Performance of S1210 Profile Used in Current Turbine Blades With Tubes Inserted at a Regular Interval

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Parikshit Kundu ◽  
Arunjyoti Sarkar ◽  
Vishwanath Nagarajan
Keyword(s):  
Flow Separation ◽  
Turbine Blades ◽  
Leading Edge ◽  
Suction Side ◽  
Current Speed ◽  
Separation Process ◽  
Hydrodynamic Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Current Turbine

Abstract The annual power output of a current turbine is affected by flow separation followed by the stall condition in an environment of varying current speed. Flow separation appears as the fluid in the boundary layer over the blade surface loses its kinetic energy. Delaying this separation process is essential to extract more power throughout the year considering the variation in the current speed. Several active and passive means are available in the literature today to achieve a delay in the flow separation process. Inserting tubes in an aero/hydrofoil at a constant spacing, connecting the fluid near the leading edge and a downstream location on the suction side is a novel approach that has been numerically investigated here. The baseline profile chosen here is S1210, which is used in the current turbine blades. The hydrodynamic performance of the profile with tubes has been compared with the baseline profile in terms of the force coefficients, lift to drag ratio, and stall angle. The maximum lift has been noticed to be increased by 18% and the stall is delayed by 2 deg (from 10 deg to 12 deg). The maximum lift to drag ratio is increased by 130% at 12 deg (beyond the stall of the baseline profile). The results show that the insertion of tubes can make the existing profile more efficient for the stated application.

Roughness Sensitivity Considerations for Thick Rotor Blade Airfoils

2003 ◽  
Vol 125 (4) ◽  
pp. 468-478 ◽  
Author(s):  
R. P. J. O. M. van Rooij ◽  
W. A. Timmer
Keyword(s):  
Turbine Blades ◽  
Leading Edge ◽  
Lower Surface ◽  
Vortex Generators ◽  
Wind Turbine Blades ◽  
High Lift ◽  
Edge Roughness ◽  
Proper Design ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In modern wind turbine blades, airfoils of more than 25% thickness can be found at mid-span and inboard locations. At mid-span, aerodynamic requirements dominate, demanding a high lift-to-drag ratio, moderate to high lift and low roughness sensitivity. Towards the root, structural requirements become more important. In this paper, the performance for the airfoil series DU FFA, S8xx, AH, Risø and NACA are reviewed. For the 25% and 30% thick airfoils, the best performing airfoils can be recognized by a restricted upper-surface thickness and an S-shaped lower surface for aft-loading. Differences in performance of the DU 91-W2-250 (25%), S814 (24%) and Risø-A1-24 (24%) airfoils are small. For a 30% thickness, the DU 97-W-300 meets the requirements best. Reduction of roughness sensitivity can be achieved both by proper design and by application of vortex generators on the upper surface of the airfoil. Maximum lift and lift-to-drag ratio are, in general, enhanced for the rough configuration when vortex generators are used. At inboard locations, 2-D wind tunnel tests do not represent the performance characteristics well because the influence of rotation is not included. The RFOIL code is believed to be capable of approximating the rotational effect. Results from this code indicate that rotational effects dramatically reduce roughness sensitivity effects at inboard locations. In particular, the change in lift characteristics in the case of leading edge roughness for the 35% and 40% thick DU airfoils, DU 00-W-350 and DU 00-W-401, respectively, is remarkable. As a result of the strong reduction of roughness sensitivity, the design for inboard airfoils can primarily focus on high lift and structural demands.

