The Experts below are selected from a list of 67467 Experts worldwide ranked by ideXlab platform
Slamet Wahyudi - One of the best experts on this subject based on the ideXlab platform.
-
The Performance Characteristics of The Low Head Cross Flow Turbine Using Nozzle Roof Curvature Radius Centered on Shaft Axis
International Journal of Integrated Engineering, 2019Co-Authors: Djoko Sutikno, Rudy Soenoko, Sudjito Soeparman, Slamet WahyudiAbstract:The experimental study was intended to investigate performance characteristics of three cross Flow Turbine model using nozzle roof curvature radius centered on shaft axis designed on the same Flow rate, runner diameter and rotational speed which with each model having different runner width as well as its nozzle entry arc. The nozzle and runner width were designed as the fuction of the nozzle entry arc, the shorter pair of runner-nozzle the larger nozzle entry arc and vise versa. The nozzle entry arcs used in this experimental study were 75o, 90o and 120o. In addition, the three models having equal cross sectional area of nozzle entry. The three Turbine nozzles were designed having roof curvature radius centered on shaft axis. The such nozzle roof curvature were expected to be able to deliver water in the better direction as well as its Flow condition as the water entering the tubine runner. The experimental test rig consisted of the three Turbine models, pump, piping systems, magnetic Flow meter, and tachometer. The Flow rates, entered the Turbine, supplied by the pump were measured by the magnetic Flow meter. The power generated on the Turbine shaft was determined by measuring the torsion forces detected by using a spring balance, and Turbine speeds were detected by a hand held tachometer. The Turbine performance characteristics are shown by the relation of efficiency versus Flow rate, head, and specific speed; as well as the relation of efficiency versus velocity ratio and speed ratio. The velocity ratio was the ratio of runner pheripheral velocity to water jet velocity entering the runner; the speed ratio was the ratio of runner speed to water jet speed entering the runner. The results of the study indicate that best efficiency points increase as the nozzle entry arc decreases or on the other hand best effisiency points decrease as the nozzle entry arc increases. The results shows that the cross Flow Turbine using 75 and 90 degree entry arcs indicate efficiency and power higher than that of Turbine with 120 degree nozzle entry arc.
Sudjito Soeparman - One of the best experts on this subject based on the ideXlab platform.
-
The Performance Characteristics of The Low Head Cross Flow Turbine Using Nozzle Roof Curvature Radius Centered on Shaft Axis
International Journal of Integrated Engineering, 2019Co-Authors: Djoko Sutikno, Rudy Soenoko, Sudjito Soeparman, Slamet WahyudiAbstract:The experimental study was intended to investigate performance characteristics of three cross Flow Turbine model using nozzle roof curvature radius centered on shaft axis designed on the same Flow rate, runner diameter and rotational speed which with each model having different runner width as well as its nozzle entry arc. The nozzle and runner width were designed as the fuction of the nozzle entry arc, the shorter pair of runner-nozzle the larger nozzle entry arc and vise versa. The nozzle entry arcs used in this experimental study were 75o, 90o and 120o. In addition, the three models having equal cross sectional area of nozzle entry. The three Turbine nozzles were designed having roof curvature radius centered on shaft axis. The such nozzle roof curvature were expected to be able to deliver water in the better direction as well as its Flow condition as the water entering the tubine runner. The experimental test rig consisted of the three Turbine models, pump, piping systems, magnetic Flow meter, and tachometer. The Flow rates, entered the Turbine, supplied by the pump were measured by the magnetic Flow meter. The power generated on the Turbine shaft was determined by measuring the torsion forces detected by using a spring balance, and Turbine speeds were detected by a hand held tachometer. The Turbine performance characteristics are shown by the relation of efficiency versus Flow rate, head, and specific speed; as well as the relation of efficiency versus velocity ratio and speed ratio. The velocity ratio was the ratio of runner pheripheral velocity to water jet velocity entering the runner; the speed ratio was the ratio of runner speed to water jet speed entering the runner. The results of the study indicate that best efficiency points increase as the nozzle entry arc decreases or on the other hand best effisiency points decrease as the nozzle entry arc increases. The results shows that the cross Flow Turbine using 75 and 90 degree entry arcs indicate efficiency and power higher than that of Turbine with 120 degree nozzle entry arc.
