Airfoil Blades

2019 ◽  
pp. 57-65
Author(s):  
Grady Koch ◽  
Elias Koch
Keyword(s):  
Airfoil Blades

Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 1: NACA 0012 and NACA 4415

2015 ◽  
Vol 787 ◽  
pp. 250-254 ◽  
Author(s):  
T. Micha Premkumar ◽  
Sivamani Seralathan ◽  
T. Mohan ◽  
N.N.P. Saran Reddy
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Static Pressure Distribution ◽  
Numerical Studies ◽  
Airfoil Blades ◽  
Torque Values ◽  
Naca 0012

This is Part-1 of the two-part paper in considering the effect of cambered airfoil blades on self-starting of vertical axis wind turbine. Part 1 reports the numerical studies on self-starting of vertical axis wind turbine with comparative studies involving NACA 0012 and cambered airfoil NACA 4415. Part 2 of the paper deals with numerical studies of NACA 0018 and cambered air foil NACA 63415. Darrieus type VAWT is attracting many researchers attention for its inherent advantages and its diversified applications. However, a disadvantage is when the rotor is stationary, no net rotational forces arises, even at high-wind speed. The principal advantage of the vertical axis format is their ability to accept wind from any direction without yawing mechanism. However, self-starting capability is the major drawbacks. Moreover, literatures based on computational analysis involving the cambered airfoil are few only. The objective of this present study is to select the suitable airfoil blades on self-starting of VAWT at low-Reynolds number. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. The commercial CFD code, ANSYS CFX 13.0© was used for the present studies. Initially, the flow over NACA 0012 was simulated and analyzed for different angles of attacks and similarly carried out for NACA 4415. The contours of static pressure distribution and velocity as well as the force and torque were obtained. Even though the lift force for cambered airfoil NACA 4415 is higher, based on the torque values of the above blade profiles, asymmetrical airfoil NACA 0012 is found to be appropriate for self-starring of VAWT.

scholarly journals Resonance Vibration of Mistuned Bladed Discs in Stationary Operations

1997 ◽  
Author(s):  
Romuald Rządkowski
Keyword(s):  
Numerical Model ◽  
Compressible Flow ◽  
Two Dimensional ◽  
Rotating System ◽  
Response Level ◽  
Stationary Response ◽  
The Real ◽  
Disc Model ◽  
Real Geometry ◽  
Airfoil Blades

A numerical model for the calculation of resonance stationary response of mistuned bladed disc is presented. The bladed disc model includes all important effects on a rotating system of the real geometry. The excitation forces were calculated by a code on the basis of two-dimensional compressible flow (to M < 0.8) for thin airfoil blades. The calculations presented in this paper show that centrifugal stress, and the values of excitation forces, play an important role in considering the influence of mistuning on the response level.

Porosity of Solid and Cored Turbine Blades of Aircraft Engines

2015 ◽  
Vol 226 ◽  
pp. 115-118
Author(s):  
Stanisław Roskosz ◽  
Jacek Nawrocki ◽  
Krzysztof Kubiak
Keyword(s):  
Turbine Blade ◽  
Turbine Blades ◽  
Aircraft Engines ◽  
Pouring Temperature ◽  
Porosity Level ◽  
Lower Porosity ◽  
Thin Walled ◽  
Airfoil Blades ◽  
Inconel 713C ◽  
Design And Manufacture

Paper presents results of quantitative evaluation of porosity conducted on big, thin walled airfoil turbine blades made from Inconel 713C alloy. To decrease mass, blades are design and manufacture like thin walled cored castings. Manufacturing of big thin walled casting airfoil blades is extremely difficult. During exploitation casting work undergo cycle fatigue. In that cause casting should be free of casting defects, including porosity. Conducted research focused on Inconel 713C superalloy pouring temperature effect on porosity level of cored casted turbine blade. Results were compared to porosity of solid casted turbine blade. It was found that porosity of cored blades is lower than solid blade porosity. In cored blades higher porosity is located on airfoil convex side. Airfoil concave side has lower porosity.

