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.

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.

scholarly journals Development of a Hydropower Turbine Using Seawater from a Fish Farm

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 266
Author(s):  
Md Rakibuzzaman ◽  
Sang-Ho Suh ◽  
Hyoung-Ho Kim ◽  
Youngtae Ryu ◽  
Kyung Yup Kim
Keyword(s):  
Power Plants ◽  
Guide Vane ◽  
Cross Flow ◽  
Synchronous Generator ◽  
Fish Farm ◽  
Hydropower Plant ◽  
Fish Farms ◽  
Data Simulation ◽  
Small Hydropower ◽  
Hydropower Plants

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

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.

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.

scholarly journals The Influence of Guide Vane to the Performance of Cross-Flow Wind Turbine on Waste Energy Harvesting System

2018 ◽  
Vol 159 ◽  
pp. 02014 ◽  
Author(s):  
Budi Santoso ◽  
Dominicus Danardono Dwi Prija Tjahjana
Keyword(s):  
Wind Turbine ◽  
Cooling Tower ◽  
Negative Impact ◽  
Guide Vane ◽  
Cross Flow ◽  
Waste Energy ◽  
Energy Harvesting System ◽  
The Cross ◽  
Tower Model ◽  
The Right

The purpose of this experiment is to know the influence of a single guide vane position and angle to the performance of a cross-flow wind turbine. The cross-flow wind turbine was positioned at the discharge outlet of a cooling tower model to harness the discharged wind for electricity generation. A guide vane was used to enhance the rotational speed of the turbines for power augmentation. Various position and angle of attack of the guide vane were tested in this experiment. To avoid negative impact on the performance of the cooling tower fan and to optimize the wind turbine performance, the turbine position on the discharge wind stream was also studied. The result showed that cross-flow wind turbine with a guide vane attached at the right position had a higher coefficient of power than cross flow turbine without guide vane. A crossflow wind turbine with the guide vane at the position of 150 mm from the center and 30° angles had the highest coefficient of power of 0.49. Comparing to the wind turbine without guide vane, the coefficient of power of the cross-flow wind turbine was increased about 84.3%.

scholarly journals Computational Analysis of a Double-Nozzle Crossflow Hydroturbine

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3380 ◽  
Author(s):  
Ram Adhikari ◽  
David Wood
Keyword(s):  
Power Output ◽  
Computational Analysis ◽  
The Other ◽  
Maximum Efficiency ◽  
Small Hydropower ◽  
Part Load ◽  
Turbine Efficiency ◽  
Numerical Studies ◽  
High Maximum ◽  
Flow Through

The crossflow turbines commonly used in small hydropower systems have a single nozzle. We are unaware of any studies of double-nozzle crossflow turbines which could have twice the power output of the single-nozzle design by doubling the flow through the same runner, with a high maximum efficiency. We present a computational analysis of a double-nozzle crossflow turbine, to determine the turbine efficiency and fundamental flow patterns. This work was based on a single-nozzle crossflow turbine with a maximum efficiency of 88%, one of the highest reported in the open literature through extensive experimental measurements. Previous numerical studies on this turbine have shown that the water flow in the runner was confined to less than half the runner periphery, implying that the other half could be used to double the runner power output by employing a second nozzle. We show that adding a second, identical nozzle without making any other changes to the design achieves a doubling of the power output. The dual-nozzle turbine, therefore, has the same efficiency as the original turbine. We also investigate the use of a slider to control the flow at part-load and show that part-load efficiency of the double-nozzle is very similar to that of the original turbine. This demonstrates the feasibility of using two nozzles for crossflow turbines.

Effect of operational modes on the removal of a synthetic organic chemical by powdered activated carbon during ultrafiltration

2001 ◽  
Vol 1 (5-6) ◽  
pp. 39-47
Author(s):  
Y. Matsui ◽  
A. Yuasa ◽  
F. Colas
Keyword(s):  
Activated Carbon ◽  
Cross Flow ◽  
Powdered Activated Carbon ◽  
Organic Chemical ◽  
Filtration Cycle ◽  
Dead End ◽  
Synthetic Organic Chemical ◽  
The Cross ◽  
Short Time ◽  
Operational Modes

The effects of operational modes on the removal of a synthetic organic chemical (SOC) in natural water by powdered activated carbon (PAC) during ultrafiltration (UF) were studied, through model simulations and experiments. The removal percentage of the trace SOC was independent of its influent concentration for a given PAC dose. The minimum PAC dosage required to achieve a desired effluent concentration could quickly be optimized from the C/C0 plot as a function of the PAC dosage. The cross-flow operation was not advantageous over the dead-end regarding the SOC removal. Added PAC was re-circulated as a suspension in the UF loop for only a short time even under the cross-flow velocity of gt; 1.0 m/s. The cross-flow condition did not contribute much to the suspending of PAC. The pulse PAC addition at the beginning of a filtration cycle resulted in somewhat better SOC removal than the continuous PAC addition. The increased NOM loading on PAC which was dosed in a pulse and stayed longer in the UF loop could possibly further decrease the adsorption rate.

Sign in / Sign up

Export Citation Format

Share Document