scholarly journals Performance of Combined Water Turbine with Semielliptic Section of the Savonius Rotor

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Kaprawi Sahim ◽  
Dyos Santoso ◽  
Agus Radentan
Keyword(s):  
Stream Flow ◽  
Free Stream ◽  
Irrigation Canal ◽  
Savonius Rotor ◽  
Important Variation ◽  
Turbine Performance ◽  
Water Turbine ◽  
Naca 0015 ◽  
Starting Torque ◽  
Suitable Power

The Darrieus turbine is a suitable power generation in free stream flow because it is simple in construction, but it has the disadvantage of its small starting torque. The Savonius turbine has a high starting torque but the efficiency is smaller than that of Darrieus turbine. To improve the starting torque of Darrieus turbine, the Savonius buckets are introduced into the Darrieus turbine and the combined turbine is called Darrieus-Savonius turbine. In this study, three semielliptic sections of aspect ratio 0.8 were used for Savonius bucket while the Darrieus blade used three wings of airfoil NACA 0015. The Darrieus-Savonius turbine’s performances were studied experimentally in an irrigation canal of South Sumatera, Indonesia. The results show that the distance of Savonius buckets from the shaft centre influences performance of combined turbine, and the attachment angle of Savonius rotor made important variation of turbine performance.

scholarly journals Experimental Study of Darrieus-Savonius Water Turbine with Deflector: Effect of Deflector on the Performance

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Kaprawi Sahim ◽  
Kadafi Ihtisan ◽  
Dyos Santoso ◽  
Riman Sipahutar
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Performance Characteristics ◽  
Power Coefficient ◽  
Irrigation Canal ◽  
Savonius Rotor ◽  
Water Turbine ◽  
Darrieus Rotor ◽  
Deflector Plate

The reverse force on the returning blade of a water turbine can be reduced by setting a deflector on the returning blade side of a rotor. The deflector configuration can also concentrate the flow which passes through the rotor so that the torque and the power of turbine can be considerably increased. The placing of Savonius in Darrieus rotor is carried out by setting the Savonius bucket in Darrieus rotor at the same axis. The combination of these rotors is also called a Darrieus-Savonius turbine. This rotor can improve torque of turbine. Experiments are conducted in an irrigation canal to find the performance characteristics of presence of deflector and Savonius rotor in Darrieus-Savonius turbine. Results conclude that the single deflector plate placed on returning blade side increases the torque and power coefficient. The presence of Savonius rotor increases the torque at a lower speed, but the power coefficient decreases. The torque and power coefficient characteristics depend on the aspect ratio of Savonius rotor.

Aspects of Shear Layer Unsteadiness in a Three-Dimensional Supersonic Wake

2005 ◽  
Vol 127 (6) ◽  
pp. 1085-1094 ◽  
Author(s):  
Alan L. Kastengren ◽  
J. Craig Dutton
Keyword(s):  
Shear Layer ◽  
Stream Flow ◽  
Free Stream ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Base Flow ◽  
Recirculation Region ◽  
Side View ◽  
Near Wake ◽  
Supersonic Wake

The near wake of a blunt-base cylinder at 10° angle-of-attack to a Mach 2.46 free-stream flow is visualized at several locations to study unsteady aspects of its structure. In both side-view and end-view images, the shear layer flapping grows monotonically as the shear layer develops, similar to the trends seen in a corresponding axisymmetric supersonic base flow. The interface convolution, a measure of the tortuousness of the shear layer, peaks for side-view and end-view images during recompression. The high convolution for a septum of fluid seen in the middle of the wake indicates that the septum actively entrains fluid from the recirculation region, which helps to explain the low base pressure for this wake compared to that for a corresponding axisymmetric wake.

scholarly journals Effect of wavelength of fish-like undulation of a hydrofoil in a free-stream flow

Sadhana ◽  
2017 ◽  
Vol 42 (4) ◽  
pp. 585-595 ◽  
Author(s):  
Thekkethil Namshad ◽  
Mukul Shrivastava ◽  
Amit Agrawal ◽  
Atul Sharma
Keyword(s):  
Stream Flow ◽  
Free Stream

A Note Related to the Pressure Inside an Inflating Parachute Canopy

1977 ◽  
Vol 28 (4) ◽  
pp. 271-277
Author(s):  
P R Payne ◽  
E G U Band
Keyword(s):  
Analytic Function ◽  
Stream Flow ◽  
Free Stream ◽  
Internal Flow ◽  
The Other ◽  
Virtual Mass ◽  
Ram Pressure ◽  
Parachute Canopy ◽  
Mass Terms ◽  
Internal Pressures

SummaryIf a canopy is idealised as a cylinder with one end open to the free-stream flow, and the other end closed, then the internal flow during inflation is given by a simple analytic function. In this note the function is derived and then the internal pressures and corresponding forces associated with inflation are determined. It is found that, in addition to ram pressure and the von Kármán “virtual mass” terms in the pressure equations, there are other transient terms associated with radial velocity and acceleration.