-
optimization design of savonius diffuser blade with moving deflector for hydrokinetic cross Flow Turbine rotor
Energy Procedia, 2015Co-Authors: Bagus Wahyudi, Sudjito Soeparman, Hendrik Willem Marie HoeijmakersAbstract:The conventional Savonius Turbine is a good concept for small size wind-renewable energy systems; unfortunately always it has low efficiency. Inspired from the Savonius Blade, this research project designed the diffuser form as compartment between S blade and Tandem Blade of Savonius to produce “jet Flow” through narrow gap on the advancing blade in order to rotate more powerful the returning blade. The reason to change the air (wind) by using water as working fluid is to increase the body force (BF) which works on the blade due to increasing the density of fluid. The new model of Hydrokinetic Cross Flow Vertical Axis Turbine (CROSSVAT) is developed from Savonius S rotor with using Savonius Diffuser Blade (SDB) and moving deflector (guide blade). The function of SDB is to increase the velocity ratio on narrow gap (Rcv) also the drag force on surface of blades. Research method used the CFD simulation and Response Surface Method (RSM) to optimize the geometry of tandem blade and moving deflector (the moving guide blade). This study results two model CROSSVAT rotor using Tangential Deflector (model 1) and Radial Deflector (model 2).
Djoko Sutikno - One of the best experts on this subject based on the ideXlab platform.
-
The Performance Characteristics of The Low Head Cross Flow Turbine Using Nozzle Roof Curvature Radius Centered on Shaft Axis
International Journal of Integrated Engineering, 2019Co-Authors: Djoko Sutikno, Rudy Soenoko, Sudjito Soeparman, Slamet WahyudiAbstract:The experimental study was intended to investigate performance characteristics of three cross Flow Turbine model using nozzle roof curvature radius centered on shaft axis designed on the same Flow rate, runner diameter and rotational speed which with each model having different runner width as well as its nozzle entry arc. The nozzle and runner width were designed as the fuction of the nozzle entry arc, the shorter pair of runner-nozzle the larger nozzle entry arc and vise versa. The nozzle entry arcs used in this experimental study were 75o, 90o and 120o. In addition, the three models having equal cross sectional area of nozzle entry. The three Turbine nozzles were designed having roof curvature radius centered on shaft axis. The such nozzle roof curvature were expected to be able to deliver water in the better direction as well as its Flow condition as the water entering the tubine runner. The experimental test rig consisted of the three Turbine models, pump, piping systems, magnetic Flow meter, and tachometer. The Flow rates, entered the Turbine, supplied by the pump were measured by the magnetic Flow meter. The power generated on the Turbine shaft was determined by measuring the torsion forces detected by using a spring balance, and Turbine speeds were detected by a hand held tachometer. The Turbine performance characteristics are shown by the relation of efficiency versus Flow rate, head, and specific speed; as well as the relation of efficiency versus velocity ratio and speed ratio. The velocity ratio was the ratio of runner pheripheral velocity to water jet velocity entering the runner; the speed ratio was the ratio of runner speed to water jet speed entering the runner. The results of the study indicate that best efficiency points increase as the nozzle entry arc decreases or on the other hand best effisiency points decrease as the nozzle entry arc increases. The results shows that the cross Flow Turbine using 75 and 90 degree entry arcs indicate efficiency and power higher than that of Turbine with 120 degree nozzle entry arc.
Martin Wosnik - One of the best experts on this subject based on the ideXlab platform.
