Acoustic excitation of stationary streamwise structures in a separation region on a straight wing

2005 ◽  
Vol 17 (7) ◽  
pp. 078107 ◽  
Author(s):  
A. P. Brylyakov ◽  
B. Yu. Zanin ◽  
V. N. Kovrizhina ◽  
G. M. Zharkova
Keyword(s):  
Acoustic Excitation ◽  
Separation Region ◽  
Streamwise Structures ◽  
Straight Wing

Cross-Wire Measurements in the Wake of an Airfoil at Low Reynolds Numbers With and Without Acoustic Excitation

2002 ◽  
Author(s):  
Serhiy Yarusevych ◽  
Pierre E. Sullivan ◽  
John G. Kawall
Keyword(s):  
Vortex Shedding ◽  
Reynolds Numbers ◽  
Surface Flow ◽  
Wake Vortex ◽  
Acoustic Excitation ◽  
Separation Region ◽  
Wind Tunnel Experiments ◽  
Wake Structure ◽  
Low Reynolds Numbers ◽  
Cross Wire

The wake structure and vortex shedding characteristics of a NACA 0025 airfoil were studied experimentally. Wind tunnel experiments were carried out for three Reynolds numbers and three angles of attack by means of cross-wire measurements, spectral analysis and complementary surface flow visualization. Evidence of wake vortex shedding and flow separation was obtained for most of the cases examined, and dependence of these phenomena on Reynolds number and angle of attack was found. External acoustic excitation at a particular frequency was found to eliminate or reduce the separation region and decrease the airfoil wake. Moreover, the results show that the acoustic excitation has a significant effect on vortex shedding and can improve airfoil performance, i.e. produce an increase of the lift and/or decrease of the drag.

scholarly journals The Characteristics of Debye Effect Magnetic Field Under Acoustic Excitation

2021 ◽  
Vol 1885 (4) ◽  
pp. 042021
Author(s):  
Yujing Xu ◽  
Mengchun Pan ◽  
Qi Zhang ◽  
Dixiang Chen ◽  
Zhongyan Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Acoustic Excitation

scholarly journals Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Three Dimensional ◽  
High Growth ◽  
Aerodynamic Characteristics ◽  
Inlet Guide Vane ◽  
Separation Region ◽  
Clearance Flow ◽  
New Type ◽  
Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

scholarly journals Vibration responses of a satellite subjected to acoustic excitation at launch stage

2021 ◽  
Vol 1786 (1) ◽  
pp. 012034
Author(s):  
Jie Zhang ◽  
Weihua Xie ◽  
Jiacong Yin ◽  
liu Huiliang ◽  
Jiang Zhou
Keyword(s):  
Acoustic Excitation ◽  
Vibration Responses

Effect of a conical separation region on cold gas-dynamic spraying

2012 ◽  
Vol 53 (6) ◽  
pp. 948-953 ◽  
Author(s):  
A. P. Alkhimov ◽  
V. F. Kosarev ◽  
S. V. Klinkov ◽  
A. A. Sova
Keyword(s):  
Cold Gas Dynamic Spraying ◽  
Separation Region ◽  
Gas Dynamic ◽  
Cold Gas

Effects of Acoustic Excitation on a Swirling Diffusion Flame

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Michael E. Loretero ◽  
Rong F. Huang
Keyword(s):  
Flow Field ◽  
Bluff Body ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Mie Scattering ◽  
Flame Length ◽  
Laser Doppler Velocimeter ◽  
Scattering Method ◽  
Acoustic Excitation ◽  
Characteristic Modes

A swirling double concentric jet is commonly used for nonpremixed gas burner application for safety reasons and to improve the combustion performance. Fuel is generally spurted at the central jet while the annular coflowing air is swirled. They are normally separated by a blockage disk where the bluff-body effects further enhance the recirculation of hot gas at the reaction zone. This paper aims to experimentally investigate the behavior of flame and flow in a double concentric jet combustor when the fuel supply is acoustically driven. Laser-light sheet assisted Mie scattering method has been used to visualize the flow, while the flame lengths were measured by a conventional photography technique. The fluctuating velocity at the jet exit was measured by a two-component laser Doppler velocimeter. Flammability and stability at first fuel tube resonant frequency are reported and discussed. The evolution of flame profile with excitation level is presented and discussed, together with the reduction in flame length. The flame in the unforced reacting axisymmetric wake is classified into three characteristic modes, which are weak swirling flame, lifted flame, and transitional reattached flame. These terms reflect their primary features of flame appearances, and when the acoustic excitation is applied, the flame behaviors change with the excitation frequency and amplitude. Four additional characteristic modes are identified; e.g., at low excitation amplitudes, wrinkling flame with a blue annular film is observed because the excitation induces vortices in the central fuel jet and hence gives rise to the wrinkling of flame. The central jet vortices become larger with the increase in excitation amplitude and thus lead to a wider and shorter flame. If the excitation amplitude is increased above a certain value, the central jet vortices change the rotation direction and pacing with the annular jet vortices. These changes in the flow field induce large turbulent intensity and mixing and therefore make the flame looks blue and short. Further increase in the excitation amplitude would lift the flame because the flow field would be dramatically modified.

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