Investigation of vertical axis wind turbine airfoil performance in rain

2017 ◽  
Vol 232 (2) ◽  
pp. 181-194 ◽  
Author(s):  
Zhenlong Wu ◽  
Yihua Cao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Meteorological Condition ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance ◽  
Practical Design ◽  
Wind Turbine Airfoil ◽  
Naca 0015

Rainfall is a common meteorological condition that wind turbines may encounter and by which their performance may be affected. This paper comprehensively investigates the effects of rainfall on a NACA 0015 airfoil which is commonly used in vertical axis wind turbines. A CFD-based Eulerian–Lagrangian multiphase approach is proposed to study the static, rotating, and oscillating performances of the NACA 0015 airfoil in rainy conditions. It is found that for the different airfoil movements, the airfoil performance can seriously be deteriorated in the rain condition. Rain also causes premature boundary layer separations and more severe flow recirculations than in the dry condition. These findings seem to be the first open reports on rain effects on wind turbine performance and should be of some significance to practical design.

An Empirical Formula for Stagnation Point Velocity Gradient for Spheres and Circular Cylinders in Hypersonic Flow

1965 ◽  
Vol 69 (654) ◽  
pp. 407-408 ◽  
Author(s):  
D. R. Topham
Keyword(s):  
Stagnation Point ◽  
Velocity Gradient ◽  
Stream Flow ◽  
Free Stream ◽  
Circular Cylinders ◽  
Stream Velocity ◽  
Flow Properties ◽  
Transfer Rates ◽  
Point Velocity ◽  
Image Position

When stagnation heat transfer rates are expressed in terms of free stream flow properties, the following combination of terms is found to occur: —where ps pressure at the stagnation pointp∞free stream pressureU∞free stream velocityDnose diameterßstagnation point velocity gradient.

An Equation of State for Compressed Water from 1 to 1000 Bar and from 0°C tO 150°C

1968 ◽  
Vol 10 (4) ◽  
pp. 319-328 ◽  
Author(s):  
M. R. Gibson ◽  
E. A. Bruges
Keyword(s):  
Equation Of State ◽  
Thermodynamic Properties ◽  
Equations Of State ◽  
Dynamic Properties ◽  
Similar Type ◽  
Independent Variables ◽  
Turbine Performance ◽  
Dependent Variables ◽  
Water Turbine ◽  
Water Substance

The precision with which the thermodynamic properties of compressed water and steam are known has led, not unnaturally, to the development of equations of state suitable only for use on electronic digital computers. The equations are in the main empirical although some are highly sophisticated and lead to lengthy programs and complex sub-routines. Among such equations are those of the 1966 and 1967 Formulations of the Thermo-dynamic Properties of Ordinary Water Substance prepared by the International Formulation Committee of the International Steam Conference. The favoured form of equation has been one in which the dependent variables are enthalpy, volume and entropy and the independent variables pressure and temperature. However, this form of equation may not prove to be always the most suitable and the purpose of this paper is to describe how another type of equation, in which the dependent variable is enthalpy and the independent variables are pressure and entropy, may be established and applied. It is believed that this particular type of equation, relating as it does the three most important parameters in pump and turbine performance, has special qualities for design and efficiency calculations. By way of example the efficiency of a water turbine is evaluated according to the ‘thermodynamic method’ described by Thom (2). A concluding section outlines the further steps being taken by the authors to provide a similar type of equation over ranges of pressure and temperature up to 1000 bar and 1000°C.

Unified hydrodynamics study for various types of fishes-like undulating rigid hydrofoil in a free stream flow

2018 ◽  
Vol 30 (7) ◽  
pp. 077107 ◽  
Author(s):  
Namshad Thekkethil ◽  
Atul Sharma ◽  
Amit Agrawal
Keyword(s):  
Stream Flow ◽  
Free Stream

A Generalized Mathematical Model to Estimate Gas Turbine Starting Characteristics

1982 ◽  
Vol 104 (1) ◽  
pp. 194-201 ◽  
Author(s):  
R. K. Agrawal ◽  
M. Yunis
Keyword(s):  
Mathematical Model ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
System Combination ◽  
Turbine Performance ◽  
Start Up ◽  
Starting Characteristics ◽  
Starting Torque

The paper describes a generalized mathematical model to estimate gas turbine performance in the starting regime of the engine. These estimates are then used to calculate the minimum engine starting torque requirements, thereby defining the specifications for the aircraft starting system. Alternatively, the model can also be used to estimate the start up time at any ambient temperature or altitude for a given engine/aircraft starting system combination.

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