Investigation of Unsteady Characteristics of Vortex Breakdown

Unsteady Characteristics over Dynamic Delta Wings

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.128-129.350 ◽

2011 ◽

Vol 128-129 ◽

pp. 350-353

Author(s):

Ming Lu Zhang ◽

Yi Ren Yang ◽

Zhi Yong Lu

Keyword(s):

Wind Tunnel ◽

Vortex Breakdown ◽

Delta Wing ◽

Water Channel ◽

Spiral Wave ◽

Leading Edge ◽

Wave Frequency ◽

Delta Wings ◽

Static State ◽

Unsteady Characteristics

A study of flow and frequency characteristics of the leading-edge vortices over a delta wing undergoing pitching up-stop motions is presented. The experiments with the dynamic delta wings were conducted in a water channel and a wind tunnel respectively. Among them, the test of the flow visualization was completed in the water channel with the delta wing with pitching up-stop motions. The result shows that in the case of pitching up-stop movement the vortex breakdown position is dependent on the range of incidence at which the wing is subject to pitching up-stop and the reduced frequency k (k=c/2U∞). Analysis of the pressure signal measured in the wind tunnel shows when the delta wing is subject to pitching-up the nondimensional spiral wave frequency at nominal incidence in post-breakdown is higher than that at corresponding static state and the bigger the k is, the higher the nondimensional spiral wave frequency is. The same conclusion is fitted with different sweep delta wing.

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Unsteady Characteristics of Breakdown Vortices over Delta Wing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.66-68.1874 ◽

2011 ◽

Vol 66-68 ◽

pp. 1874-1877 ◽

Cited By ~ 1

Author(s):

Ming Lu Zhang ◽

Yi Ren Yang ◽

Zhi Yong Lu ◽

Li Lu

Keyword(s):

Wind Tunnel ◽

Vortex Flow ◽

Vortex Breakdown ◽

Delta Wing ◽

Pressure Fluctuations ◽

Spiral Wave ◽

Leading Edge ◽

Fluid State ◽

Unsteady Characteristics ◽

Leading Edge Vortices

Experiment of unsteady pressure measurement on the surface of wing with 75° sweep delta wing has been carried out in a wind tunnel in order to investigate unsteady characteristics of breakdown vortices over delta wing after the leading edge vortices were breakdown. The result of experiment shows that alter of RMS pressure fluctuations and fluid state of leading edge vortices on the top surface of delta wing are correlative. At the angle region with vortex breakdown, RMS of pressure fluctuations are very huge, similarly buffeting strength of delta wing are large. With increasing angle of attack, alter of buffeting strength is in accordance with RMS pressure fluctuations. Analysis of the pressure signal shows the spiral wave of the breakdown vortex flow over the wing is the primary part of whole RMS pressure fluctuations. Delta wing produces buffeting because of the spiral wave.

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