Extraction energy of currents with the help of a flapping plate
Physics of processes
Its known that at cylinder flow-around two vortexes appear. Vortexes develop and separate not at the same time. As the result lift power will operate on cylinder across the flow. This lift power has a periodical character in time. Excellent research of these effects is conducted in Cornell University Fluid Dynamics Research Laboratories.
Cornell University Fluid Dynamics Research Laboratories
Vortex Hydro Energy/Cornell FDRL [Research Aeroelasticity & Vortex Induced Vibration].htm
If cylinder or another body is fixed on a moving bonding this force can set the body or its separate parts into oscillation (e.g. elastic slat). If the system of mechanical energy output is organized correctly this device can be considered as generator.
Numerous attempts to extract wind and water flow kinetic energy with the help of flexible working parts of different design were made.
Lately new interesting projects have come into view:
VIVACE converter model operating in the Low-turbulence Free Surface Re-circulating Water Tunnel
Flow Speed: 1.6 knots (0.823 m/s)
Energy Harvesting Eel Program
In Ocean Power Technologies, Inc., Energy Harvesting Eel Program power sources extracting ocean current kinetic energy with the help of oscillating elasticslat are being developed. Sea current flows around rigid fixed slat which cause vortex trail. This vortex trail flows around the slat the surface of which can wriggle under the influence of the vortex. Kinetic energy is collected from the leading edge of this slat.
Oscillating moving surface [Ocean As]
In Ocean As Company in Norway works on sea current energy extraction with the help of oscillating multilink moving surface are conducted. Mechanical energy is collected from the first link through angular oscillations of vertical axis.
Research works of this company are very important and are highly perspective. However, all these devices have a number of serious disadvantages:
o Inefficient kinetic energy extraction from approach stream. Flow energy is being extracted as the water flows along the slat surface. As the result oscillation amplitude along the slat or other elastic surface increases. Consequently, maximum energy accumulates at the end of these devices! However, the energy is being collected from the leading edge but not the rear one!? Thats why the construction of the operating device mentioned above is inefficient for extraction and transmission of energy to generator.
o Inefficient extraction and transmission of energy from the energy receiving elements (from the slat and its parts) to the generator. On the slat mechanical energy is transmitted to the end of the slat. And what we need is an opposite process, energy transmitted from the rear edge of the slat to the leading edge and then to the generator. Multilink system (slats composed of hinged members, etc.) is a poor mechanical energy transmitter.
o Multilink swiveling devices are very complex, expensive and unreliable at exploitation in marine conditions
1. Wind- hydrogenerators extracting wind and water flows kinetic energy with the help of oscillating bodies (cylinders, elastic slats, etc.) started to appear lately.
2. These generators have low coefficient of energy extraction, complicated design and high price. The reasons are the following:
— Development of these generators is based on quasistationary oscillative aerohydromechanics (for oscillations stationary aerohydrodynamics is used). Theory of nonlinear aerohydrodynamics is just being formed. Many scientists and engineers either dont know about existence of nonlinear oscillative aero-hydrodynamical effect or disregard it.
— The development of the generator construction is conducted using computation method of stationary mechanics. It is a great mistake. Such constructions will be complex, expensive, unreliable and will have heavy losses of energy and much harmful vibrations. These constructions have to be developed as a whole oscillating system.
— Special experimental, calculation and engineering techniques are needed for these generators. There are not much techniques and experience of that kind.
3. Wind power and hydroelectric generators with oscillating cylinders or elastic slat can be very effective and cheap. But we have to involve our know-how for that (to eliminate disadvantages mentioned in point 2).
4. The companies developing wind power and hydroelectric generators with oscillating bodies should be in scientific cooperation.
Our research works and developments
The use of oscillating wings produced by the companies mentioned above can be sufficiently extended. Our high technology is based on operation of wind power and hydroelectric generators in the field of nonlinear aero-hydrodynamical modes and construction of device as a whole oscillative system (KNOW-HOW).
1. Considerable experimental researches of flows and forces during oscillations of the cylinder in a wide range of frequency variations and amplitude of oscillations have been conducted. New mechanisms unknown in science are revealed, see animations below:
2. A basis of experimental results of cylinder oscillations in nonlinear oscillative mode has been formed.
3. An experimental research method of kinetic, dynamical and energy characteristics of oscillating cylinder as an oscillative system has been developed.
4. Principles of mechanical energy transmission and conditioning from approaching flow to electric generator are developed.
5. Energy conversion technique from mechanical to electrical has been worked out.
6. A method and program of device calculation as a whole oscillative system has been developed.
7. Patents on wind power and hydroelectric generators with oscillating working parts (wings, cylinders, slats and other) for 80 years period have been collected.
8. Groundwork for theory of wind power and hydroelectric generators with oscillating wing has been laid.
9. Calculation method of elastic body for energy transmission has been worked out.
Advantages of using nonlinear oscillative aero-hydrodynamical modes:
1. Lift coefficient increases. Wing water-flow stall occurs at much larger attach angles; as the result, flow energy extraction increases and generator will start operating at lower flow speed.
2. Implementation of more effective wing oscillation laws. Energy extraction simultaneously with the help of lift and frictional forces affecting the wing.
3. Reduction of hydrodynamical and aero-dynamical drag with the help of water -flow elements and oscillations.
4. Usage of added elasticity (elasticity caused by vortex structure of fluid body near oscillating wing). It will lead to volume increase of fluid medium participating in aero-hydrodynamical interaction with oscillating wing and, as the result, increasing of effective hydraulic square and coefficient of flow energy extraction.
5. Due to vortex structure near oscillating cylinder effective hydraulic square can be increased several times (see pic. 2-3).
It will lead to increase of energy extraction at the same oscillation amplitude of the cylinder. Simultaneously, power load per unit of effective hydraulic square will decrease, what will lead to increase of energy efficiency of approach stream.
Construction of device as a whole oscillative system will give the following advantages:
1. It will lead to increase of flow energy extraction and cheapening of construction;
2. Using of added elasticity instead of (or additionally) elastic member of the cylinder construction. It will lead to simplification and cheapening of the construction.
3. Using of special distribution of elastic and weight cylinder characteristics for conformance of external power supply with input characteristics of transmitting matching element. Due to these elements extraction of flow kinetic energy increases.
4. Usage of special transmitting matching elements for conformance of flow dynamic and kinematic characteristics with loading (power user). It will lead to matching of energy transmission from energy resource to generator (otherwise, energy will turn back to the flow).
5. Application of adaptive microprocessor control system will lead to ultimate output.
6. Implementation of physical effects for extracting additional kinetic energy from latent heat energy and waters pillar potential energy or atmosphere pressure:
1. Rodionov B.N., Sorokodum E.D. Vortex energy// Construction material, equipment and technologies of XX Century. — 2001, 3(26). нќін°ё,29.
2. 2. Sorokodoum E. Vortex heat-generators // New Energy Technologies. Issue # 2(5), March-Aprel 2002, p.17-18.).
See our website:
Considering our results and offers, wind- hydroelectric stations with oscillating cylinders and elastic slats will have much better aerohydrodynamic and power characteristics compared to traditional ones.
Wind- hydrogenerators with oscillating working parts can reduce several times setting cost and electric energy expenses. Its possible to assimilate production of generators suggested above from 0.1 kW to 100mW. They can be used to extract energy of wind, minor and large river flows, tidal and other sea currents.
Creation of self-supporting power supply will be possible!