Experimental Study of Tip-Gap Turbulent Flow Structure

2006 ◽  
Author(s):  
Genglin Tang ◽  
Roger L. Simpson ◽  
Qing Tian
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Flow Structure ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Normal Velocity ◽  
Compressor Cascade ◽  
Custom Made ◽  
Turbulent Flow Structure

Experimental results are presented from a study of the tip-gap turbulent flow structure in a low-speed linear compressor cascade wind tunnel at Virginia Tech by utilizing surface oil flow visualization, endwall pressure measurements, and instantaneous velocity measurements with a custom-made 3-orthogonal-velocity-component fiber-optic laser-Doppler velocimetry (LDV) system. Tip gap flows are pressure-driven and highly skewed three-dimensional turbulent flows. The crossflow velocity normal to the blade chord is nearly uniform in the mid tip gap and changes substantially from the pressure to suction side due to the local tip pressure loading while the TKE does not vary much across the mid tip gap. The tip gap flow correlations of streamwise and wall normal velocity fluctuations decrease significantly from the leading edge to the trailing edge of the blade due to flow skewing.

Turbulent Flow Structure and Swirl Number Effect in a Cyclone

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
X. W. Wang ◽  
Y. Zhou ◽  
W. O. Wong
Keyword(s):  
Turbulent Flow ◽  
Flow Structure ◽  
Three Dimensional ◽  
Careful Analysis ◽  
Cylindrical Chamber ◽  
Swirl Number ◽  
Turbulent Flow Structure ◽  
Mean And Variance ◽  
The Mean ◽  
Chamber Diameter

The turbulent flow within a cylinder‐on‐cone cyclone is highly three‐dimensional and our knowledge of this flow has yet to be improved. This work aims to improve our understanding of the flow structure, with special attention to the swirl number effect. The three velocity components of the flow were measured using LDA and PIV. The Reynolds number, based on the inlet velocity and the cyclone cylindrical chamber diameter, was 7.4 × 104, and the swirl number examined was from 2.4 to 5.3. Three regions of the flow have been identified after careful analysis of the data, which are referred to as the core, the outer and the wall‐affected regions, respectively; each is distinct from another in terms of the vorticity concentration, frequency of quasi‐periodical coherent structure, the probability density function, and mean and variance of velocities. It has been found that the flow, including its Strouhal numbers and radial distributions of the mean and fluctuating velocities, depends considerably on the swirl number.

scholarly journals Experimental Study on the Three Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part I — Velocity and Pressure Fields

1992 ◽  
Author(s):  
Shun Kang ◽  
Ch. Hirsch
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Horseshoe Vortex ◽  
Surface Flow ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Compressor Cascade ◽  
Tip Leakage Vortex ◽  
Tip Leakage

Experimental results from a study of the 3-D flow in a linear compressor cascade with stationary endwall at design conditions are presented for tip clearance levels of 1.0, 2.0 and 3.3 percent of chord, compared with the no clearance case. In addition to five-hole probe measurements, extensive surface flow visualizations are conducted. It is observed that for the smaller clearance cases a weak horseshoe vortex forms in the front of the blade leading edge. At all the tip gap cases, a multiple tip vortex structure with three discrete vortices around the midchord is found. The tip leakage vortex core is well defined after the midchord but does not cover a significantly great area in traverse planes. The presence of the tip leakage vortex results in the passage vortex moving close to the endwall and to the suction side.

Numerical Investigation of Passive Flow Control Using Wavy Blades in a Highly-Loaded Compressor Cascade

2018 ◽  
Author(s):  
Bo Wang ◽  
Yanhui Wu ◽  
Kai Liu
Keyword(s):  
Numerical Investigation ◽  
Flow Structure ◽  
Cross Flow ◽  
Leading Edge ◽  
Control Flow ◽  
Streamwise Vortices ◽  
Compressor Cascade ◽  
Control Effect ◽  
Suction Surface ◽  
Highly Loaded

Driven by the need to control flow separations in highly loaded compressors, a numerical investigation is carried out to study the control effect of wavy blades in a linear compressor cascade. Two types of wavy blades are studied with wavy blade-A having a sinusoidal leading edge, while wavy blade-B having pitchwise sinusoidal variation in the stacking line. The influence of wavy blades on the cascade performance is evaluated at incidences from −1° to +9°. For the wavy blade-A with suitable waviness parameters, the cascade diffusion capacity is enhanced accompanied by the loss reduction under high incidence conditions where 2D separation is the dominant flow structure on the suction surface of the unmodified blade. For well-designed wavy blade-B, the improvement of cascade performance is achieved under low incidence conditions where 3D corner separation is the dominant flow structure on the suction surface of the baseline blade. The influence of waviness parameters on the control effect is also discussed by comparing the performance of cascades with different wavy blade configurations. Detailed analysis of the predicted flow field shows that both the wavy blade-A and wavy blade-B have capacity to control flow separation in the cascade but their control mechanism are different. For wavy blade-A, the wavy leading edge results in the formation of counter-rotating streamwise vortices downstream of trough. These streamwise vortices can not only enhance momentum exchange between the outer flow and blade boundary layer, but also act as the suction surface fence to hamper the upwash of low momentum fluid driven by cross flow. For wavy blade-B, the wavy surface on the blade leads to a reduction of the cross flow upwash by influencing the spanwise distribution of the suction surface static pressure and guiding the upwash flow.

Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

2016 ◽  
Author(s):  
Wei Ma ◽  
Feng Gao ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
A. J. Wang
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

scholarly journals Turbulent flow structure at a 90-degree open channel confluence: Accounting for the distortion of the shear layer

2016 ◽  
Vol 12 ◽  
pp. 130-147 ◽  
Author(s):  
Saiyu Yuan ◽  
Hongwu Tang ◽  
Yang Xiao ◽  
Xuehan Qiu ◽  
Huiming Zhang ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Shear Layer ◽  
Flow Structure ◽  
Open Channel ◽  
Turbulent Flow Structure ◽  
Channel Confluence

Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology

2017 ◽  
Vol 122 (6) ◽  
pp. 1278-1293 ◽  
Author(s):  
Alexander N. Sukhodolov ◽  
Julian Krick ◽  
Tatiana A. Sukhodolova ◽  
Zhengyang Cheng ◽  
Bruce L. Rhoads ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Flow Structure ◽  
Channel Morphology ◽  
River Confluence ◽  
Turbulent Flow Structure
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