JPH0689645B2 - Wave Power Generator Using Symmetrical Wing Type Biplane Wells Turbine with Mounting Angle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for converting energy of waves into a mechanical rotary motion, more specifically, a symmetrical blade type biplane wells used in a wave power generation device. It is about turbines.

(Prior art) In Japan, which is surrounded on all sides by sea and has few fossil fuel resources such as coal and oil, effective use of ocean energy is
This is one of the technical issues that must be resolved toward the diversification of energy supply sources.

Among the various ocean energies such as temperature difference, wave, tide, ocean current, concentration difference, and living things, in order to use wave energy, the vertical motion of the wave is converted into air pressure, and the air flow generated by this conversion is used as a turbine. There is a device for rotating the turbine, and one of them is a wave power generation device using a turbine having symmetrical blades (hereinafter referred to as "wells turbine").

In particular, a type in which two turbine rotors are coaxially arranged is called a biplane wells turbine.

As a conventional biplane type Wells turbine, there is one as shown in FIG. A rotor hub 3 is fixed to an output shaft 2 of the multi-leaf type Wells turbine 1, and a plurality of turbine blades 4 are coaxially arranged in two rows around the rotor hub 3 in a direction intersecting the axial direction of the rotor hub 3.

This biplane type Wells turbine 1 is used in a wave power generation device as shown in FIG. In FIG. 9, the wave power generation device 5 has an air chamber 6 that converts vertical movement of waves into air pressure, and a guide 7 that guides an air flow generated by this conversion to the outside or the inside of the air chamber. A power generation unit 9 having a built-in power generator is arranged so as to form an air passage 8 inside 7, and the turbine 1 is connected to the power generation unit 9 via an output shaft (not shown).

Next, the operation of this power generator and turbine will be described.

For example, when the sea level in the air chamber 6 rises as shown by arrow A in the figure, the air in the air chamber 6 is compressed and flows out of the air chamber through the passage 8 in the guide 7. At this time, due to the airflow flowing through the passage 8, lift L and drag D are generated on the turbine blade 4 having a symmetrical blade shape, as shown in FIG. The lift and the drag are the turbine blade 4
The force acting in the chord length direction and the force acting in the direction perpendicular to the chord force act separately, and the resultant force of the blade force in the chord length direction acts to rotate the turbine. Here, α is the angle of attack, and represents the angle formed by the air flow and the blade.

On the other hand, when the sea surface in the air chamber 6 descends as shown by the arrow B in the figure, the pressure in the air chamber 6 becomes lower than the pressure in the outside thereof, so that the outside air passes through the passage 8 It will flow into the room. The direction of the flow is opposite to that when the sea level rises, but since the blade airfoil is symmetrical, the direction of the force acting in the chord direction of the blade is
It is constant regardless of the direction of the air flow, and only a force perpendicular to the chord length direction changes that direction. therefore,
Since the rotation direction of the working fluid is always constant with respect to the reciprocating flow, it can be said that it is a turbine particularly suitable for wave power generation.In particular, the biplane Wells turbine has improved start-up characteristics and stall margin compared to a normal Wells turbine. It has attracted attention because it is excellent in that it can improve the durability of bearings and bearings, and can reduce the speed of turbines that reduce noise.

(Problems to be Solved by the Invention) However, the efficiency of the conventional biplane wells turbine is lower than that of an ordinary wells turbine, and development of a turbine capable of overcoming this drawback is desired.

It is an object of the present invention to develop a symmetric blade type biplane turbine having the advantages of the conventional biplane type Wells turbine and having high efficiency, and to significantly improve the power generation efficiency of the wave power generation device.

(Means for Solving the Problem) In order to achieve this object, a wave power generation device using a birefringent turbine of the present invention crosses the axis of a rotor hub fixed to an output shaft at equal intervals around the rotor hub. Thus, in a wave power generation device using a symmetrical blade type Wells turbine in which a plurality of symmetrical blade type turbine blades fixed at one end are coaxially arranged in two rows, the two rows of symmetrical blade type turbine blades are A power generation unit that incorporates a symmetrical blade-type biplane Wells turbine and a generator that are symmetrically arranged with mounting angles α of 2 to 4 ° so that the trailing edges face each other, an air chamber that converts vertical movement of waves into air pressure, And a guide for guiding the airflow generated by this conversion to the outside of the wave power generation device or the inside of the air chamber according to the vertical movement of the wave, and In wave power generation apparatus using the symmetric airfoil biplane formula Wells turbine having a mounting angle, characterized in that disposed in the passage.

