Experimental Study on Performance of Darrieus-Type Open Hydroturbine With Inlet Nozzle in Low Downstream Water Level Conditions

2011 ◽  
Author(s):  
Koutarou Hirowatari ◽  
Kai Shimokawa ◽  
Shunsuke Iwamoto ◽  
Kusuo Okuma ◽  
Satoshi Watanabe ◽  
...  
Keyword(s):  
Water Level ◽  
River Flow ◽  
Draft Tube ◽  
Cross Flow ◽  
Vertical Axis ◽  
Maximum Efficiency ◽  
Stable Operation ◽  
Lower Efficiency ◽  
Flow Type ◽  
Turbine Efficiency

A Darrieus-type open hydro turbine with inlet nozzle has been proposed for utilization of extra-low head hydropower though a ducted type is in general used, consisting of an intake, runner section and draft tube. The open turbine means the simplified one, which has no runner casing and no draft tube. By installing inlet nozzle for the open turbine, the turbine efficiency is never deteriorated in comparison with the ducted one. The role of inlet nozzle is to increase generated torque with higher efficiency on the upstream path of the Darrieus blade passing and to decrease the torque with lower efficiency on the other path by removing the runner casing as the Darrieus turbine is cross flow type. In the present paper, the more simplified open turbine, consisting of only the inlet nozzle and the quarter covered upper casing to support the runner shaft, is experimentally examined. It is found that the depth of water level, covering or uncovering the runner in downstream pond, which might be changed by flow rate in practical use due to river-flow type turbine, influences on the turbine performance. When the depth of water level is kept deeper than the runner height of vertical axis turbine, the performance is almost the same as that of the case with whole covered upper casing. With decreasing the water level shallower than the runner height, the generated power and the efficiency become deteriorated due to making the wavy motion of the water surface at first. Then the stable operation at the maximum efficiency point in normal condition cannot be obtained. The cause on the mechanism of performance deterioration is considered with visualization of fluid behavior around Darrieus blades.

An analysis of the impact of draft tube modifications on the performance of a Kaplan turbine by means of computational fluid dynamics

2017 ◽  
Vol 232 (11) ◽  
pp. 1937-1952
Author(s):  
Juergen Schiffer ◽  
Helmut Benigni ◽  
Helmut Jaberg
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Draft Tube ◽  
Vertical Axis ◽  
Hydropower Plant ◽  
Construction Costs ◽  
Turbine Efficiency ◽  
Kaplan Turbine ◽  
The Cost ◽  
The Impact

Due to the low electricity prices in central Europe, cost optimisations related to all parts of a new hydropower plant have become increasingly important. In case of a run-of-river hydropower plant using a vertical axis Kaplan turbine, one of the cost drivers are the excavation works. Thus, a decisive factor for the reduction of construction costs is the minimisation of the construction depth of the elbow-type draft tube. In course of the design phase of a new hydropower plant in Austria, an analysis of the impact of draft tube modifications on the performance of the Kaplan turbine was carried out by applying computational fluid dynamics. The net head of the turbine with a diameter of D = 3.15 m accounts for Hnet = 9.00 m and the maximum discharge per unit is Qmax = 57.5 m3/s. After it was proven that there is a good agreement of the numerically calculated and experimentally measured turbine efficiency for the original turbine configuration, various draft tube designs were tested in order to find out their impact on the turbine efficiency and to analyse the sources of draft tube losses in detail. Finally, it was possible to find a new draft tube design representing a compromise of reduced construction costs and acceptable turbine efficiency.

Unsteady Flow Analysis of the Vertical Axis Cross-Flow Wind Turbine

2006 ◽  
Author(s):  
E. Ejiri ◽  
S. Yabe ◽  
S. Hase ◽  
M. Ogiwara
Keyword(s):  
Wind Turbine ◽  
Flow Analysis ◽  
Cross Flow ◽  
Vertical Axis ◽  
Guide Vanes ◽  
Turbine Efficiency ◽  
Turbine Runner ◽  
Entire Flow ◽  
Improved Design ◽  
Turbine Design

Flow through the vertical axis cross-flow wind turbine was analyzed using computational fluid dynamics (CFD) to clarify current aerodynamic issues and to propose an improved design configuration for achieving better performance. The computed torque coefficients and power coefficients of a reference cross-flow wind turbine runner were compared with the experimental results. Flow around each blade of the turbine runner was then investigated based on the computed flow results. As a countermeasure to the issues found, a new wind turbine design was devised which has two guide vanes point-symmetrically arranged outside the turbine runner. It was experimentally shown that this improved design with the guide vanes increased turbine efficiency. However, performance predictions by CFD lack sufficient accuracy in the case of the turbine runner with the guide vanes, where complexity and unsteadiness prevail over the entire flow fields.

