JP2015229953A - Wave power generation turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of a wave power generation turbine for generating electric power by utilizing the energy of waves.SOLUTION: A wave power generation turbine comprises: a revolving shaft arranged in a cylindrical wind tunnel and supported rotatably on an axis concentric with said cylindrical wind tunnel; and a rotor hub including turbine blades fixed on the revolving shaft and extending in radial directions. The wave power generation turbine is characterized: in that the maximum blade thickness of the turbine blades is gradually tapered forward from blade roots 10 to blade tips 9; and in that the position of the maximum blade thickness gradually shifts to the backs of the turbine blades.

Description

  The present invention relates to a wave power generator that generates power using wave energy, and more particularly to a turbine used in a vibrating water column type wave power generator.

  The oscillating water column type wave power generation device generates electricity by rotating the turbine, an air chamber composed of an external sealed chamber having a lower portion opened to the sea surface and an upper portion having an air passage to the atmosphere, and a turbine provided in the air passage. It consists of a generator that performs. When a pressure difference between the air chamber and the outside occurs due to the vertical movement of the sea surface, an air flow is generated in the air passage due to the pressure difference, and the turbine is rotated using this air flow to generate electric power.

  This power generation device is promising as a power supply source for remote islands and the like because it has a feature that there are few structural strength problems because the movable part does not directly receive wave energy, and it is advantageous in terms of maintenance.

  Conventionally, wells turbines have been mainly used as turbines for vibrating water column power generation devices (Patent Document 1).

  The Wells turbine includes a rotor hub having a plurality of symmetrical airfoil-type turbine blades mounted so that the zero lift surface is perpendicular to the rotation axis, and rotates in the same direction regardless of the air flow direction. It is a configured turbine. The Wells turbine has a feature that its structure is simple because it generates a driving force in one direction with respect to the reciprocating flow.

  On the other hand, the Wells turbine requires a start-up time because the driving force is smaller than the lift and the output torque is small. Further, there is a stall region in a range where the angle of attack is large. That is, when the flow rate of the air flow converted from the vertical kinetic energy of the sea surface increases, the turbine blades stall and a significant drop in turbine torque occurs, resulting in a problem that turbine efficiency decreases.

  In order to solve the problems of the Wells turbine, various improvement measures have been conventionally taken.

  For example, Patent Document 2 discloses a turbine in which guide blades 22 and 23 separated from a turbine blade are incorporated on the upstream side and the downstream side of the turbine blade 21 (see FIG. 7). In the turbine described in Patent Document 2, since the guide vanes 22 and 23 are disposed to be inclined so as to reduce or eliminate the turbine blade flow, stalling of the turbine blade can be reduced. However, the turbine disclosed in Patent Document 2 has a complicated structure and also has design problems such as optimization of the shape of the guide vanes 22 and 23.

  Further, in Patent Document 3, two rotor hubs 33 are fixed to an output shaft 32 so as to be spaced apart from each other in parallel, and a plurality of turbine blades 31 are arranged around the rotor hub 33 in a direction crossing the axial direction of the rotor hub 33. Disclosed is a symmetrical bladed biplane wells turbine that is arranged so as to be aligned in two rows on the same axis and in which two rows of symmetrical blade type turbine blades 31 are symmetrically arranged at an attachment angle γ so that their trailing edges face each other. (See FIG. 8). In the turbine described in Patent Document 3, since the turbine blades 31 are attached so that their trailing edges face each other, it is possible to improve the starting characteristics and the average efficiency. However, the turbine described in Patent Document 3 also has a design problem such as a complicated structure and optimization of the mounting angle γ.

  Further, in Patent Document 4, the rotating blades 43 are provided so as to be capable of rotating around the mounting shaft at the same time. A wave power turbine to be controlled is disclosed (see FIG. 9). According to the turbine described in Patent Document 4, since the blades of the turbine can be controlled to an appropriate angle according to the flow velocity of the pulsating gas, the range in which the turbine can be operated with high turbine efficiency is expanded, and the power generation efficiency is improved. be able to. However, even in the turbine described in Patent Document 4, means for detecting the reciprocating flow of gas and means for detecting the rotational speed of the rotary blade 43 are required, which further complicates the structure. In addition, a power source for rotating the rotor blades 43 is required, and the generated power is consumed, so that there is a problem that the power generation efficiency of the entire apparatus is lowered.