(Action) A lift and a drag force are generated in the turbine blade by the flow of the working fluid acting on the turbine blade, and the components of the forces acting in the chord length direction of the turbine blade rotate the turbine around the axis of the output shaft. It works. At this time, by using the birefringent turbine having the symmetrical blade type of the present invention, the two rows of turbine blades are provided with mounting angles so that their trailing edges face each other. It is possible to improve the starting characteristic and the average efficiency.

(Embodiment) A preferred embodiment of a wave power generation device using a symmetrical blade type birefringent Wells turbine having a mounting angle according to the present invention will be described in detail below with reference to the drawings.

1 (a) and 1 (b) are views showing an embodiment of a symmetrical blade type biplane wells turbine of the present invention. For the sake of simplicity, the fourth
The same reference numerals are given to the portions corresponding to the conventional example shown in FIGS.

The one shown in FIG. 1 is one in which the present invention is applied to a four-blade turbine.

In FIGS. 1 (a) and 1 (b), a biplane turbine 1 has two rotor hubs 3 fixed to an output shaft 2 so as to be spaced apart from each other in parallel with each other, and a plurality of turbine blades 4 are arranged around the rotor hub 3. 3 are arranged so as to be coaxially aligned in two rows in a direction intersecting the axial direction of 3.

The turbine blade 4 is formed with a mounting angle γ so that adjacent blades have their trailing edges facing each other. The effect of the mounting angle γ will be described in detail in the experimental example described later.

In this embodiment, two rotor hubs 3 parallel to each other are used.
The output shaft 2 is integrally fixed to the
The rotor hub 3 may be one integrally formed as shown in FIG. 1 (c).

FIG. 2 shows an example of a wave power generation device to which the biplane turbine of the present invention is applied.

In FIG. 2, the wave power generation device 5 has an air chamber 6 that converts vertical movement of waves into air pressure, and a guide 7 that guides an air flow generated by this conversion to the outside or the inside of the air chamber. A power generation unit 9 having a built-in power generator is arranged so as to form an air passage 8 inside 7, and the turbine 1 is connected to the power generation unit 9 via an output shaft (not shown).

Next, the operation of this power generator and turbine will be described.

For example, when the sea surface in the air chamber 6 rises as shown by an arrow A in the figure, the air in the air chamber 6 is compressed and flows through the passage 8 in the guide 7 to the outside of the air chamber. At this time, due to the airflow flowing through the passage 8, lift L and drag D are generated in the symmetrical blade type turbine blade 4, as shown in FIG. These lift force and drag force are divided into a tangential force of the turbine 1, that is, a rotation direction force and a force in a direction perpendicular to this force, and act on the tangential force of the turbine between the lift force L and the drag force D. The resultant force acts to rotate the turbine. On the other hand, when the sea surface in the air chamber 6 descends as shown by the arrow B in the figure, the pressure in the air chamber 6 becomes lower than the pressure in the outside thereof, so that the outside air passes through the passage 8 It will flow into the room. The direction of the flow is opposite to that when the sea level rises, but since the blade airfoil is symmetrical and the mounting angle is also symmetrical, the direction of the force acting in the chord direction of the blade is It is constant regardless of the direction of flow, so that the turbine always rotates in a constant direction.

Here, α represents the angle of attack, represents the angle formed by the air flow and the blade, and γ represents the mounting angle. In the birefringent turbine of the present invention, by providing the mounting angle, the conventional example shown in FIG. The combined force of the lift force L and the drag force D in the tangential direction of the turbine 1 is increased and the resultant force in the direction perpendicular to the increased force is reduced as compared with the turbine of FIG. Since the thrust force acting on the turbine can be reduced, the durability of the turbine bearing can also be improved.

