Effects of Splitter Plate Length on Aerodynamic Performance & Vortex Shedding on Flatback Airfoils

2012 ◽  
Author(s):  
Camille Metzinger ◽  
Jonathon Baker ◽  
Johannes Grobbel ◽  
Case (CP) Van Dam
Keyword(s):  
Vortex Shedding ◽  
Aerodynamic Performance ◽  
Splitter Plate ◽  
Plate Length

Wake Flow Behind a Cylinder With a Detached Splitter Plate

2005 ◽  
Author(s):  
Minter Cheng
Keyword(s):  
Strouhal Number ◽  
Vortex Shedding ◽  
Formation Process ◽  
Vortex Formation ◽  
Splitter Plate ◽  
Wake Flow ◽  
Plate Length ◽  
Splitter Plates ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

Fluid flow across a bluff body can induce a series alternating vortices in the downstream flow field. The vortex flow can produce adverse effects on many engineering applications. A number of studies have shown that the wake splitter plate is one of the means to stabilize the vortex formation process. However, most of the previous studies are confined to cylinders with attached splitter plates. Very few studies investigate the effects of the spacing between the cylinder and the splitter plate on the formation of wake vortices. In the present study, the effects of the splitter plate length as well as the gap distance between the splitter plate and the cylinder on the wake flow behind a cylinder have been studied experimentally for low Reynolds number of 400. Both circular and square cylinders are studied in this research. Four splitter plates with different length, 1 ≤ L/D ≤ 4, have been used and a range of cylinder and splitter plate gap distance, 0 < G/D < 6, have been studied. By using flow visualization technique and hot-film anemometer measurement, detailed measurements of the velocity distribution, the vortex shedding frequency, the wake width, and the wake formation length are carried out in order to get a clear understanding of the flow interference behavior. The experimental results indicate that splitter plates alter the vortex formation process in the wake causing a decrease in vortex shedding frequency. The Strouhal number decreases with increasing the splitter plate length as well as the gap distance between the cylinder and the splitter plate. It is shown that a jump in Strouhal number occurs at G/D of 3 to 6. The jump is splitter plate length dependent, and generally the gap distance at which jump takes place increases as the splitter plate length increases.

scholarly journals Flow Characteristics and Fluid Forces Reduction of Flow Past Two Tandem Cylinders in Presence of Attached Splitter Plate

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Ali Ahmed ◽  
Abdul Wahid ◽  
Raheela Manzoor ◽  
Noreen Nadeem ◽  
Naqib Ullah ◽  
...  
Keyword(s):  
Steady Flow ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Splitter Plate ◽  
Fluid Forces ◽  
Maximum Reduction ◽  
Plate Length ◽  
Tandem Cylinders ◽  
Flow Past ◽  
Spacing Ratio

Numerical simulations are carried out to study the flow around two tandem square cylinders (SC) under the effect of spacing ratio(g/D) and splitter plate length (l/D) for a fixed Reynolds number (Re) = 100. The g/D is varied from 0 to 10 and l/D is varied from 0.5 to 10. The splitter plate length is found to have strong effect on vortex shedding and fluid forces. The maximum reduction in mean drag coefficient is observed at l/D = 8, that is 15% and 78% for upstream and downstream cylinders, respectively. The maximum reduction in root-mean-square value of lift coefficient is found at l/D = 10, that is 99%. The flow pattern at both of these points is steady flow. There is 100% vortex shedding suppression for l/D > 5. The observed flow patterns for flow past tandem cylinders without splitter plate are; single bluff body (SBB), steady flow (SF), quasi-steady flow (QSF), fully developed flow (FDF) and fully developed two-row vortex street flow (FDTRVS) regimes. SBB, QSF and SF regimes were observed in presence of splitter plate.

Effect of Inclination Angle of Splitter Plate on Flow Over a Circular Cylinder

2011 ◽  
Author(s):  
Li Zhang ◽  
Lin Ding
Keyword(s):  
Circular Cylinder ◽  
Strouhal Number ◽  
Inclination Angle ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Splitter Plate ◽  
Plate Length ◽  
Pressure Distributions ◽  
Vortex Shedding Frequency

Two-dimensional unsteady laminar flow over a circular cylinder with an attached splitter plate was investigated numerically. To see the effect of the splitter plate length and inclination angle on the pressure distributions and vortex shedding, numerical simulations were done for moderate Reynolds numbers ranging from 100 to 500 in two different splitter plate lengths (1 and 2 diameters), and the angles between splitter plate and wake centerline was changed from 0 to 45 deg. Results indicate that the wake structure and length are dependent on the inclination angle of splitter plate. Near wake length is almost unchanged when θ>25 deg. On the other hand, circular cylinder’s drag coefficient is distinctly affected by the position of vortex. And significant local peaks of the RMS lift coefficient are obtained at θ=15 deg and 5 deg for L=1D and 2D respectively. The lift force is in one direction when the inclination angle is over a critical value. In addition, the non-dimensional Strouhal number representing the vortex shedding frequency characteristics varies as a function of the angle and has peak values at θ=20 and 5 deg for L=1D and 2D respectively. And the longer splitter plate causes more decrease in the Strouhal number for θ>15 deg.

