Dimensionless characteristic parameters of CFD simulations and laboratory tests were selected and compared as shown in Figure The comparison of 3D-CFD simulations with laboratory test results shows a reasonable fit of the head performance curve and a worse adjustment in the efficiencies due to scale effects, torque measure accuracy due to mechanical friction in the balance brake system and in bearings, and in leaks between the impeller and the external envelop.
CFD simulations are not able to take into account these effects. Once again the efficiency values obtained by 3D-CFD are higher than the experimental ones as former confirmed.
An extended analysis based on laboratory testing and numerical modelling in a new prototype micro-propeller design is presented.
This type of machine is usually composed by a runner installed in a pipe curve, without volute or guide vane as simple as possible to be a cost-effective solution and easy to be implemented in a bypass into existing water infrastructures.
They are appropriate for operating under almost constant-flow conditions, such as in water supply systems equipped with discharge control valves or tanks with capacity to regulate. The use of the blade model configuration BMC , together with experimental tests and 3D fluid computational analyses, can help researchers and equipment manufacturers to better understand the phenomenon associated with the hydrodynamic and a turbine design.
This can lead to a greater knowledge on the interaction between the machine geometry, the hydraulic flow conditions, and the turbine performance. This paper highlights the importance of using extended testing and computational analysis which to guide the design of new energy solutions for micro-hydro schemes. These solutions come as a promising answer to cover the lack of energy in isolated or rural zones, or in pressurized systems for water transport. Ramos et al. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Academic Editor: S. Received 20 Oct Accepted 23 Nov Published 29 Feb Abstract Low-head microhydro systems for energy production are becoming accepted because of oil crises and new advances in their design and efficiencies.
Introduction Despite that researchers and equipment manufactures have paid less attention to the emerging field of low-head power engines, microturbines can provide innovative, environmental friendly, and cost-effective solutions for energy production. Turbine Design To determine optimal design results, which to lead to the best-efficiency point BEP of a prototype turbine, it is important to analyse different blade slopes i. Figure 1. Velocity vectors in a blade of a turbine propeller.
Figure 2. Scheme of a propeller: a plan view and five profiles in a blade and b parameters associated to the tracing profiles in each blade. Figure 3. Design of different profiles for each blade. Impeller configuration. Table 1. Figure 4. Characteristics curves of the micro-tubular propeller. Figure 5. Experimental facility of the micro-tubular propeller: UDV left , balance torque center , and rotational speed measurement right.
Figure 6. Separation of the boundary layer and velocity profiles. Figure 7. Flow velocity profiles obtained by UDV along the turbine: a at upstream in the nonpropeller disturbed zone, b at the upstream shaft, c in the middle of the impeller, d at downstream of the impeller. Table 2. Figure 8. Figure 9. Figure Fluid behaviour inside the micro-tubular propeller. Schematic representations of the sectioning plans for instantaneous velocity analysis.
CFD simulations for the flow velocity variation across the turbine. Table 3. Main characteristics of the micro-tubular propeller for low-head solutions. References R. Blakely and K. View at: Google Scholar R.
Simpson and A. Medium head turbine: The net head varies from 30m to m, and also these turbines require a moderate quantity of water. Example: Francis turbine. Low head turbine: The net head is less than 30m and also these turbines require a large quantity of water. Example: Kaplan turbine. Start Learning English Hindi. Kaplan turbine Francis turbine Pelton Wheel turbine Impulse turbine.
Start Now. Get Started for Free Download App. More Reaction Turbine Questions Q1. The degree of reaction of a Kaplan turbine is:. The discharge passing through a turbine, which is working under a unit head, is called as:. If the turbine has kinetic energy and pressure energy of water at its inlet, then such turbine is known as. Jet ratio m is defined as the ratio of. What is the range of the speed ratio for a Francis turbine? With respect to reaction turbines, which of the following statements is relevant?
Compared to a cylindrical draft tube, a tapered draft tube. More Turbomachinery Questions Q1. A horizontal jet of water with its cross-sectional area of 0. After impact, the jet splits symmetrically in a plane parallel to the plane of the plate.
The force of impact in N of the jet on the plate is:. The two most common types of reaction turbines are Propeller including Kaplan and Francis. Kinetic turbines are also a type of reaction turbine. A propeller turbine generally has a runner with three to six blades. Water contacts all of the blades constantly. Picture a boat propeller running in a pipe. Through the pipe, the pressure is constant; if it wasn't, the runner would be out of balance. The pitch of the blades may be fixed or adjustable.
The major components besides the runner are a scroll case, wicket gates, and a draft tube. There are several different types of propeller turbines:. Bulb turbine : The turbine and generator are a sealed unit placed directly in the water stream. Tube turbine : The penstock bends just before or after the runner, allowing a straight-line connection to the generator.
Kaplan Turbine : Both the blades and the wicket gates are adjustable, allowing for a wider range of operation. This turbine was developed by Austrian inventor Viktor Kaplan in The Francis turbine was the first modern hydropower turbine and was invented by British-American engineer James Francis in A Francis turbine has a runner with fixed blades, usually nine or more. Water is introduced just above the runner and all around it which then falls through, causing the blades to spin.
Besides the runner, the other major components include a scroll case, wicket gates, and a draft tube. Francis turbines are commonly used for medium- to high-head to 2,foot situations though they have been used for lower heads as well. Francis turbines work well in both horizontal and vertical orientations.
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