An Experimental Investigation of Cross-Flow Turbine Efficiency

1994 ◽  
Vol 116 (3) ◽  
pp. 545-550 ◽  
Author(s):  
Venkappayya R. Desai ◽  
Nadim M. Aziz
Keyword(s):  
Experimental Investigation ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Water Entry ◽  
Diameter Ratio ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Outer Diameter ◽  
Turbine Efficiency ◽  
The Cross

An experimental investigation was conducted to study the effect of some geometric parameters on the efficiency of the cross-flow turbine. Turbine models were constructed with three different numbers of blades, three different angles of water entry to the runner, and three different inner-to-outer diameter ratios. Nozzles were also constructed for the experiments to match the three different angles of water entry to the runner. A total of 27 runners were tested with the three nozzles. The results of the experiments clearly indicated that efficiency increased with increase in the number of blades. Moreover, it was determined that an increase in the angle of attack beyond 24 deg does not improve the maximum turbine efficiency. In addition, as a result of these experiments, it was determined that for a 24 deg angle of attack 0.68 was the most efficient inner-to-outer diameter ratio, whereas for higher angles of attack the maximum efficiency decreases with an increase in the diameter ratio from 0.60 to 0.75.

Performance Improvement of Cross-Flow Turbine with a Cylindrical Cavity and Guide Wall

2021 ◽  
Author(s):  
Naoto Ogawa ◽  
Mirei Goto ◽  
Shouichiro Iio ◽  
Takaya Kitahora ◽  
Young-Do Choi ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Performance Test ◽  
Guide Vane ◽  
Cross Flow ◽  
Maximum Efficiency ◽  
Small Hydropower ◽  
Turbine Efficiency ◽  
Partial Load ◽  
Guide Wall ◽  
The Cross

Abstract The cross-flow turbine has been utilizing the development of small hydropower less than about 500kW in the world. The turbine cost is lower than the other turbines because of its smaller assembled parts and more straightforward structures. However, the maximum efficiency of the cross-flow turbine is lower than that of traditional turbines. Improving the turbine efficiency without increasing manufacturing costs is the best way to develop small hydropower in the future. This study is aiming to improve the turbine efficiency at the design point and partial load. The runner's outflow angle varies with turbine speed and guide vane opening in the typical cross-flow turbine. The tangential velocity component remains in the outflow in these conditions; thus, change the outflow direction along the runner's radial direction is helpful for performance improvement. The authors experimentally change the desirable outflow angle by attaching a cavity and a guide wall at the outside casing tip. The turbine performance test was conducted for various turbine speeds and guide vane opening. Next, flow visualization around the runner was performed. As a result, the effect of the cavity and the guide wall can be revealed. The outlet flow fields are different by attaching the cavity and the guide wall, especially between the partial and optimum load conditions.

301 Power up approach by setting a new guide vanes for a vertical axis cross flow type of wind turbine

2005 ◽  
Vol 2005.44 (0) ◽  
pp. 80-81
Author(s):  
Kouki Kishinami ◽  
Jyunn Suzuki ◽  
Himsar Ambarita ◽  
Norihei Kon ◽  
Syouji Oono ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Cross Flow ◽  
Vertical Axis ◽  
Guide Vanes ◽  
Flow Type

Limits of the Turbine Efficiency for Free Fluid Flow

2001 ◽  
Vol 123 (4) ◽  
pp. 311-317 ◽  
Author(s):  
Alexander N. Gorban’ ◽  
Alexander M. Gorlov ◽  
Valentin M. Silantyev
Keyword(s):  
Wind Power ◽  
Three Dimensional ◽  
Cross Flow ◽  
Free Water ◽  
Accurate Estimate ◽  
Maximum Efficiency ◽  
Free Fluid ◽  
Two Dimensional ◽  
Turbine Efficiency ◽  
Tidal Streams

An accurate estimate of the theoretical power limit of turbines in free fluid flows is important because of growing interest in the development of wind power and zero-head water power resources. The latter includes the huge kinetic energy of ocean currents, tidal streams, and rivers without dams. Knowledge of turbine efficiency limits helps to optimize design of hydro and wind power farms. An explicitly solvable new mathematical model for estimating the maximum efficiency of turbines in a free (nonducted) fluid is presented. This result can be used for hydropower turbines where construction of dams is impossible (in oceans) or undesirable (in rivers), as well as for wind power farms. The model deals with a finite two-dimensional, partially penetrable plate in an incompressible fluid. It is nearly ideal for two-dimensional propellers and less suitable for three-dimensional cross-flow Darrieus and helical turbines. The most interesting finding of our analysis is that the maximum efficiency of the plane propeller is about 30 percent for free fluids. This is in a sharp contrast to the 60 percent given by the Betz limit, commonly used now for decades. It is shown that the Betz overestimate results from neglecting the curvature of the fluid streams. We also show that the three-dimensional helical turbine is more efficient than the two-dimensional propeller, at least in water applications. Moreover, well-documented tests have shown that the helical turbine has an efficiency of 35 percent, making it preferable for use in free water currents.

