scholarly journals Pengaruh Sudut Pengarah Aliran Pada Turbin Air Crossflow Tingkat Dua Terhadap Putaran dan Daya

2018 ◽  
Vol 3 (1) ◽  
pp. 35 ◽  
Author(s):  
Satria Candra Laksmana ◽  
A'rasy Fahruddin ◽  
Ali Akbar
Keyword(s):  
Water Flow ◽  
Large Scale ◽  
Flow Direction ◽  
Mechanical Energy ◽  
Water Discharge ◽  
Turbine Blades ◽  
Cross Flow ◽  
Small Scale ◽  
Direction Angle ◽  
Study Planning

The potential of hydro energy is very large both for large scale and for small scale. Until now, the need for energy continues to increase, so that energy is a very important element in the development of a country or a region. Cross-flow turbines are one type of turbine that is often used for PLTMH. In this study planning a cross-flow water turbine applied to the height and amount of water per second in the irrigation channel water flow, this water flow will rotate the turbine shaft to produce mechanical energy. With variations in the direction of the turbine flow direction, namely 30o, 35o, and 40o, and the same variation of water discharge 10,5 L / s, 21 L / s and 31,5 L / s to determine the effect on the rotation and the power produced. In this study with 12 turbine blades, 30o blade angle, 40o flow direction angle, and 31.5 L / s water discharge obtained the highest first stage turbine rotation value is 478 rpm. Whereas at the flow direction angle of 30o with the same water discharge which is 31.5 L / s so that the first stage of the turbine is obtained is 296 rpm.

scholarly journals The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery

1994 ◽  
Author(s):  
Roger W. Ainsworth ◽  
John L. Allen ◽  
J. Julian M. Batt
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Flow Direction ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Fast Response ◽  
Rotor Blades ◽  
Small Scale ◽  
Hot Wire ◽  
Flow Measurements

The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al [1988], Epstein et al [1984]. Ainsworth et al [1988]), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high pressure flows required for correct Reynolds numbers, Furthermore some laser techniques require a longer runtime than these transient facilites permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfil this perceived need. This paper describes advances made in the design, construction, and testing of two and three dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques which have previously been successfully used on the surface of rotor blades (Ainsworth, Dietz and Nunn [1991]). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology which has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive programme of testing large scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimising the design of the small scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained is compared with (PD solutions of the unsteady viscous flow-field.

scholarly journals A Double Nozzle Cross Flow Turbine Fluid Flow Dynamics

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Corvis L. Rantererung ◽  
Sudjito Soeparman ◽  
Rudy Soenoko ◽  
Slamet Wahyudi
Keyword(s):  
Fluid Dynamics ◽  
Fluid Flow ◽  
Turbine Blade ◽  
Mechanical Energy ◽  
Water Discharge ◽  
Cross Flow ◽  
Flow Dynamics ◽  
Runner Blade ◽  
Turbine Performance ◽  
Turbine Runner

The dynamics of fluid flow are very important to the process of converting water energy into mechanical energy at the nozzle double runner cross flow turbine blade. Fluid dynamics of a jet of water from a nozzle release energy as the water crosses the cross flow turbine runner. This research aims to improve turbine performance and the effectiveness of fluid flow dynamics that drive cross flow turbine runner blades using double nozzles. The method of research using a cross flow turbine with double nozzle is a combination of vertical and horizontal nozzles. The turbine runner casing and blade are made of transparent acrylic material so that the flow dynamics can be observed directly. The laboratory scale double nozzle cross flow turbine is comprised of 24 blades, 3 mm thick, 40 mm long and 200 mm runner blade diameter. Test the performance of the turbine by measuring rotation, torque, and power, and by photographing the dynamics of the fluid flow that drives the turbine runner blade. The results of the study found that the visualization of the dynamics of fluid flow in turbines with double nozzles is more regular, evenly distributed, focused, and directed, moving the turbine runner blade cross flow so as to be able to increase turbine performance higher. The highest double nozzle cross flow turbine performance is 6.04 Watt power and 81.68% efficiency, at a water discharge of 0.22 liters /s.