scholarly journals A Study on Developing Pico Propeller Turbine for Low Head Micro Hydropower Plants in Nepal

2014 ◽  
Vol 9 (1) ◽  
pp. 36-53 ◽  
Author(s):  
Pradhumna Adhikari ◽  
Umesh Budhathoki ◽  
Shiva Raj Timilsina ◽  
Saurav Manandhar ◽  
Tri Ratna Bajracharya
Keyword(s):  
Cross Flow ◽  
Design Flow ◽  
Constant Thickness ◽  
Manufacturing Cost ◽  
Scaling Effects ◽  
Speed Increase ◽  
Hilly Region ◽  
Low Head ◽  
High Head ◽  
Airfoil Blades

Most of the turbines used in Nepal are medium or high head turbines. These types of turbines are efficient but limited for rivers and streams in the mountain and hilly region which have considerably high head. Low head turbines should be used in the plain region if energy is to be extracted from the water sources there. This helps in the rural electrification and decentralized units in community, reducing the cost of construction of national grid and also to its dependency, in already aggravated crisis situation. There are good turbine designs for medium to high heads but traditional designs for heads under about 5m (i.e. cross flow turbine and waterwheel) are slow running, requiring substantial speed increase to drive an AC generator. Propeller turbines have a higher running speed but the airfoil blades are normally too complicated for micro hydro installations. Therefore, the open volute propeller turbine with constant thickness blades was ventured as possible solution. Such type of propeller turbine is designed to operate at low inlet head and high suction head. This enables the exclusion of closed spiral casing. Also, the constant thickness blades enable the use of forging process instead of casting of complex airfoil blades. This leads to considerable reduction in manufacturing cost and complexity. A 1kW prototype was designed and scale down model of 185W was fabricated and tested. The runner consisted of five blades of 4mm thickness with camber and twist. The runaway speed of 1058 rpm was attained at design flow rate of 25 l/s. At full load the efficiency of model was found to be about 57%. Applying scaling effects the expected efficiency of the prototype was estimated to be about 60%. DOI: http://dx.doi.org/10.3126/jie.v9i1.10669   Journal of the Institute of Engineering, Vol. 9, No. 1, pp. 36–53

Unsteady Aerodynamic Characteristics of Oscillating Cascade With Separation Bubble in High Subsonic Flow

2005 ◽  
Author(s):  
Toshinori Watanabe ◽  
Mizuho Aotsuka
Keyword(s):  
Subsonic Flow ◽  
Separation Bubble ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Influence Coefficient ◽  
Unsteady Aerodynamic ◽  
Key Factor ◽  
Influence Coefficient Method ◽  
Airfoil Blades ◽  
High Subsonic Flow

Unsteady aerodynamic characteristics of an oscillating cascade composed of DCA (Double Circular Arc airfoil) blades were studied both experimentally and numerically. The test cascade was operated in high subsonic flow fields with incidence angles up to 5 degrees. Above 3 degrees of the incidence, a separation bubble was produced at the leading edge. The principal concern of the present study was placed on the influence of the separated region on the vibration instability of the cascade blades. The experiment was conducted in a linear cascade wind tunnel in which seven DCA blades were equipped. The central one could be oscillated in a pitching mode. The influence coefficient method was adopted for the measurement, where the unsteady aerodynamic moments were measured on the central blade and neighboring ones. For the numerical analysis, a quasi 3-D N-S code with k–ε turbulence model was developed. The experimental and numerical results complemented each other to obtain detailed understanding of the unsteady aerodynamic behavior of the cascade. It was found that the separation bubble at the leading edge governed the vibration characteristics of blades through the oscillation of the separation bubble itself on the blade surfaces. From the results of parametric studies, the phase shift of the oscillation of the separation bubble was found to be a key factor for determining the unsteady aerodynamic characteristics of the oscillating blades.

Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 2: NACA 0018 and NACA 63415

2015 ◽  
Vol 787 ◽  
pp. 245-249 ◽  
Author(s):  
Sivamani Seralathan ◽  
T. Micha Premkumar ◽  
S. Thangavel ◽  
G.P. Pradeep
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Lift Force ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Numerical Studies ◽  
Airfoil Blades ◽  
Torque Values ◽  
Naca 0012

NACA 0012 and NACA 4415 were discussed in Part 1 of the paper to study the capabilities of the airfoil blades by considering the effect of cambered airfoil blade on self-starting of vertical axis wind turbine. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. In this Part 2 paper, detailed numerical results of asymmetrical NACA 0018 and cambered airfoil NACA 63415 are presented. The lift force generated and the rotor torque induced varies with angle of attack. Based on the contours of static pressure and velocity distribution as well as based on the torque induced in the flow field over blade profiles, NACA 0018 is found to be better compared to cambered airfoil. Even though the lift force for cambered airfoils are higher, based on the rotor torque values, the wind turbine with asymmetrical airfoil blades NACA 0012 is better by 9.80% compared with NACA 4415 and 21.73% compared with NACA 63415. Self-starting issue can be addressed by proper selection of NACA blade profiles. By comparing the four airfoil blades in Part 1 and Part 2 of the papers, the asymmetrical NACA 0012 is found to be most suitable airfoil for self-starting the vertical axis wind turbine (VAWT).

Mixing Efficiency Comparison of Symmetric and Asymmetric Airfoil Blades in a Continuous Stirred Tank Reactor

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Manosroi Woradej ◽  
Thongsanitkarn Jirayu ◽  
Ruangsak Parinya
Keyword(s):  
Biogas Production ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Stirred Tank ◽  
Mixing Efficiency ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank ◽  
Airfoil Blades

Abstract This study compared mixing efficiencies of the symmetric and asymmetric airfoil blades in a continuous stirred tank reactor (CSTR) at various mixing velocities and angles of attack. The symmetric airfoil blades (NACA0009 and NACA0015) and asymmetric airfoil blades (NACA2414 and NACA4412) were set at different angles of attack and mixing velocities. The tank reactor was equipped with two sets of three airfoil blades at the upper and the lower parts of the stirring shafts at the angles of attack 0 deg, 10 deg, 16 deg, and 20 deg, and the mixing velocities of 80, 110, 140, and 190 rpm. The mixing efficiencies were evaluated from the homogenous appearance of plastic particles (5 mm in diameter) dispersed in water by an image processing technique. The results indicated that the mixing efficiencies of both the symmetric and asymmetric airfoil blades increased with increasing mixing velocities and at the angles of attack 0 deg and 10 deg, and slightly decreased with increasing mixing velocities at the angles of attack 16 deg and 20 deg due to the blade stall and mixing saturation as well as short-circuiting flow from the high flowrate. There was no significant mixing velocity effect on mixing efficiencies at the angles of attack 10 deg, 16 deg, and 20 deg except 0 deg of the symmetric and asymmetric airfoil blade systems. The two asymmetric airfoil blade types gave higher mixing efficiencies than the two symmetric airfoil blade types. The results from this study can be applied for a novel blade design for an efficient mixing flow, which will be beneficial for industrial biogas production.

The Jet-Flap in Centrifugal Turbo Machines

1968 ◽  
Author(s):  
F. R. Goldschmied
Keyword(s):  
Aspect Ratio ◽  
Pressure Rise ◽  
Constant Speed ◽  
Centrifugal Impeller ◽  
Control Efficiency ◽  
Experimental Correlation ◽  
Airfoil Blades

Increased flow and pressure rise at constant speed have been achieved for a centrifugal impeller by application of the jet-flap and of mechanical tip flaps to backward-curved airfoil blades. Flow increments up to 16 percent and pressure increments up to 36 percent have been obtained with a control efficiency of 85 percent. Peak total-to-total efficiencies of the basic impeller have been found to be over 88 percent. An experimental correlation has been found for radial jet-flap cascades between lift increment and jet thrust, cascade solidity, jet angle, and effective blade aspect ratio.

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