GB2497763A - Air injection system for reducing hydrodynamic loads on water turbine blades - Google Patents

Air injection system for reducing hydrodynamic loads on water turbine blades Download PDF

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Publication number
GB2497763A
GB2497763A GB1121892.2A GB201121892A GB2497763A GB 2497763 A GB2497763 A GB 2497763A GB 201121892 A GB201121892 A GB 201121892A GB 2497763 A GB2497763 A GB 2497763A
Authority
GB
United Kingdom
Prior art keywords
blade
turbine
text
fluid
orifice
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1121892.2A
Other versions
GB201121892D0 (en
Inventor
Graeme Mackie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ocean Flow Energy Ltd
Original Assignee
Ocean Flow Energy Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ocean Flow Energy Ltd filed Critical Ocean Flow Energy Ltd
Priority to GB1121892.2A priority Critical patent/GB2497763A/en
Publication of GB201121892D0 publication Critical patent/GB201121892D0/en
Priority to GB1222892.0A priority patent/GB2499700B/en
Priority to PCT/GB2012/053179 priority patent/WO2013093452A1/en
Publication of GB2497763A publication Critical patent/GB2497763A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B11/00—Parts or details not provided for in, or of interest apart from, the preceding groups, e.g. wear-protection couplings, between turbine and generator
    • F03B11/002—Injecting air or other fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/26—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy
    • F03B13/264—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy using the horizontal flow of water resulting from tide movement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B15/00—Controlling
    • F03B15/02—Controlling by varying liquid flow
    • F03B15/04—Controlling by varying liquid flow of turbines
    • F03B15/06—Regulating, i.e. acting automatically
    • F03B15/18—Regulating, i.e. acting automatically for safety purposes, e.g. preventing overspeed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B17/00—Other machines or engines
    • F03B17/06—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head"
    • F03B17/061—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head" with rotation axis substantially in flow direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B3/00—Machines or engines of reaction type; Parts or details peculiar thereto
    • F03B3/12—Blades; Blade-carrying rotors
    • F03B3/121—Blades, their form or construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B3/00—Machines or engines of reaction type; Parts or details peculiar thereto
    • F03B3/12—Blades; Blade-carrying rotors
    • F03B3/126—Rotors for essentially axial flow, e.g. for propeller turbines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/10—Purpose of the control system
    • F05B2270/101—Purpose of the control system to control rotational speed (n)
    • F05B2270/1011—Purpose of the control system to control rotational speed (n) to prevent overspeed
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Abstract

A water turbine blade 1 has at least one orifice 2 on the suction face of the blade 1 and a fluid passageway 4 in communication with the at least one orifice 2. A fluid such as air is provided to the orifice(s) 2 to reduce hydrodynamic loads on the blade e.g. to reduce over speed. The orifice(s) 2 may be located towards the tip of the blade, and a barrier 3 may be provided on the blade to prevent bubbles migrating to the radially inner region of the blade. The fluid may be compressed air, and may be provided via a passage 12 in the turbine shaft 11. Orifices 2 may be provided on both the suction and pressure faces of the blade, and may be located towards the leading edge of the blade.