-
experimental study of a reference model vertical axis cross Flow Turbine
PLOS ONE, 2016Co-Authors: Peter Bachant, Martin Wosnik, Budi Gunawan, Vincent S NearyAbstract:The mechanical power, total rotor drag, and near-wake velocity of a 1:6 scale model (1.075 m diameter) of the US Department of Energy’s Reference Model vertical-axis cross-Flow Turbine were measured experimentally in a towing tank, to provide a comprehensive open dataset for validating numerical models. Performance was measured for a range of tip speed ratios and at multiple Reynolds numbers by varying the rotor’s angular velocity and tow carriage speed, respectively. A peak power coefficient CP = 0.37 and rotor drag coefficient CD = 0.84 were observed at a tip speed ratio λ0 = 3.1. A regime of weak linear Re-dependence of the power coefficient was observed above a Turbine diameter Reynolds number ReD ≈ 106. The effects of support strut drag on Turbine performance were investigated by covering the rotor’s NACA 0021 struts with cylinders. As expected, this modification drastically reduced the rotor power coefficient. Strut drag losses were also measured for the NACA 0021 and cylindrical configurations with the rotor blades removed. For λ = λ0, wake velocity was measured at 1 m (x/D = 0.93) downstream. Mean velocity, turbulence kinetic energy, and mean kinetic energy transport were compared with results from a high solidity Turbine acquired with the same test apparatus. Like the high solidity case, mean vertical advection was calculated to be the largest contributor to near-wake recovery. However, overall, lower levels of streamwise wake recovery were calculated for the RM2 case—a consequence of both the relatively low solidity and tapered blades reducing blade tip vortex shedding—responsible for mean vertical advection—and lower levels of turbulence caused by higher operating tip speed ratio and therefore reduced dynamic stall. Datasets, code for processing and visualization, and a CAD model of the Turbine have been made publicly available.
-
effects of reynolds number on the energy conversion and near wake dynamics of a high solidity vertical axis cross Flow Turbine
Energies, 2016Co-Authors: Peter Bachant, Martin WosnikAbstract:Experiments were performed with a large laboratory-scale high solidity cross-Flow Turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-Flow Turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R eD ≈ 106 or an approximate average Reynolds number based on the blade chord length R ec ≈ 2 × 105 . A simple model that calculates the peak torque coefficient from static foil data and cross-Flow Turbine kinematics was shown to be a reasonable predictor for Reynolds number dependence of an actual cross-Flow Turbine operating under dynamic conditions. Mean velocity and turbulence measurements in the near-wake showed subtle differences over the range of R e investigated. However, when transport terms for the streamwise momentum and mean kinetic energy were calculated, a similar R e threshold was revealed. These results imply that physical model studies of cross-Flow Turbines should achieve R eD ∼ 106 to properly approximate both the performance and wake dynamics of full-scale devices and arrays.
-
characterising the near wake of a cross Flow Turbine
Journal of Turbulence, 2015Co-Authors: Peter Bachant, Martin WosnikAbstract:The performance and detailed near-wake characteristics of a vertical axis, cross-Flow Turbine (CFT) of aspect ratio 1 were measured in a large cross-section towing tank. The near-wake at one Turbine diameter downstream was examined using acoustic Doppler velocimetry, where essential features regarding momentum, energy, and vorticity are highlighted. Dominant scales and their relative importance were investigated and compared at various locations in the measurement plane. Estimates for the terms in the mean streamwise momentum and mean kinetic energy equation were computed, showing that the unique mean vertical velocity field of this wake, characterised by counter-rotating swirling motion, contributes significantly more to recovery than the turbulent transport. This result sheds light on previous CFT studies showing relatively fast downstream wake recovery compared to axial-Flow Turbines. Finally, predictions from a Reynolds-averaged Navier–Stokes simulation with the commonly used actuator disk model were ...