  As described above, the conventional wave power turbines have a complicated structure. In particular, a wave power generator installed on a remote island is required to be maintenance-free, and it must be avoided as much as possible that the failure frequency increases due to the complexity of the structure.

JP-A-53-92060 JP 54-59538 A Japanese Patent Publication No. 6-89645 JP-A-9-287546

  An object of the present invention is to reduce turbine blade stall and improve turbine efficiency while utilizing the advantage of a simple structure in a wave power turbine used in a wave power generator. is there.

  In order to solve the above-mentioned problems, the present invention is arranged in a cylindrical wind tunnel, is rotatably supported on a concentric axis with the cylindrical wind tunnel, and is fixed to the rotating shaft and extends in the radial direction. A rotor hub having a plurality of turbine blades, wherein the turbine blades gradually taper from the blade root to the blade tip, and the position of the maximum blade thickness gradually moves to the rear of the turbine blade. It is characterized by.

  The wave power turbine according to the present invention can follow the change in the air flow inflow angle in the blade radial direction as the turbine blades rotate, and the work in each blade cross section in the radial direction becomes uniform. Further, even when the flow rate of the air flow is increased, the stall of the turbine blade can be prevented, so that the turbine efficiency can be improved.

It is a perspective view of a wave power generation turbine. It is a perspective view which shows the turbine blade of the wave power generation turbine which concerns on this invention, and the flow of an air flow. FIG. 3 is a view as seen from an arrow A in FIG. 2. It is a perspective view which shows the turbine blade of the conventional wave power generation turbine, and the flow of an air flow. It is a figure which shows the relationship between the span position of a turbine blade, and an angle of attack. It is a perspective view which shows the structure of the conventional wave power generation turbine, and the flow of an air flow. It is the schematic which shows the structure of the wave power generation turbine provided with the stator blade | wing by a prior art. It is the schematic which shows the structure of the biplane turbine which inclined the turbine blade by a prior art. It is the schematic which shows the structure of the wave power turbine which made the rotary blade by conventional technology rotatable.

  Embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of a wave power generation turbine, FIG. 2 is a perspective view showing the flow of a turbine blade and an air flow of the wave power generation turbine according to the present invention, and FIG. 3 is a view as viewed from an arrow A in FIG. 4 is a perspective view showing the flow of a turbine blade and air flow of a conventional wave power turbine, FIG. 5 is a diagram showing the relationship between the span position of the turbine blade and the angle of attack, and FIG. 6 is a conventional wave power turbine. It is a perspective view which shows the structure of and the flow of an airflow.

  In FIG. 1, 1 is a cylindrical wind tunnel (air passage) for air to enter and exit between an air chamber (not shown) and outside air, 2 is a rotor hub, and 3 is rotatably supported in the cylindrical wind tunnel 1. The rotating shaft 4 is fixed to the rotor hub 2, 4 is a symmetrical blade type turbine blade extending radially from the rotor hub 3, 5 is a generator connected to the rotating shaft 3, and 6 is a cylindrical wind tunnel An air flow (reciprocating flow) 7 generated in 1 indicates the direction of rotation of the wave power turbine.

  When a pressure difference occurs inside and outside the air chamber (not shown) due to the vertical movement of the sea surface, an air flow 6 is generated in the cylindrical wind tunnel 1 due to the pressure difference. The turbine blade 4 is rotated in the direction of the rotation direction 7 by the air flow 6, and the rotor hub 2 and the rotation shaft 3 are further rotated, so that the generator 5 generates power.

  In order to elucidate the mechanism by which the turbine blade stalls, the present inventors have analyzed the flow field of air flow in a conventional wave power turbine. The result is demonstrated based on FIGS.

  FIG. 4 shows the analysis result of the air flow around the turbine blade in the conventional wave power turbine, and FIG. 6 shows the result of the analysis of the air flow around the conventional wave power turbine. 3 is a graph showing the calculation results of the angle of attack at the span position of the turbine blade.

  As apparent from FIGS. 4 and 6, the air flow that has passed through the front of the turbine blade 4 is separated from the downstream surface of the turbine blade 4. An edge stall flow 13 is formed. Further, as shown in FIG. 5, it can be seen that the angle of attack at the base of the blade is larger than the tip of the blade.