Self-Excited Vibration of Cross-Shaped Tube Bundle in Cross Flow

2002 ◽  
Author(s):  
Fumio Inada ◽  
Takashi Nishihara ◽  
Akira Yasuo ◽  
Ryo Morita ◽  
Akihiro Sakashita ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Tube Bundle ◽  
Cross Flow ◽  
Small Scale ◽  
Design Guideline ◽  
Shaped Tube ◽  
Excited Vibration ◽  
Scale Test ◽  
Flexible Tubes

Cross-shaped tube bundle is proposed for a lower plenum structure in a next generation LWR. Vibration response of cross-shaped tube bundle in cross flow has been measured in water tunnel tests. First, small-scale test was conducted. Tests were conducted with 3×3 flexible tubes as well as single flexible tube in rigid tube bundle. The flexible tubes could vibrate in lift, drag, and torsional direction. The effect of arrangements of tube bundle and the natural frequency ratio of bending and torsional vibrations were considered. Second, a large-scale test was conducted for only one case to check the effect of Reynolds number, in which Reynolds number was 10 times larger than that of small-scale test. In all the cases, large amplitude vibration could appear when the flow velocity became larger than a critical value, and a self-excited vibration was found to occur. The nondimensional critical gap velocity of the large-scale test agreed well with that of the small-scale test, which suggested that the effect of Reynolds number was not so large. A design guideline to prevent self-excited vibration was proposed for cross-shaped tube bundle.

The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery

1995 ◽  
Vol 117 (4) ◽  
pp. 625-634 ◽  
Author(s):  
R. W. Ainsworth ◽  
J. L. Allen ◽  
J. J. M. Batt
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Flow Direction ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Fast Response ◽  
Rotor Blades ◽  
Small Scale ◽  
Hot Wire ◽  
Flow Measurements

The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al., 1988; Epstein and Guenette, 1984; Ainsworth et al., 1988), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high-pressure flows required for correct Reynolds numbers. Furthermore, some laser techniques require a longer run-time than these transient facilities permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfill this perceived need. This paper describes advances made in the design, construction, and testing of two and three-dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques that have previously been successfully used on the surface of rotor blades (Ainsworth et al., 1991). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology that has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive program of testing large-scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimizing the design of the small-scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained are compared with CFD solutions of the unsteady viscous flow-field.

Wormholing in anisotropic media: Pore orientation effect on large-scale patterns

2020 ◽  
Author(s):  
Roi Roded ◽  
Piotr Szymczak ◽  
Ran Holtzman
Keyword(s):  
Large Scale ◽  
Flow Direction ◽  
Hierarchical Structures ◽  
Anisotropic Media ◽  
Viscous Fingering ◽  
Reactive Flow ◽  
Small Scale ◽  
Microfluidic Channels ◽  
Permeability Evolution ◽  
Scale Invariant