Furthermore, in general, the wing performance has a characteristic that the lift increases with an increase in the attack angle α, and when it exceeds the maximum value, it suddenly decreases, and the drag force does not change so much in the range where the attack angle α is small. It has the characteristic of increasing sharply from the vicinity of the maximum value of.

Therefore, in the initial stage of starting the turbine having a particularly large angle of attack, providing the mounting angle in the direction of decreasing the angle of attack α increases the lift force L and decreases the drag force D, so that the starting characteristic of the turbine can be improved.

Note that the above is the effect on the turbine blade on the air inflow side, and the effect opposite to this occurs on the turbine blade on the air outflow side, but the effect on the output and starting characteristics of the turbine is to the inflow air. The turbine blade on the air inflow side without turbulence is larger, and the turbine blade on the air outflow side has turbulence in the air, and the turbine blade on the inflow side changes the direction of the air flow to some extent. Has little effect on.

Next, the symmetrical blade type birefringent Wells turbine of the present invention will be described in more detail based on experimental examples.

In the experimental example, the turbine under test was installed in a special wind tunnel where a reciprocating flow with an arbitrary waveform can be obtained by driving the piston with microcomputer control, and the turbine speed at a constant flow velocity section with a rectangular waveform and a sinusoidal flow velocity. Was kept constant and the turbine characteristics were obtained. Regarding the test rotor, various types shown in Table 1 were used in order to investigate the influence of the chordal ratio, the rotor interval, the blade mounting angle, and the rotor blade arrangement on the turbine characteristics.

As shown in Figs. 4 (a) and 4 (b), the turbines used in the experiment were arranged so that the blade edges of symmetrical blades (chord length l) face each other (mounting angle γ) and the distance G ( The center of the blade stack is located at 35% of the chord length from the leading edge, and the two blades are arranged in two rows at an axial distance of the stack center. Fourth
Figure (a) shows the case where the blade arrangement is plane symmetric, and this is shown as the blade arrangement (A).
And Fig. 4 (b) shows a staggered arrangement of blades, which is referred to as blade arrangement (B).

Figures 5 (a) and 5 (b) show the torque coefficient G and the total pressure coefficient P ^* obtained in the steady-state experiment for the symmetrical blade type birefringent Wells turbine of the blade arrangement (A) as the relative inflow angle at the blade average height. _{^{tan -1 (v a / U a}} ) {v a: mean axial velocity, _{U R:} are those indicated for the peripheral speed) in the wing average height, 6
The figure shows the average efficiency obtained in sinusoidal air flow as V _a / U _R (V
_a : the maximum value of V _a ). _CT ,
P ^* and P ^* are respectively defined by the following equations.

_{C T = T / {ρ (} v a 2 + U R 2) blZR / 2} P * = ΔP / (4ρω 2 R 2) Where T: output torque, ρ: air density, b: blade height, Z: blade coefficient, R: average radius, Δp: difference between stagnation chamber total pressure and atmospheric pressure, ω:
Rotor angular velocity, f: wave frequency, C _o : output, C _i : input.

In FIG. 5 (a), the relative inflow angle ^{_{tan -1 (v a / U R}} ) ≒ 20
The larger the value of the torque coefficient C _T after the stall point of ° is, the better the starting characteristic is. Therefore, in the turbine of the experimental example, the starting characteristic is that the mounting angle γ = 0 when the mounting angle γ = 2 ° to 4 °.
The result was better than that of the conventional bi-leaf type Wells turbine with a rotation angle of 0 °.

Further, it can be seen that the total pressure coefficient P ^* does not depend so much on the mounting angle γ except near the stall relative inflow angle.

FIG. 6 shows the effect of the mounting angle γ on the average efficiency, and V _a / U _R shows the maximum value of the average axial flow velocity / the peripheral velocity at the average radius. From the figure, the maximum value of average efficiency is obtained when the mounting angle γ = 4 °, which is larger than that of the conventional biplane wells turbine (γ = 0 °), and the ratio of the maximum values of both is _m4 / _m0 = 1.13.

However, the value of V _a / U _R indicating the maximum efficiency point decreases with the installation angle γ, and it is preferable that the installation angle γ be small from the viewpoint of reducing the turbine speed, and the installation angle γ = 2 in general. -4 ° may be suitable.