-
reynolds number dependence of cross Flow Turbine performance and near wake characteristics
2014Co-Authors: Peter Bachant, Martin WosnikAbstract:Minimizing wake losses in wind or marine hydrokinetic (MHK) Turbine arrays is a crucial design consideration, as it has a large impact on overall energy production. To understand and mitigate these losses, interactions between Turbine wakes must be accurately predicted, with near-wakes being especially important for cross-Flow (or vertical-axis) Turbines, given their affinity for close-spaced operation. As numerical models become more accurate, validation efforts will need to take into account scale discrepancies between the numerical and physical models and their real-world applications. One such important scaling parameter is the Reynolds number, and it remains unclear what level of confidence can be placed in models validated away from full-scale Reynolds numbers. In other words, what is the minimum acceptable scale mismatch for experimental validation at which models can be said to be “accurate enough?” To address this uncertainty, we investigated—experimentally and numerically—the effects of Reynolds number on the performance and near-wake characteristics of a 3-bladed cross-Flow Turbine. Mechanical power output and overall streamwise drag were measured in a towing tank at Turbine diameter Reynolds numbers ReD = U¥D=n = 0:3‐1:3 10 6 , with performance becoming essentially Reynolds number independent at ReD = 0:8 10 6 , corresponding to an average blade chord Reynolds number Rec lU¥c=n 2:1 10 5 . Detailed measurements of the near-wake one Turbine diameter downstream were acquired via acoustic Doppler velocimetry for each Reynolds number case, showing very slight differences in the mean velocity, turbulence intensity, and Reynolds stress at the Turbine mid-height plane, i.e., the near-wake statistics were less Reynolds number dependent than the Turbine performance. The wake was also simulated using a 2-D Reynolds-averaged Navier‐Stokes (RANS) model. The performance results show poor agreement with the experimental data, due to 2-D blockage and the neglecting of blade end effects, however, an increase in performance with Re is predicted. The CFD predictions for wake characteristics are reasonably accurate on the side of the Turbine where blades are turning back into the direction of the Flow, or where dynamic stall is occurring, but Reynolds number dependence is much more exaggerated compared with the experimental data.
Lisheng Pan - One of the best experts on this subject based on the ideXlab platform.
-
Experimental Investigation on Performance of an Organic Rankine Cycle System Integrated with a Radial Flow Turbine
Energies, 2019Co-Authors: Lisheng Pan, Huaixin WangAbstract:An experimental method is used to investigate the performance of a small-scale organic Rankine cycle (ORC) system which is integrated with a radial Flow Turbine, using 90 °C hot water as a heat source. The considered working fluids are R245fa and R123. The relationship between cycle performance and the operation parameters is obtained. With constant condensing pressure (temperature), the outlet temperature of the hot water, the mass Flow rate of the hot water and the evaporator heat transfer rate increase with increasing evaporating pressure. Turbine isentropic efficiency decreases and transmission-generation efficiency increases with rising evaporating pressure. In the considered conditions, the maximum specific energy is 1.28 kJ/kg, with optimal fluid of R245fa and an optimal evaporating temperature of 69.2 °C. When the evaporating pressure (temperature) is constant, the outlet temperature of the cooling water increases, and the mass Flow rate of the cooling water decreases with increasing condensing pressure. Turbine isentropic efficiency increases and transmission-generation efficiency decreases with the rise of condensing pressure. In the considered conditions, the maximum specific energy is 0.89 kJ/kg, with optimal fluid of R245fa and an optimal condensing temperature of 29.1 °C. Turbine efficiency is impacted by the working fluid type, operation parameters and nozzle type.
-
improved analysis of organic rankine cycle based on radial Flow Turbine
Applied Thermal Engineering, 2013Co-Authors: Lisheng Pan, Huaixin WangAbstract:With attention to the drawback of specifying isentropic efficiency of expander (or Turbine) in Organic Rankine Cycle (ORC) analysis, in order to enhance reliability of analysis results, this article replaces the constant isentropic efficiency by internal efficiency of optimal radial Flow Turbine for each condition. With both analysis methods, namely internal efficiency analysis method and conventional analysis method, 14 subcritical ORC working fluids are studied with hot water of 90℃, pinch point temperature of 5℃ and condensing temperature of 30℃. Results with both analysis methods are compared. The results show that Turbine internal efficiency is determined by expansion ratio in rotor and decreases with the rise of expansion ratio in rotor. There are differences between cycle net power output with internal efficiency analysis method and that with conventional analysis method. The differences can change the results in optimizing fluid. It is significant to apply computational optimal efficiency instead of constant isentropic efficiency in ORC analysis.