portion of the acoustic field. The acoustic analogy due to Lilley (1974) is also solved with acoustic sources determined from the near-field data of the DNS. It is shown that several commonly made simplifications to the acoustic sources can lead to erroneous predictions for the acoustic field. Predictions based on the quadrupole form of the source terms derived by Goldstein (1976a, 1984) are in excellent agreement with the acoustic field from the DNS. However, despite the low Mach number of the flow, the acoustic far field generated by the vortex pairings cannot be described by considering compact quadrupole sources. The acoustic sources have the form of modulated wave packets and the acoustic far field is described by a superdirective model (Crighton & Huerre 1990). The presence of flow–acoustic interactions in the computed source terms causes the acoustic field predicted by the acoustic analogy to be very sensitive to small changes in the description of the source.

scholarly journals Three-dimensional numerical study of thermal exchanges in different geometry sections of mini-channels using three different nanoparticles

10.30544/455 ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 103-119
Author(s):  
Kamel Chadi ◽  
Nourredine Belghar ◽  
Belhi Guerira ◽  
Aissam Messaoudi
Keyword(s):  
Reynolds Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Three Dimensional ◽  
Numerical Results ◽  
Junction Temperature ◽  
Ansys Fluent ◽  
Cooling Fluid ◽  
Mini Channels ◽  
Exchange Surface

In the present work, we have studied the thermal exchanges of different geometry sections of mini-channels of a cooler numerically. Particularly, we have chosen a mini channels cooler copper for cooling an electronic chip IGBT. In our simulation of three-dimensional (3D), we have compared the numerical results for the different forms of the proposed mini-channels and the three different types of nano-fluids by using the Cu-water, the Ag-water, and the Diamond-water with a volume fraction of 0.02%. The numerical results are obtained by choosing a Reynolds number (Re) between 100 and 900 and considering that the flow regime is stationary. The simulation was performed using commercial software, ANSYS-Fluent 15.0. The results obtained show that the increase of the exchange surface between the walls of the mini channels and the cooling fluid makes increases the heat exchange coefficient and the improvement of the maximum junction temperature of the electronic chip IGBT with the increase of the Reynolds number. The choice of nanoparticles has considerable effects on improving the heat transfer and the maximum junction temperature of the chip IGBT.

Prediction of dipole sources and aeroacoustics field for tandem cylinder flow field based on DBEM/hybrid LES

2021 ◽  
Vol 20 (1-2) ◽  
pp. 157-173
Author(s):  
Zhengyu Zheng
Keyword(s):  
Frequency Response ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Aerodynamic Noise ◽  
Cylinder Surface ◽  
Acoustic Analogy ◽  
Sound Sources ◽  
Noise Interference ◽  
Eddy Simulation ◽  
Dipole Sources

In this paper, the DBEM/Hybrid LES（Directly Boundary Element Method/Hybrid Large Eddy Simulation）technique is applied to predict the aerodynamic noise generated by tandem circular cylinders immersed in a three-dimensional turbulent flow. Utilizing the Lighthill's Acoustic Analogy, the flow pressure fluctuation near the surface of the cylinder is converted into acoustic dipole sources. Taking the dipole sound sources as the actual sound sources, the aeroacoustic field is simulated and analyzed by DBEM. The research shows that: The strong dipole sources are distributed in the collision zone of the downstream cylindrical surface, where the upstream cylinder's shedding vortex colliding to downstream cylinder surface. Both of the amplitude-frequency response and the phase-frequency response of dipole acoustic source are obtained, which is helpful for further research on aerodynamics noise interference and suppression. Good comparisons are obtained between numerical results and BART (Basic Aerodynamic Research Tunnel) experimental data published by NASA.

Prediction of Rail and Bridge Noise in Near- and Far-Field: A Combined 2.5-Dimensional and Two-Dimensional Method

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
X. D. Song ◽  
Q. Li ◽  
D. J. Wu
Keyword(s):  
Interaction Analysis ◽  
Near Field ◽  
Three Dimensional ◽  
Shielding Effect ◽  
Far Field ◽  
Acoustic Model ◽  
Two Dimensional ◽  
Box Girder ◽  
Total Noise ◽  
Field Noise

Bridge noise and rail noise induced by passing trains should be included while estimating low- and medium-frequency (20–1000 Hz) noise in railway viaducts. However, the prediction of bridge noise and rail noise using a three-dimensional (3D) acoustic model is not efficient, especially for far-field points. In this study, a combined 2.5-dimensional (2.5D) and two-dimensional (2D) method is proposed to predict bridge noise and rail noise in both the near- and far-field. First, the near-field noise is obtained by combining the 2.5D acoustic model and a 3D vehicle–track–bridge interaction analysis. Then, the 2D method is used to estimate the attenuation of bridge noise and rail noise in the far-field, and the accuracy is validated through comparison with the 2.5D method. Third, the near-field points are treated as reference sources, and the noise at far-field points is predicted by combining the 2.5D and 2D methods. Finally, the proposed method is used to predict the bridge noise and rail noise for a box girder and a U-shaped girder. The spatial distribution of the bridge noise and rail noise is investigated. Generally, the rail noise is dominant above the bridge, and the bridge noise has a larger contribution to the total noise beneath the bridge. The rail noise from the U-shaped girder is much smaller than that from the box girder due to the shielding effect of the webs.

Dynamics of an impinging jet. Part 2. The noise generation

1982 ◽  
Vol 116 ◽  
pp. 379-391 ◽  
Author(s):  
Nagy S. Nosseir ◽  
Chih-Ming Ho
Keyword(s):  
Coherent Structures ◽  
Near Field ◽  
Pressure Fluctuations ◽  
Aerodynamic Noise ◽  
Far Field ◽  
Noise Generation ◽  
Physical Mechanisms ◽  
Field Noise ◽  
Subsonic Jet ◽  
Jet Axis

The aerodynamic noise generated by a subsonic jet impinging on a flat plate is studied from measurements of near-field and surface-pressure fluctuations. The far-field noise measured at 90° to the jet axis is found to be generated by two different physical mechanisms. One mechanism is the impinging of the large coherent structures on the plate, and the other is associated with the initial instability of the shear layer. These two sources of noise radiate to the far field via different acoustical paths.

scholarly journals Heat transfer analysis of double tube heat exchanger with wavy inner tube

2021 ◽  
pp. 266-266
Author(s):  
Ceren Hasgül ◽  
Gülşah Çakmak
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heat Transfer Analysis ◽  
Wave Number ◽  
Straight Tube ◽  
Flow Conditions ◽  
Ansys Fluent ◽  
Tube Heat Exchanger

In this study, the effect of the design on the heat transfer is numerically investigated by using the "wavy inner tube" in a double-pipe heat exchanger. A wavy inner tube was used in the design to give a turbulent effect to the fluid along the inner tube of a double tube heat exchanger. In numerical study, ANSYS 12.0 Fluent code program was used, and the basic protection equations were solved for steady-state, three-dimensional and turbulent flow conditions. The study was examined at Reynolds numbers ranging from 2700 to 5300. The obtained results were compared with the experimental data performed under the same conditions. As a result of this comparison, after it was seen that the results obtained from the numerical analysis and the experimental results were compatible with each other, the wave number of the inner tube was increased and analyzed with the ANSYS fluent code program. When the data obtained as a result of the analyzes were evaluated, it was seen that the highest heat transfer was obtained from the 16 wave tube heat exchanger, which has the highest number of waves and under counter flow conditions. The increase in heat transfer increased by 270% compared to the straight tube.

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