Description

System for Reducing 1-lydrodynarnic Loads on Turbine Blades in Flowing Water
Field of the Invention
The prese.nt invent on relates to a system and method for reducing hydrodynamic loads on turbine blades in flowing water such as tidal streams, ocean currents and rivers, and iii particular to reducing the effectiveness of the turbine under flow conditions that exceed the rated flow speed by altering the hydrodynamic forces generated by an element of the blade.
Background of the Invention
the present invention relates to horrzontal axis turbines.
Horizontal axis turbines operating in tidal stream, liver and ocean currents have a turbine diameter selected to deliver a certain shaft power at a particular speed of water flow, often referred to as the rated speed of flow for the turbine. The shaft power delivered by the turbine is used to overcome die resistive torque of some form of power take-off device such as an electricity generator. If the turbine experiences flow speeds greater than the rated flow speed then the power generated by the turbine can ovetwhehu the power take-off device by delivering too great a shaft torque that if not absorbed by the power take-off device can lead to overspeed of die turbine and the power take-off device that is directly conpled to it.
One solution to this problem is to reduce the torque delivered by the turbine at the higher flow speeds by changing the turbine blade angle of attack to the flow such that the hydrodynamic lift force and therefore shaft torque generated by the turbine is reduced. This change in angle of attack is generally referred to as altering the pitch angle of the blades and turbines that allow such adjustment are referred to as controllable pitch turbines. Controlhng the pitch requires some actuation mechanism sncii as gears, servo motors or hydraulic actuators to adjust the pitch angle and such mechanisms can he subject to failure. The consequences of failure of the pitch control mechanism can be an increase in the hyciroclynarnic forces generated through the blade being incorrectly angled to the direction of flow. This results iti increased driving torque leading to overspeed of the power take-off device and also increased blade loading leading to structural failure of the blade.
Another solution fbr reducing the torque delivered by the blade under incrcased flow conditions is to induce stall in the flow around the blade by increasing the induced angle of attack by slowing down the speed of rotation of the turbine. This can be achieved by increasi rig the resistive torque of the power take-off device. Blade stall will lead to a reduction in the driving torque and axial drag hut it is difficult to maintain the turbine in stall mode while delivering a steady level of torque to the power take-off device. In addition the fluctuating hydrodynaniic forces when operating in the stall mode can lead to unacceptable ievels of vibration.
It would therefore he desirable to provide a system for reducing hydrodynamic loads on turbine blades in marine currents that does not involve adjusmient to the blade pitch setting or inducing blade stall.
Sumniary of thc Invention According to a first aspect of the invention there is provided a turbine blade as specified in Claim 1.
Preferred features of the turbine blade are set otrt in the claims dependent on Claim 1
and/or the description.
According to a second aspect of the invention there is provided a turbine as specified in Claim 10.
Preferred features of the turbine are set out in the claims dependent on Claim 10 and/or
the description.
According to a third aspect of the invention there is provided a method of reducing the hydrodynamic load on a turbine Made in marine currents as specified in Claim 20.
Preferred features of the method are set out in the claims dependent on Claim 20 and/or
the description.
A hoj-izontal axis turbine preferably has two or more blades where the outer portion of the blade towards the Made tip has orifices towards the leading edge on the suction face of the blade or on both the pressure and suction faces of the blade.
Preferably, a conduit running up from thc root of thc blade supplies the orifices with compressed ai.
The pipe may be supplied with compressed fluid such as compressed air hy a system involving an fluid inlet pipe that has an opening above the waterline which is connected to a compressor that pumps the compressed fluid through a coupling, and preferably into a hollow bore on die centreine of the turbine drive shaft from where the compressed fluid is distributed to the various blade fluid supply pipes.
Advantageously, fluid is distributed to blade fluid supply pipes through the blade hub.
The invention provides a system for reducing the effectiveness of the turbine under flow conditions that exceed the rated flow speed by altering the hydrodynamie forces generated by an element of the blade. TIris is achieved by discharging air around an element of the blade so that the hydrodynamic lift and drag forces on the section of blade local to the discharge of air are significantly altered.
The discharge of air under pressure on the pressure face of the blade which is the upstream face of the blade will lead to a reduction iii the viscous drag forces on that surface of the blade. The discharge of air under pressure on the suction face of the blade which is the downstream face of the blade will lead to a reduction in the suction force and viscous drag force on the blade. However, unlike operation in the stall regime the reduction in driving torque and turbine drag with air injection does not lead to torque control instability and is analogous to operating a turbine of smaller eiameter outwith the stall region of operation.
Brief Description of the Drawings
In the diawings, which illustrate preferred embodiments of the invention: Figure 1 is a schematic representation of a typical turbine blade; Figure 2 is a schematic cross-sectional plan view of a turbine blade according to the invention; and Figure 3 is a schematic representation of a turbine according to the invention.
Detailed Description of the Preferred Embodiments
Figure 1 shows a typical blade 1 fitted with multiple orifices 2. Optionally a plate 3 can be attached to the blade I to provide an aerated section of the blade and a non-aerated section of the blade. The plate extends outward from the cuter surface of the blade I. \Xithout the plate 3, when the blade is at the bottom of its rotational path due to the buoyancy of the air bubbles the air bubbles would migrate to the non-aerated section of the blade along the outer surfhce of the blade.
Figure 2 shows the blade i in cross-sectional plan view. In use one side of the blade I is subject to a positive pressure and the other to a negative pressure. A centre air supply pipe 4 and branch pipes 5, 6 catty air to orifices 2 on the pressure side P and the suction side S of the blade I respectively.
Air may he supplied to the orifices in a number of chiffetetit ways. Figure 3 shows one possible arrangement for supplying air to the blades which consists of a supply pipe 7 piercing the water surface. Air from this supply pipe is compressed by a compressor 8 and fed via a noEl-return valve 9 to a conpling in the form of a swivel 10 that connects the compressed air supply to the turbinc shaft 11 which has a centreine bore hole 12, the bore hole 12 having an inlet 12' in the side wall of the turbine shaft II. The swivel 10 provides a fluid passageway that is in fluid communication with the inlet 12' of bore 12. 1iie swivel 10 is fitted with seals 13 to prevent the air escaping. The turbine shaft ii is coupled to some power take-off device 14 such as an electrical generator.
There is a hack pressure due to the head of water \vhich varies depending upon whether the blade is at the top or bottom 01 some intermediate position of its swept rotation. Flow regulating valves 15 can be fitted to ensure that the flow is distributed correctly. The regulating valve 15 is a non-return valve which prevents ingress of water via the orifices 2.
Figure 3 illustrates and alternative arrangement of air supply pipes 4 in the lower hlade of die turhine, where more than one air disihution pipe 4 is provided in each hlade 1. The air distribution pipes 4 are controlled by valves 16 such that the air can be supplied selectively to more than one set of orifices.
The direction of water flow in this arrangement is shown as 17.