Control of Vortex Shedding of Circular Cylinder in Shallow Water Flow Using an Attached Splitter Plate

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Huseyin Akilli ◽  
Cuma Karakus ◽  
Atakan Akar ◽  
Besir Sahin ◽  
N. Filiz Tumen
Keyword(s):  
Circular Cylinder ◽  
Shallow Water ◽  
Water Flow ◽  
Vortex Shedding ◽  
Flow Characteristics ◽  
Splitter Plate ◽  
Wake Flow ◽  
Flow Data ◽  
Shallow Water Flow ◽  
Plate Length

In the present work, passive control of vortex shedding behind a circular cylinder by splitter plates of various lengths attached on the cylinder base is experimentally investigated in shallow water flow. Detailed measurements of instantaneous and time-averaged flow data of wake flow region at a Reynolds number of Re=6300 were obtained by particle image velocimetry technique. The length of the splitter plate was varied from L∕D=0.2 to L∕D=2.4 in order to see the effect of the splitter plate length on the flow characteristics. Instantaneous and time-averaged flow data clearly indicate that the length of the splitter plate has a substantial effect on the flow characteristics. The flow characteristics in the wake region of the circular cylinder sharply change up to the splitter plate length of L∕D=1.0. Above this plate length, small changes occur in the flow characteristics.

Operational Risk Assessment of Wind Turbine Structures Using Probabilistic Analysis of Aerodynamically Induced Vibrations

2011 ◽  
Author(s):  
Antonio Velazquez ◽  
R. Andrew Swartz
Keyword(s):  
Risk Assessment ◽  
Wind Turbine ◽  
Numerical Solution ◽  
Vortex Shedding ◽  
Element Model ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Force Transmission ◽  
Resistance Risk ◽  
Structural Resistance

The study of efficiency and safety for wind turbine structures under variable operating conditions is increasingly important for wind turbine design. Optimum aerodynamic performance of a wind turbine demands that serviceability effects and ultimate strength loads remain under safety design limits. From the perspective of wind turbine efficiency, variations in wind speed causes bluffing effects and vortex shedding that lead to vibration intensities in the longitudinal and transversal direction that can negatively impact aerodynamic performance of the turbine. From the perspective of wind turbine safety, variations in loading may lead to transient internal loads that threaten the safety of the structure. Inertial effects and asynchronous delays on rotational-force transmission may generate similar hazards. Monitoring and controlling displacement limits and load demands at critical tower locations can improve the efficiency of wind power generation, not to mention the structural performance of the turbine from both a strength and serviceability point of view. In this study, a probabilistic monitoring approach is developed to measure the response of the combined tower/nacelle/blade system to stochastic loading, estimate peak demand, and compare that demand to building code-derived estimates of structural resistance. Risk assessment is performed for the effects of along and across-wind forces in a framework of quantitative risk analysis with the goal of developing a near real-time estimate of structural risk that may be used to monitor safety and serviceability of the structure as well as regulate the aggressiveness of the controller that commands the blade angle of attack. To accomplish this goal, a numerical simulation of the aerodynamic performance of a wind turbine (including blades, the nacelle and the tower) is analyzed to study the interaction between the structural system and incoming flow. A model based on distributed-stationary random wind load profile for the combined along-wind and across-wind responses is implemented in Matlab to simulate full aero-elastic dynamic analysis to simulate tower with nacelle, hub, rotor and tower substructures. Self-weight, rotational, and axial effects of the blades, as well as lateral resistance of substructure elements are incorporated in the finite element model, including vortex-shedding effects on the wake zone. Reliability on the numerical solution is inspected on the tower structure by comparing the numerical solution with established experimental-analytical procedures.

An Experimental Study on the Effect of Splitter Plate Angle on the VIV Behavior of Submarine Pipeline on an Erodible Bed Under Clear Water Condition

2013 ◽  
Author(s):  
Mohammad Javad Emamgholizadeh ◽  
Ahmad Reza Mostafa Gharabaghi ◽  
Karim Abedi ◽  
Mohammad Hossein Sedaaghi
Keyword(s):  
Vortex Shedding ◽  
Vibration Amplitude ◽  
Degrees Of Freedom ◽  
Oil And Gas ◽  
Processing Technique ◽  
Splitter Plate ◽  
Image Processing Technique ◽  
Contact Method ◽  
Hydrocarbon Reservoir ◽  
Scouring Depth

Pipeline is an appropriate method for transmission of oil and gas from seabed hydrocarbon reservoir to the land and platform or any other place where it is needed. Free spans in the line may occur initially by an uneven seabed or be created later due to under-scouring. Vortex Induced Vibration (VIV) may occur in these free spans at high Reynolds’ numbers. Resonance can occur if the frequency of vortex shedding is close to the pipeline’s natural frequency. Otherwise, it can cause pipeline’s fatigue leading to its breakage and consequently economical and environmental losses. In literature, different methods are presented for decreasing the scouring depth due to the vortex shedding. One of them is the application of splitter plate. In this paper, the effect of splitter plate’s angle with horizon (α) on the vibrating behavior of pipeline with two degrees of freedom over an erodible bed is studied experimentally. The experiments were performed for reduced velocity in the range of 2.45–5.06 and gap ratio of zero. Image processing technique as a non-contact method is used for measuring the vibrations of cylinder. Experimental results indicate that the splitter plate’s angle is an important factor on the cylinder’s vibration amplitude. According to these results, for the angle in the range of 0 ≤ α ≤ 30, the vibration amplitude is decreased while its frequency is increased, but the results are vice versa for the range of 60 ≤ α ≤ 90.

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