  From this analysis result, it is understood that the leading edge stall of the turbine blade is promoted by the increase of the inflow angle of the air flow at the blade root and the increase of the work amount at the blade tip.

  Here, as an angle in the same radial section of the turbine blade, the air flow inflow angle is an angle formed by the air flow inflow direction with respect to the rotation plane of the turbine blade (a plane including the rotation direction 7 in FIG. 6). The angle of attack is an angle formed by the inflow direction of the air flow with respect to the chord, which is a line segment connecting the leading edge and the trailing edge of the blade. 4 to 6, the attachment angle, which is the angle formed by the blade chord with respect to the rotation plane of the turbine blade, is 0 °, and the air flow inflow angle and the elevation angle are the same angle. ing.

  The present invention improves the turbine efficiency by making it possible to follow the change in the air flow inflow angle in the radial direction of the blade as the turbine blade rotates, and by making the work in each blade section in the radial direction uniform. It is something to be made. Hereinafter, an embodiment of a wave power turbine according to the present invention will be described with reference to FIGS.

  As shown in FIGS. 2 and 3, in the wave power turbine according to the present invention, the turbine blade 4 is formed in a gradually tapered shape from the blade root 10 to the blade tip 9, and the maximum blade thickness is obtained. The location gradually moves backward with respect to the rotational direction 7 of the turbine blade 4. The blade tip air flow 11 that has passed through the leading edge of the blade tip 9 flows along the surface of the turbine blade 4 in the vicinity of the blade tip 9 having a thin blade thickness. On the other hand, the blade root air flow 12 that has passed through the leading edge of the blade root 10 flows along the surface of the turbine blade 4 in the vicinity of the blade root 10 having a thick blade thickness. In any air flow, separation from the downstream surface of the turbine blade 4 is small and constant.

  In this embodiment as well, the mounting angle, which is the angle formed by the blade chord (the line indicated by the one-dot chain line in FIG. 3) with respect to the rotation plane of the turbine blade (the plane including the rotation direction 7 in FIG. 1). Is 0 °, and the air flow inflow angle and the elevation angle are the same.

  According to the wave power generation turbine having the above-described configuration, it is possible to follow the change in the air flow inflow angle at each span position accompanying the rotation of the turbine blade 4, and the work becomes uniform regardless of the span position. Thereby, even when the flow rate of the air flow increases, stalling of the turbine blade 4 can be prevented, so that turbine efficiency can be improved.

  In addition, the application object of this invention is not limited to the structure which made the attachment angle of the turbine blade 0 degree. For example, as shown in FIG. 8 described above, two rotor hubs are fixed to the output shaft so as to be spaced apart from each other in parallel, and a plurality of turbine blades are coaxially arranged around the rotor hub in a direction intersecting the axial direction of the rotor hub. The symmetrical blade type biplane wells turbine in which the two rows of symmetrical airfoil turbine blades are arranged in two rows and arranged symmetrically at a mounting angle γ with their trailing edges facing each other is also applied to the present invention. A configuration in which “the maximum blade thickness is gradually tapered from the blade root to the blade tip of the turbine blade and the position of the maximum blade thickness gradually moves toward the rear of the turbine blade” can be applied.

  The present invention can be used for a wave power generation turbine used in a wave power generation apparatus.

DESCRIPTION OF SYMBOLS 1 Cylindrical wind tunnel 2 Rotor hub 3 Rotating shaft 4 Symmetric wing | blade type | mold turbine blade 5 Generator 6 Air flow (reciprocating flow)
7 Rotating direction 8 Same radius cross section 9 Blade tip 10 Blade root 11 Blade tip air flow 12 Blade root air flow 13 Blade leading edge stall flow

Claims (1)

A rotating shaft disposed in a cylindrical wind tunnel and rotatably supported on a concentric axis with the cylindrical wind tunnel, and a rotor hub having a plurality of turbine blades fixed to the rotating shaft and extending in the radial direction. ,
The turbine blade is configured such that the maximum blade thickness is gradually tapered from the blade root to the blade tip, and the position of the maximum blade thickness is gradually shifted to the rear of the turbine blade. Turbine.

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