Numerical Investigation of Bionic Rudder With Leading-Edge Protuberances

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Hongtao Gao ◽  
Wencai Zhu
Keyword(s):  
Electron Microscopy ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Spanwise Direction ◽  
Flow Mechanism ◽  
Suction Surface ◽  
Edge Profile ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The duck's webbed feet are observed by using electron microscopy, and observations indicate that the edges of the webbed feet are the shape of protuberances. Therefore, the rudder with leading-edge protuberances is numerically studied in the present investigation. The rudder has a sinusoidal leading-edge profile along the spanwise direction. The hydrodynamic performance of rudder is analyzed under the influence of leading-edge protuberances. The present investigations are carried out at Re = 3.2 × 105 and 8 × 105. In the case of Re = 3.2 × 105, the curves of lift coefficient illustrate that the protuberant leading-edge scarcely affects the lift coefficient of bionic rudder. However, the drag coefficient of the bionic rudder is markedly lower than that of the unmodified rudder. Therefore, the lift-to-drag ratio of the bionic rudder is obviously higher than the unmodified rudder. In another case of Re = 8 × 105, the advantageous behavior of the bionic rudder with leading-edge protuberances is mainly performed in the post-stall regime. The flow mechanism of the significantly increased efficiency by the protuberant leading-edge is explored. It is obvious that the pairs of counter-rotating vortices are presented over the suction surface of bionic rudder, and therefore, the flow is more likely to adhere to the suction surface of bionic rudder.

Roughness Sensitivity Considerations for Thick Rotor Blade Airfoils

2003 ◽  
Author(s):  
R. P. J. O. M. van Rooij ◽  
W. A. Timmer
Keyword(s):  
Rotor Blade ◽  
Turbine Blades ◽  
Leading Edge ◽  
Lower Surface ◽  
Wind Turbine Blades ◽  
Strong Reduction ◽  
High Lift ◽  
Edge Roughness ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In modern wind turbine blades airfoils of more than 25% thickness can be found at mid-span and inboard locations. In particular at mid-span aerodynamic requirements dominate, demanding a high lift-to-drag ratio, moderate to high lift and low roughness sensitivity. Towards the root srtuctural requirements become more important. In this paper the performance for the airfoil series DU, FFA, S8xx, AH, Riso̸ and NACA are reviewed. For the 25% and 30% thick airfoils the best performing airfoils can be recognized by a restricted upper surface thickness and a S-shaped lower surface for aft-loading. Differences in performance of the DU 91-W2-250 (25%), S814 (24%) and Riso̸-A1-24 (24%) airfoil are small. For a 30% thickness the DU 97-W-300 meets the requirements best. At inboard locations the influence of rotation can be significant and 2d wind tunnel tests do not represent the characteristics well. The RFOIL code is believed to be capable of approximating the rotational effect. In particular the change in lift characteristics in the case of leading edge roughness for the 35% and 40% thick DU airfoils, respectively DU 00-W-350 and DU 00-W–401, is remarkable. Due to the strong reduction of roughness sensitivity the design for inboard airfoils could primarily focus on high lift and structural demands.

scholarly journals Numerical Investigation of Turbine Blades with Leading-Edge Tubercles in Uniform Current

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2205
Author(s):  
Shuling Chen ◽  
Yan Liu ◽  
Changzhi Han ◽  
Shiqiang Yan ◽  
Zhichao Hong
Keyword(s):  
Flow Separation ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Micro Scale ◽  
Drag Forces ◽  
Uniform Current ◽  
Naca0018 Airfoil ◽  
Lift And Drag

Inspired by the tubercles on humpback whale flippers, leading-edge tubercles have been incorporated into the design of wings and turbine blades in an attempt to improve their hydrodynamic performance. Although promising improvements, especially in terms of the stall performance, have been demonstrated in the limited research that exists to date, the effectiveness of the leading-edge tubercles seems to be influenced by the base blade. This paper focuses on the introduction of sinusoidal leading-edge tubercles to a base blade developed from the classic NACA0018 airfoil, and numerically investigates the effectiveness of leading-edge tubercles on the hydrodynamics associated with the blade in uniform current with different attack angles. Both the macroscopic parameters, such as the lift and drag forces, and the micro-scale flow characteristics, including the vortex and flow separation, are analyzed. The results indicate that the leading-edge tubercles brings a significant influence on the hydrodynamic forces acting on the blade when subjected to an attack angle greater than 15°. This study also reveals the important role of the turbulence and flow separation on hydrodynamic loading on the blade and the considerable influence of the tubercles on such micro-scale flow characteristics. Although the conditions applied in this work are relatively ideal (e.g., the blade is fixed in a uniform flow and the end effect is ignored), the satisfactory agreement between the numerical and corresponding experimental data implies that the results are acceptable. This work builds a good reference for our future work on the hydrodynamic performance of tidal turbines which adopt this kind of blade for operating in both uniform and shearing currents.