Claims (1)

  1. <claim-text>Claims 1. A turbine blade, t]1e blade having a pressure face and a suction face, wherein the blade includes at least one orifice on the suction face of the blade and a fluid passageway in fluid comnuinicauon with the at least one orifice.</claim-text> <claim-text>2. A turbine blade according to Claim I wherein at least one orifice is provided on each of t]1e pressure arid suction faces and a fluid passageway is in fluid communication with the at least one orifice on both the suction and pressure faces.</claim-text> <claim-text>3. A turbine blade according to Claims I or 2, wherein die blade has a tip and wliereii die or each orifice is situated towards the tip of the blade.</claim-text> <claim-text>4. A turbine blade accorditig to atly preceding claim, wherein the blade has a leading edge and wherein the at least one orifice is situated towards the leading ctlge of the blade.</claim-text> <claim-text>5. A turbine blade according to any preceding claim, wherein die outer surface of the blade comprises a first section and a second section, wherein thc or each orifice are in fluid communication with the first section and wherein the first and second sections are separated by a harrier extending from the outer surface of the blade.</claim-text> <claim-text>6. A turbine blade according to any preceding claim, wherein the fluid passageway in fluid communication with the at least one orifice is a conduit.</claim-text> <claim-text>7. A turbine blade according to Claim 6, wherein the fluid passageway in communication with at least otie orifice comprises a plurality of conduits, each conduit in fluiel communication with at least one orifice.</claim-text> <claim-text>8. A turbine blade according to any preceding claim, further inclutling flow control nieatis, the flow control means cotifigured to control the flow of fluid to the at least one orifice.</claim-text> <claim-text>9. A turbine blade according to Claim 8, wherein the flow control means includes one or more valve5 10. A turbine including at least one blade according to any of Claitns I to 9, the turbine further iticluding a shaft mounting the at least otie blade, the shaft including a shaft fluid passageway, the shaft fluid passageway having an inlet and an oudet, die outlet being in fluid communication with the fluid passageway of the blade.11. A turbine according to Claim 10, wherein the inlet of the shaft fluid passageway is situated lfl a side wall of the shaft.12. A turbine according to Claim 10 or 11, further inducing a coupling, the coupling being mounted on the shaft for relative rotation between the coupling and the shaft, the coupiing having an inlet and an ontlct, the outlet of the coupling being in fluid conimunicatlon with tile inlet of the shaft fluid passageway.13. A turbine accordi ig to Claim 12, wherein the couplilig surrounds the shaft.14. A turbine according to Claim 13 when dependent on Claim 11, wherein the outlet of the coupiing is in fluid communication with the inlet of the shaft fluid passageway.15. A turbine according to any of Claims 10 to 14, further including a power take off device.16. A turbine according to any of (Ilairns 12 to 15, including a pump or compressor liaving a fluid inlet arid a fluid outlet, wherein the fluid outlet is attached to inlet of snd coupling.17. A turbine according to Claim 16, further including a non-return flow control situated between the conipressor outlet and the inlet of the said coupling.18. A turbine according to Claim 16 or 17, wherein the fluid is air.19. A turbine aeeoreing to any of Claims 10 to 18, wherein the said turbine is a horl2ontal axis turbine.20. A method of reducing hydrodynamic load on a turbine blade in marine currents comprising the step of: i) mounting a turbine according to any of Claims 10 to 19 in a body of flowing water; ii) attaching the turbine to a source of pressurised fluid; iii) passing the pressurised fluid through orifices in the turbine blade.21. A method of reducing hydrodynamic l(iad-according to Claim 20, comprising the further step of controffing the flow and/or the pressure of the pressurised fluid through tlie orifices in the turbine blade to degree of hydrodynanfle load reduction.</claim-text>
GB1121892.2A 2011-12-20 2011-12-20 Air injection system for reducing hydrodynamic loads on water turbine blades Withdrawn GB2497763A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB1121892.2A GB2497763A (en) 2011-12-20 2011-12-20 Air injection system for reducing hydrodynamic loads on water turbine blades
GB1222892.0A GB2499700B (en) 2011-12-20 2012-12-19 System for reducing hydrodynamic loads on turbine blades in flowing water
PCT/GB2012/053179 WO2013093452A1 (en) 2011-12-20 2012-12-19 System for reducing hydrodynamic loads on turbine blades in flowing water