scholarly journals Concept design and numerical analysis of hybrid solar–wind turbine

2021 ◽  
Vol 850 (1) ◽  
pp. 012032
Author(s):  
K S Ackshaya Varshini ◽  
Alenkar K Aswin ◽  
H Rajan ◽  
K S Maanav Charan
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Mechanical Energy ◽  
Vertical Axis ◽  
Horizontal Axis ◽  
Maximum Efficiency ◽  
Concept Design ◽  
Lower Efficiency ◽  
Axis Orientation

Abstract A wind turbine is a device that converts wind energy to electrical energy. External factors such as wind speed and direction shift, as well as turbine blade design considerations, cause a significant amount of energy to be wasted throughout the conversion process. Considering all these losses, a turbine’s average efficiency is roughly 45 percent. The blades of a wind turbine are one of the most crucial factors in determining the turbine’s efficiency. The design and geometry of the blades have a direct impact on performance since it determines how much kinetic energy from the wind is converted into mechanical energy. Many concepts and technologies are being used to improve the efficiency of wind turbines while lowering their maintenance costs. Wind turbines based on their axis orientation are classified as vertical axis and horizontal axis. Vertical axis wind turbines are not as widespread as their horizontal-axis counterparts due to their lower efficiency. In this study, we will use a Savonius vertical axis wind turbine to investigate a way of enhancing its efficiency by installing solar panels on its vertical blades and determining the best performance angle at which the turbine should be kept achieving maximum efficiency. Computation fluid dynamic analysis and thermal and structural analysis has been performed to check the efficiency of the designed blade. As a result, an optimized wind turbine design has been developed.

scholarly journals Passive flow control mechanisms with bioinspired flexible blades in cross-flow tidal turbines

2021 ◽  
Vol 62 (5) ◽  
Author(s):  
Stefan Hoerner ◽  
Shokoofeh Abbaszadeh ◽  
Olivier Cleynen ◽  
Cyrille Bonamy ◽  
Thierry Maître ◽  
...  
Keyword(s):  
Turbine Blades ◽  
Cross Flow ◽  
Tidal Energy ◽  
Control Mechanisms ◽  
Passive Flow Control ◽  
Turbine Efficiency ◽  
Tidal Turbines ◽  
Passive Flow ◽  
Axial Turbines ◽  
The Cost

Abstract State-of-the-art technologies for wind and tidal energy exploitation focus mostly on axial turbines. However, cross-flow hydrokinetic tidal turbines possess interesting features, such as higher area-based power density in array installations and shallow water, as well as a generally simpler design. Up to now, the highly unsteady flow conditions and cyclic blade stall have hindered deployment at large scales because of the resulting low single-turbine efficiency and fatigue failure challenges. Concepts exist which overcome these drawbacks by actively controlling the flow, at the cost of increased mechatronical complexity. Here, we propose a bioinspired approach with hyperflexible turbine blades. The rotor naturally adapts to the flow through deformation, reducing flow separation and stall in a passive manner. This results in higher efficiency and increased turbine lifetime through decreased structural loads, without compromising on the simplicity of the design. Graphic abstract

Standardization of Cross Flow Turbine Design for Typical Micro-Hydro Site Conditions in Pakistan

2014 ◽  
Author(s):  
J. A. Chattha ◽  
M. S. Khan ◽  
H. Iftekhar ◽  
S. Shahid
Keyword(s):  
Electrical Power ◽  
Cross Flow ◽  
Power Production ◽  
Radius Of Curvature ◽  
Manufacturing Cost ◽  
Site Conditions ◽  
Hydro Power ◽  
Turbine Efficiency ◽  
Turbine Design ◽  
Typical Site

Pakistan has a hydro potential of approximately 42,000MW; however only 7,000MW is being utilized for electrical power production [1, 2]. Out of 42,000 MW, micro hydro potential is about 1,300MW [1, 2]. For typical site conditions (available flow rate and head) in Pakistan, Cross Flow Turbines (CFTs) are best suited for medium head 5–150m [3] for micro-hydro power production. The design of CFT generally includes details of; the diameter of the CFT runner, number of blades, radius of curvature and diameter ratio. This paper discusses the design of various CFTs for typical Pakistan site conditions in order to standardize the design of CFTs based on efficiency that is best suited for a given site conditions. The turbine efficiency as a function of specific speed will provide a guide for cross flow turbine selection based on standardized turbine for manufacturing purposes. Standardization of CFT design will not only facilitate manufacturing of CFT based on the available site conditions with high turbine efficiency but also result in reduced manufacturing cost.

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