Cooling of Turbine Blades With Expanded Exit Holes: Computational Analyses of Leading Edge and Pressure-Side of a Turbine Blade

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Fariborz Forghan ◽  
Omid Askari ◽  
Uichiro Narusawa ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Leading Edge ◽  
Weak Shock ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Computational Analyses

Turbine blades are cooled by a jet flow from expanded exit holes (EEH) forming a low-temperature film over the blade surface. Subsequent to our report on the suction-side (low-pressure, high-speed region), computational analyses are performed to examine the cooling effectiveness of the flow from EEH located at the leading edge as well as at the pressure-side (high-pressure, low-speed region). Unlike the case of the suction-side, the flow through EEH on the pressure-side is either subsonic or transonic with a weak shock front. The cooling effectiveness, η (defined as the temperature difference between the hot gas and the blade surface as a fraction of that between the hot gas and the cooling jet), is higher than the suction-side along the surface near the exit of EEH. However, its magnitude declines sharply with an increase in the distance from EEH. Significant effects on the magnitude of η are observed and discussed in detail of (1) the coolant mass flow rate (0.001, 0.002, and 0.004 (kg/s)), (2) EEH configurations at the leading edge (vertical EEH at the stagnation point, 50 deg into the leading-edge suction-side, and 50 deg into the leading-edge pressure-side), (3) EEH configurations in the midregion of the pressure-side (90 deg (perpendicular to the mainstream flow), 30 deg EEH tilt toward upstream, and 30 deg tilt toward downstream), and (4) the inclination angle of EEH.

The effect of leading-edge droop on the performance of cavitating hydrofoil in an oscillating environment

2009 ◽  
Vol 223 (10) ◽  
pp. 2331-2339
Author(s):  
K Park ◽  
H Sun ◽  
S Lee
Keyword(s):  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Control Surface ◽  
Navier Stokes ◽  
Two Phase ◽  
Sheet Cavitation ◽  
Maximum Angle ◽  
Oscillating Motion ◽  
Drag Ratio ◽  
Cavitating Hydrofoil

The hydrodynamics of cavitating hydrofoil in oscillating motion are important in the aspect of the performance and hydro-elasticity of the control surface of the ship. The effect of leading-edge droop is numerically studied in the oscillating hydrofoil with cavitation. A two-phase incompressible Navier—Stokes solver is used to compute the cavitation flow. The hydrodynamic performance of the baseline hydrofoil is compared with that of the fixed droop and the variable droop hydrofoil. The droop models delay the separation behind the sheet cavitation near the maximum angle of attack. When the pitch goes down, the drooped models suppress the collapse of the sheet cavitation. Therefore, they result in the improved hydrodynamic performance against the baseline model through the oscillation cycle. Among the three hydrofoils, the variable droop showed the smallest change of the lift-to-drag ratio.

