Leading-Edge Separation Control by Means of Pulsed Vortex Generator Jets

AIAA Journal ◽  
2008 ◽  
Vol 46 (4) ◽  
pp. 837-846 ◽  
Author(s):  
Peter Scholz ◽  
Marcus Casper ◽  
Jens Ortmanns ◽  
Christian J. Kähler ◽  
Rolf Radespiel
Keyword(s):  
Vortex Generator ◽  
Leading Edge ◽  
Separation Control ◽  
Vortex Generator Jets ◽  
Edge Separation

Reducing Low-Pressure Turbine Stage Blade Count Using Vortex Generator Jet Separation Control

2002 ◽  
Author(s):  
Rolf Sondergaard ◽  
Jeffrey P. Bons ◽  
Matthew Sucher ◽  
Richard B. Rivir
Keyword(s):  
Boundary Layer ◽  
Vortex Generator ◽  
Separation Control ◽  
Surface Boundary ◽  
Freestream Turbulence ◽  
Skew Angle ◽  
Suction Surface ◽  
Simple Boundary ◽  
Design Value ◽  
Vortex Generator Jets

An experimental investigation has been conducted into the feasibility of increasing blade spacing (pitch) at constant chord in a linear turbine cascade. Vortex generator jets (VGJs) located on the suction surface of each blade in the cascade are employed to maintain attached boundary layers despite the increasing tendency to separate due to the increased uncovered turning. Tests were performed at low Mach numbers and at blade Reynolds numbers between 25,000 and 75,000 (based on axial chord and inlet velocity). The vortex generator jets (30 degree injection angle and 90 degree skew angle) were operated with steady flow with momentum blowing ratios between zero and five, and from two spanwise rows of holes located at 45% and 63% axial chord. In the absence of control, pitch-averaged wake losses increase up to 600% as the blade pitch is increased from its design value to twice the design value. With the application of VGJs, these losses were driven down to or below the losses at the design pitch. The effectiveness of VGJs was found to increase modestly with increasing Reynolds number up to the highest value tested, Re = 75,000. The fluid phenomenon responsible for this remarkable range of effectiveness is clearly more than a simple boundary layer transition effect, as boundary layer trips installed on the same blades without VGJ blowing had no beneficial effect on blade losses. Also, tests conducted at elevated levels of freestream turbulence (4% at the cascade inlet) where the suction surface boundary layer is generally turbulent, showed wake loss reduction comparable to tests conducted at the nominal 1% freestream turbulence. For all configurations, blowing from the upstream row had the greatest wake influence. These findings open the possibility that future LPT designs could take advantage of active separation control using integrated VGJs to reduce the turbine part count and stage weight without significant increase in pressure losses.

Study on Flow Separation Control by Vortex Generator Jets with Different Parameters

2012 ◽  
Vol 588-589 ◽  
pp. 1786-1789
Author(s):  
Yong Hui Xie ◽  
Zhong Yang Shen ◽  
Tao Fan
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Vortex Generator ◽  
Separation Control ◽  
Flow Separation Control ◽  
Profound Influence ◽  
Orthogonal Analysis ◽  
Conical Diffuser ◽  
Flow Charts ◽  
Vortex Generator Jets

In order to investigate the mechanism of flow separation control in conical diffuser by vortex generator jets (VGJs) method, numerical simulations were conducted to discuss the effect of VGJs with different parameters on flow control. The aerodynamic performance in conical diffuser with angle of 14° was tested and analyzed based on Shear-Stress-Transport (SST) simulation. The flow charts at several sections were analyzed, illuminating the formation of complex vortices. Moreover, the effects of 5 VGJs parameters on the diffuser were analyzed by orthogonal analysis. It was shown that the number of jets and the pitch angle of jet showed more profound influence on the flow control by VGJs.

Experimental Study of Separation Control Over a Wide Range of Reynolds Numbers Using Dielectric Barrier Discharge Plasma Actuator on Airfoil

2017 ◽  
Author(s):  
Satoshi Sekimoto ◽  
Kozo Fujii ◽  
Masayuki Anyoji ◽  
Yuma Miyakawa ◽  
Shinichiro Ito ◽  
...  
Keyword(s):  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Plasma Actuator ◽  
Chord Length ◽  
Separation Control ◽  
Dielectric Barrier ◽  
Wide Range ◽  
Edge Separation

This study proposes separation control investigation using a Dielectric Barrier Discharge (DBD) plasma actuator on a NACA0015 airfoil over a wide range of Reynolds numbers. The airfoil was a two dimensional NACA0015 wing model with chord length of 200mm. Reynolds numbers based on the chord length were ranged from 252,000 to 1,008,000. A plasma actuator was installed at the leading edge and driven with AC voltage. Burst mode (duty cycle) actuations, in which nondimensional burst frequency F+ was ranged in 0.1–30, were applied. Time-averaged pressure measurements were conducted with angles of attack from 14deg to 22deg. The results show that initial flow fields without an actuation can be classified into three types; 1) leading edge separation, 2) trailing edge separation, and 3) hysteresis condition between 1) and 2), and the effect of burst actuation is different for each above initial condition.

scholarly journals A Separation Control of the Diffuser Flow by the Vortex Generator Jets

2004 ◽  
Vol 70 (696) ◽  
pp. 2012-2017
Author(s):  
Masashi HIGASHIURA ◽  
Hidetoshi AOKI ◽  
Tadashi MORIOKA ◽  
Shinji HONAMI
Keyword(s):  
Vortex Generator ◽  
Separation Control ◽  
Diffuser Flow ◽  
Vortex Generator Jets

scholarly journals Separation Control in a Conical Diffuser by Vortex Generator Jets

1997 ◽  
Vol 63 (605) ◽  
pp. 82-87
Author(s):  
Michihiro NISHI ◽  
Yasuhiro SHIBATA ◽  
Minoru OKAMOTO ◽  
Masayoshi NAKAMURA
Keyword(s):  
Vortex Generator ◽  
Separation Control ◽  
Conical Diffuser ◽  
Vortex Generator Jets
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