<p>The dissolution of fractured or porous media by reactive flow is often occurring preferentially, forming highly conductive channels, so-called “wormholes”. Wormhole formation prevails in subsurface karst where it can form extensive speleological systems, and is also significant for a large range of applications, e.g. well acidizing or CO<sub>2</sub> geo-sequestration. The underlying mechanism involves positive feedback between reaction and transport— the flow pathways that focus the reactive flow dissolve preferentially and increase their conductivity, and in turn their flow. An increased pressure ahead of the longer wormholes screens off the shorter ones, which ultimately cease to grow. Over time, the characteristic spacing between active (growing) wormholes increases, while their number declines, which results in a hierarchical scale-invariant distribution of wormhole lengths. Interestingly, a variety of other pattern-forming processes in nature show a similar competitive dynamics and emergent of hierarchical structures, with examples ranging from viscous fingering to crack propagation in brittle solids and side-branches growth in crystallization [1].</p><p>The importance of wormholing and its intriguing dynamics motivated intensive research, including on the emergence of reactive-infiltration instabilities [2], as well as on the effects of medium heterogeneity on the wormhole growth. Here, we study wormholing in anisotropic media using a network model of regular geometry— longitudinal channels (aligned along the main flow direction) and transverse ones, of a different average cross-section. Our simulations show that anisotropy substantially affects wormholing, controlling the characteristic spacing between the wormholes and the overall permeability evolution. In the case of wider transverse channels, wormhole interaction via the pressure field is enhanced, resulting in stronger wormhole competition and hence larger spacing. Conversely, in the extreme case of very narrow transverse channels, spacing becomes minimal and neighboring wormholes tend to merge. Simulations further reveal that narrow transverse channels promote the emergence of thinner and more conical wormholes with several side-branches.</p><p>Additionally, we discuss the relation between the wormhole development in an anisotropic medium and viscous fingering phenomena in a network of microfluidic channels [3]. Despite many similarities between these systems we also find important differences— while the spacing between viscous fingers increases linearly with anisotropy, the corresponding relation for wormholes turns out to be nonlinear. This nonlinearity could be attributed to the effect of anisotropy on wormhole shape and advancement velocity and is of interest for future investigation. Our findings contribute to the understanding of wormholing in geological systems and demonstrate how the small-scale features can fundamentally affect the resulting large-scale morphologies.</p><p>[1] Krug, J., Adv. Phys., 46, 139, 1997</p><p>[2] Ortoleva, P. et al, Amer. J. Sci., 287, 1008, 1987</p><p>[3] Budek, A. et al, Phys. Fluids, 27, 112109, 2015</p>

scholarly journals Subsurface flow mixing in coarse, braided river deposits

2016 ◽  
Vol 20 (5) ◽  
pp. 2035-2046 ◽  
Author(s):  
Emanuel Huber ◽  
Peter Huggenberger
Keyword(s):  
Large Scale ◽  
Hyporheic Zone ◽  
Flow Direction ◽  
Subsurface Flow ◽  
Small Scale ◽  
Braided River ◽  
Flow Deviation ◽  
River Deposits ◽  
Advective Mixing ◽  
The Impact

Abstract. Coarse, braided river deposits show a large hydraulic heterogeneity on the metre scale. One of the main depositional elements found in such deposits is a trough structure filled with layers of bimodal gravel and open-framework gravel, the latter being highly permeable. However, the impact of such trough fills on subsurface flow and advective mixing has not drawn much attention. A geologically realistic model of trough fills is proposed and fitted to a limited number of ground-penetrating radar records surveyed on the river bed of the Tagliamento River (northeast Italy). A steady-state, saturated subsurface flow simulation is performed on the small-scale, high-resolution, synthetic model (size: 75 m  ×  80 m  ×  9 m). Advective mixing (i.e. streamline intertwining) is visualised and quantified based on particle tracking. The results indicate strong advective mixing as well as a large flow deviation induced by the asymmetry of the trough fills with regard to the main flow direction. The flow deviation induces a partial, large-scale rotational effect. These findings depict possible advective mixing found in natural environments and can guide the interpretation of ecological processes such as in the hyporheic zone.

Variable discharge alters habitat suitability for benthic algae and cyanobacteria in a forested Mediterranean stream

2010 ◽  
Vol 61 (4) ◽  
pp. 441 ◽  
Author(s):  
Elisabet Tornés ◽  
Sergi Sabater
Keyword(s):  
Water Flow ◽  
Large Scale ◽  
Light Availability ◽  
Benthic Algae ◽  
High Water ◽  
Algal Community ◽  
Small Scale ◽  
Low Velocity ◽  
Substratum Type ◽  
Mediterranean Stream

Large-scale algal community patterns can be understood by studying organisation within patches. Spatial heterogeneity in light and substratum type may affect the biomass and community composition of benthic algae and cyanobacteria. We compared the effects of these factors at the species level in two reaches differing in canopy cover in a forested Mediterranean stream in winter (high water flow) and late spring (low water flow). Partial redundancy analyses revealed that the major determinants of species distribution were strongly associated with variations in measured environmental variables. Light availability, the Reynolds number and substratum type were the main factors accounting for the algal and cyanobacterial distribution. Factors affecting algal distribution varied between hydrological periods, suggesting that some species had specific requirements whereas others had a wider tolerance to environmental conditions. Our results demonstrated that the hydraulic conditions (low velocity v. high velocity) influence small-scale heterogeneity in streams, and that this affects benthic community distribution.