Fig. 7 shows the average efficiency and V _a / U in the case of the blade arrangement (B).
The relationship with _R is shown for the case of the blade arrangement (B). As shown in FIG. 7, the value of V _a / U _R at which the efficiency decreases contrary to the case of the blade arrangement (A) increases with the mounting angle γ, but in this case also γ = 2 ° to 4 ° is suitable as the mounting angle. It can be seen that it is. The maximum average efficiency of the blade arrangement (A) is larger than that of the blade arrangement (A), and the efficiency decreases V
_{The a} / U _R is larger in the wing arrangement (B). Such a wing arrangement (A)
The difference in the characteristics between the blade array and the blade array (B) is that the rotor of the blade array (B), which has a discrepancy, has an equivalently large chord-node ratio and the upstream rotor wake interferes with the downstream rotor. It is thought to occur.

From the results of the above experiments, the symmetrical blade type birefringent Wells turbine of the present invention has an installation angle of γ = 2 ° for both blade arrays (A) and (B).
It has been clarified that a higher output can be expected when compared with the conventional bi-leaf turbine (γ = 0 °) when set to 4 °.

(Effects of the Invention) As described in detail above, the symmetrical blade type birefringent Wells turbine for wave power generation having the mounting angle of the present invention has a plurality of turbine blades coaxially arranged in two rows so that their trailing edges face each other. By arranging the mounting angles symmetrically with each other, it is possible to remarkably improve the starting characteristics and the average efficiency while taking advantage of the speed reduction of the turbine in the conventional biplane wells turbine in which the mounting angles are not provided. It is possible to realize a wave power generation device with high output even though the turbine bearing has high durability and low noise.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing an embodiment of a symmetrical blade type birefringent Wells turbine for wave power generation having a mounting angle of the present invention, and FIG. 1 (b) is a turbine of FIG. 1 (a). Partially cutaway side view, FIG. 1 (c) is a partially cutaway side view showing another embodiment of the symmetrical blade type biplane wells turbine of the present invention, and FIG. 2 is a symmetrical blade type biplane of the present invention. Sectional view showing an example of a wave power generator using a wells turbine, Fig. 3 is a view showing the action of a symmetrical blade type biplane wells turbine of the present invention, and Figs. 4 (a) and 4 (b) are respectively The figure which shows an example of the blade arrangement | sequence used for the symmetrical blade type birefringent type Wells turbine of FIG. The torque coefficient G and the total pressure coefficient P ^* are expressed as the relative inflow angle tan at the blade average height.
^-1 (v a _/ U _R) diagram showing respect, Figure 6 is an average efficiency obtained by a sine wave in a stream in a symmetric airfoil biplane formula Wells turbine V _{a /} U blading (A) _R
Fig. 7 is a diagram showing the relationship between the average efficiency and V _a / U _R in the symmetrical blade type biplane wells turbine of the blade arrangement (B), and Fig. 8 is a conventional biplane FIG. 9 is a perspective view showing a conventional wells turbine, FIG. 9 is a sectional view showing an example of a wave power generation device using a conventional double leaf wells turbine, and FIG. 10 is a view showing an operation of the conventional double leaf wells turbine. 1 ... Turbine, 2 ... Output shaft 3 ... Rotor hub, 4 ... Turbine blade 5 ... Wave power generator, 6 ... Air chamber 7 ... Guide, 8 ... Air passage 9 ... Power generation unit

Claims (1)

[Claims] 1. A symmetry comprising a plurality of symmetrical blade type turbine blades coaxially arranged in two rows around a rotor hub fixed to an output shaft so as to intersect the axis of the rotor hub at equal intervals. In a wave power generation device using a blade-type wells turbine, a symmetrical blade-type biplane wells in which the two rows of symmetrical blade-type turbine blades are symmetrically arranged with a mounting angle α of 2 to 4 ° so that their trailing edges face each other. A power generation unit with a built-in turbine and a generator, an air chamber that converts vertical movement of waves into air pressure, and an air flow generated by this conversion outside the wave power generation device or inside the air chamber depending on the vertical movement of the waves. A symmetric blade type birefringent wells turbine having a mounting angle is provided, in which a guide for guiding to the power generation unit is provided in an air passage formed in the guide. Power generation equipment.