Effects of leading-edge bevel angle on the aerodynamic forces of a non-slender 50° delta wing

2005 ◽  
Vol 109 (1098) ◽  
pp. 403-407 ◽  
Author(s):  
J. J. Wang ◽  
S. F. Lu
Keyword(s):  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Relative Thickness ◽  
Aerodynamic Performances ◽  
Stall Angle ◽  
Drag Ratio ◽  
Low Speed Wind Tunnel ◽  
Lift To Drag Ratio ◽  
Blunt Leading Edge

Abstract The aerodynamic performances of a non-slender 50° delta wing with various leading-edge bevels were measured in a low speed wind tunnel. It is found that the delta wing with leading-edge bevelled leeward can improve the maximum lift coefficient and maximum lift to drag ratio, and the stall angle of the wing is also delayed. In comparison with the blunt leading-edge wing, the increment of maximum lift to drag ratio is 200%, 98% and 100% for the wings with relative thickness t/c = 2%, t/c = 6.7% and t/c = 10%, respectively.

scholarly journals Lift-to-Drag Ratio Improvement on a Supersonic Transport by Leading-Edge Flap at Transonic Regions

2004 ◽  
Vol 52 (601) ◽  
pp. 65-71
Author(s):  
Dong-Youn Kwak ◽  
Katsuhiro Miyata ◽  
Masayoshi Noguchi ◽  
Kenji Yoshida ◽  
Kenichi Rinoie
Keyword(s):  
Leading Edge ◽  
Supersonic Transport ◽  
Drag Ratio ◽  
Lift To Drag Ratio

scholarly journals Numerical Analysis of Wind Turbine Airfoil Aerodynamic Performance with Leading Edge Bump

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Majid Asli ◽  
Behnam Mashhadi Gholamali ◽  
Abolghasem Mesgarpour Tousi
Keyword(s):  
Wind Turbine ◽  
Control Method ◽  
Flow Behavior ◽  
Renewable Energy Sources ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Vortex Generator ◽  
Leading Edge ◽  
Suction Side ◽  
Aerodynamic Performance

Aerodynamic performance improvement of wind turbine blade is the key process to improve wind turbine performance in electricity generated and energy conversion in renewable energy sources concept. The flow behavior on wind turbine blades profile and the relevant phenomena like stall can be improved by some modifications. In the present paper, Humpback Whales flippers leading edge protuberances model as a novel passive stall control method was investigated on S809 as a thick airfoil. The airfoil was numerically analyzed by CFD method in Reynolds number of 106and aerodynamic coefficients in static angle of attacks were validated with the experimental data reported by Somers in NREL. Therefore, computational results for modified airfoil with sinusoidal wavy leading edge were presented. The results revealed that, at low angles of attacks before the stall region, lift coefficient decreases slightly rather than baseline model. However, the modified airfoil has a smooth stall trend while baseline airfoil lift coefficient decreases sharply due to the separation which occurred on suction side. According to the flow physics over the airfoils, leading edge bumps act as vortex generator so vortices containing high level of momentum make the flow remain attached to the surface of the airfoil at high angle of attack and prevent it from having a deep stall.

Optimum NURBS Curve Fitting for Geometry Parameterization of Gas Turbine Blades’ Sections: Part I — Evolutionary Optimization Techniques

2012 ◽  
Author(s):  
A. Safari ◽  
H. G. Lemu
Keyword(s):  
Gas Turbine ◽  
Curve Fitting ◽  
Error Function ◽  
Turbine Blades ◽  
Leading Edge ◽  
Suction Side ◽  
Evolutionary Optimization ◽  
Optimization Techniques ◽  
Advantages And Disadvantages ◽  
Geometry Parameterization

This paper presents two evolutionary optimization methods: Genetic Algorithm and Differential Evolution, aimed at optimizing the location of a set of NURBS control points that are used to calculate the NURBS points for leading edge, trailing edge, suction side and pressure side of an airfoil shape. The approach is illustrated on point cloud of several 2D sections of a typical gas turbine compressor blade, so that the results can be used for both reverse engineering purposes and geometry parameterization in airfoil aerodynamic shape optimization process. The optimization algorithms in this research are based on minimization of an analytical error function related to the distance between the fitted curve and original data points. Finally, the obtained results from these two techniques are compared with each other to distinguish the advantages and disadvantages of each method for such curve fitting problems.

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