Prediction of the Cross-Flow Turbine Efficiency with Experimental Verification

2017 ◽  
Vol 143 (1) ◽  
pp. 04016075 ◽  
Author(s):  
Nuno H. C. Pereira ◽  
J. E. Borges
Keyword(s):  
Experimental Verification ◽  
Cross Flow ◽  
Turbine Efficiency ◽  
The Cross

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.

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.

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

Effects of alternating elliptical chamber on jet impingement heat transfer in vane leading edge under different cross-flow conditions

2021 ◽  
pp. 1-17
Author(s):  
K. Xiao ◽  
J. He ◽  
Z. Feng
Keyword(s):  
Heat Transfer ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leading Edge ◽  
Longitudinal Vortices ◽  
Impingement Jet ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Cross Flow Velocity ◽  
The Cross

ABSTRACT This paper proposes an alternating elliptical impingement chamber in the leading edge of a gas turbine to restrain the cross flow and enhance the heat transfer, and investigates the detailed flow and heat transfer characteristics. The chamber consists of straight sections and transition sections. Numerical simulations are performed by solving the three-dimensional (3D) steady Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) k– $\omega$ turbulence model. The influences of alternating the cross section on the impingement flow and heat transfer of the chamber are studied by comparison with a smooth semi-elliptical impingement chamber at a cross-flow Velocity Ratio (VR) of 0.2 and Temperature Ratio (TR) of 1.00 in the primary study. Then, the effects of the cross-flow VR and TR are further investigated. The results reveal that, in the semi-elliptical impingement chamber, the impingement jet is deflected by the cross flow and the heat transfer performance is degraded. However, in the alternating elliptical chamber, the cross flow is transformed to a pair of longitudinal vortices, and the flow direction at the centre of the cross section is parallel to the impingement jet, thus improving the jet penetration ability and enhancing the impingement heat transfer. In addition, the heat transfer in the semi-elliptical chamber degrades rapidly away from the stagnation region, while the longitudinal vortices enhance the heat transfer further, making the heat transfer coefficient distribution more uniform. The Nusselt number decreases with increase of VR and TR for both the semi-elliptical chamber and the alternating elliptical chamber. The alternating elliptical chamber enhances the heat transfer and moves the stagnation point up for all VR and TR, and the heat transfer enhancement is more obvious at high cross-flow velocity ratio.

scholarly journals Attenuation of Cross-Flow Fan Noise Using Porous Stabilizers

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Huanxin Lai ◽  
Meng Wang ◽  
Chuye Yun ◽  
Jin Yao
Keyword(s):  
Cross Flow ◽  
Sound Radiation ◽  
Internal Flow ◽  
Considerable Effect ◽  
Front Wall ◽  
Performance Curve ◽  
Fan Noise ◽  
Aerodynamic Performances ◽  
The Cross ◽  
Cross Flow Fan

This paper presents a qualitative analysis of controlling the cross-flow fan noise by using porous stabilizers. The stabilizer was originally a folded plate. It is changed into a porous structure which has a plenum chamber and vent holes on the front wall. In order to investigate the influences of using the porous stabilizers, experiments are carried out to measure the cross-flow fan aerodynamic performances and sound radiation. Meanwhile, the internal flow field of the fan is numerically simulated. The results show that the porous stabilizers have not produced considerable effect on the cross-flow fan's performance curve, but the noise radiated from the fan is strongly affected. This indicates the feasibility of controlling the cross-flow fan noise by using the porous stabilizers with selected porosity.

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