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1121892.2A GB2497763A (en) 2011-12-20 2011-12-20 Air injection system for reducing hydrodynamic loads on water turbine blades

Publications (2)

Publication Number Publication Date
GB201121892D0 GB201121892D0 (en) 2012-02-01
GB2497763A true GB2497763A (en) 2013-06-26

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GB1121892.2A Withdrawn GB2497763A (en) 2011-12-20 2011-12-20 Air injection system for reducing hydrodynamic loads on water turbine blades
GB1222892.0A Active GB2499700B (en) 2011-12-20 2012-12-19 System for reducing hydrodynamic loads on turbine blades in flowing water

Family Applications After (1)

Application Number Title Priority Date Filing Date
GB1222892.0A Active GB2499700B (en) 2011-12-20 2012-12-19 System for reducing hydrodynamic loads on turbine blades in flowing water

Country Status (2)

Country Link
GB (2) GB2497763A (en)
WO (1) WO2013093452A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105221321A (en) * 2014-06-25 2016-01-06 上海电气风电设备有限公司 The open blade structure of ocean current power generation unit inner chamber

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016207977A1 (en) * 2016-05-10 2017-05-11 Voith Patent Gmbh Impeller for a hydraulic machine

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GB2186033A (en) * 1986-02-28 1987-08-05 Nei International Research & D Wind turbine
US20080317598A1 (en) * 2007-06-25 2008-12-25 General Electric Company Power loss reduction in turbulent wind for a wind turbine using localized sensing and control
EP2014911A2 (en) * 2007-03-20 2009-01-14 Alstom Hydro France Hydraulic machine and method for preventing the wear of such a machine
US20100014970A1 (en) * 2007-01-05 2010-01-21 Lm Glasfiber A/S Wind turbine blade with lift-regulating means in form of slots or holes
US20110103950A1 (en) * 2009-11-04 2011-05-05 General Electric Company System and method for providing a controlled flow of fluid to or from a wind turbine blade surface
GB2486699A (en) * 2010-12-23 2012-06-27 Tidal Generation Ltd Rotor blades and rotor assemblies for water flow generator turbines

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Publication number Priority date Publication date Assignee Title
GB2186033A (en) * 1986-02-28 1987-08-05 Nei International Research & D Wind turbine
US20100014970A1 (en) * 2007-01-05 2010-01-21 Lm Glasfiber A/S Wind turbine blade with lift-regulating means in form of slots or holes
EP2014911A2 (en) * 2007-03-20 2009-01-14 Alstom Hydro France Hydraulic machine and method for preventing the wear of such a machine
US20080317598A1 (en) * 2007-06-25 2008-12-25 General Electric Company Power loss reduction in turbulent wind for a wind turbine using localized sensing and control
US20110103950A1 (en) * 2009-11-04 2011-05-05 General Electric Company System and method for providing a controlled flow of fluid to or from a wind turbine blade surface
GB2486699A (en) * 2010-12-23 2012-06-27 Tidal Generation Ltd Rotor blades and rotor assemblies for water flow generator turbines

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105221321A (en) * 2014-06-25 2016-01-06 上海电气风电设备有限公司 The open blade structure of ocean current power generation unit inner chamber

Also Published As

Publication number Publication date
GB2499700B (en) 2017-12-13
GB201222892D0 (en) 2013-01-30
WO2013093452A1 (en) 2013-06-27
GB201121892D0 (en) 2012-02-01
GB2499700A (en) 2013-08-28

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