Control of Large-Scale Heat Transport by Small-Scale Mixing

2006 ◽  
Vol 36 (10) ◽  
pp. 1877-1894 ◽  
Author(s):  
Paola Cessi ◽  
W. R. Young ◽  
Jeff A. Polton
Keyword(s):  
Heat Transport ◽  
Mixed Layer ◽  
Large Scale ◽  
Scaling Laws ◽  
Mechanical Energy ◽  
Small Scale ◽  
Thermocline Depth ◽  
Leading Order ◽  
Diapycnal Diffusivity ◽  
The Mean

Abstract The equilibrium of an idealized flow driven at the surface by wind stress and rapid relaxation to nonuniform buoyancy is analyzed in terms of entropy production, mechanical energy balance, and heat transport. The flow is rapidly rotating, and dissipation is provided by bottom drag. Diabatic forcing is transmitted from the surface by isotropic diffusion of buoyancy. The domain is periodic so that zonal averaging provides a useful decomposition of the flow into mean and eddy components. The statistical equilibrium is characterized by quantities such as the lateral buoyancy flux and the thermocline depth; here, scaling laws are proposed for these quantities in terms of the external parameters. The scaling theory predicts relations between heat transport, thermocline depth, bottom drag, and diapycnal diffusivity, which are confirmed by numerical simulations. The authors find that the depth of the thermocline is independent of the diapycnal mixing to leading order, but depends on the bottom drag. This dependence arises because the mean stratification is due to a balance between the large-scale wind-driven heat transport and the heat transport due to baroclinic eddies. The eddies equilibrate at an amplitude that depends to leading order on the bottom drag. The net poleward heat transport is a residual between the mean and eddy heat transports. The size of this residual is determined by the details of the diapycnal diffusivity. If the diffusivity is uniform (as in laboratory experiments) then the heat transport is linearly proportional to the diffusivity. If a mixed layer is incorporated by greatly increasing the diffusivity in a thin surface layer then the net heat transport is dominated by the model mixed layer.

scholarly journals Performance test of Pikohidro Cross flow Water Turbine using multilevel double penstock

Teknomekanik ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 76-80
Author(s):  
Purwantono Purwantono ◽  
Bahrul Amin ◽  
Abdul Aziz ◽  
Jasman Jasman ◽  
Andre Kurniawan
Keyword(s):  
Water Flow ◽  
Performance Test ◽  
Flow Analysis ◽  
Cross Flow ◽  
Water Velocity ◽  
Small Scale ◽  
Excess Water ◽  
Water Turbine ◽  
The Stability ◽  
Turbine Construction

This study aims to examine the performance of pico hydro scale cross flow water turbines using multilevel double penstock as a conductor of water flow.  Multilevel double penstock is used to reduce the transportation process from highways that are affordable to four-wheeled vehicles / cars to the location of the installation of the turbine.  This condition causes the need for small-scale water turbine designs with lightweight construction with a kock down system.  Overall the picohidro scale turbine construction is needed relatively cheaper transportation costs, so that people who have not been reached by the PLN network can be touched by small and cheap electricity. Turbine construction data has a runner diameter of 170 mm, body dimensions 200 mm x 300 mm x 250 mm, frame 250 mm x 800 mm. Pool tando 600 mm x 1200 mm and penstock length 16m. The power produced is theoretically around 2500 watts, with a data flow of 50 liters / second and a water level of 8 m. 65% efficiency. The research method is analyzing the double penstock water flow, by making paralon pipes in stages, ranging from 5 incci diameter, 4 inches and 3 inches, flow analysis approach using a gradient line, where the incoming water velocity and water velocity come out until entering the transmitting pipe. The performance results of this turbine provide an average actual power of up to 2000 watts. The stability of the inlet water condition is used by the Tando pond as a water bath. If there is excess water in the sediment tank, the water gate is used out, where excess water will automatically flow into the exhaust channel.

Sign in / Sign up

Export Citation Format

Share Document