JP2006132383A - Vertical shaft pelton turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase operation specific speed by suppressing interference of adjoining jets in a vertical shaft Pelton turbine using two steel penstocks. <P>SOLUTION: In the vertical shaft Pelton injecting jet 12 to a bucket 11 through a plurality of branch pipes 3-8 branching out of the two steel penstocks 1, 2, the branch pipes 3-8 are constructed with bent pipes including a bend 13 right front of a nozzle and bend directions of all branch pipes 3-8 are made same as a rotation direction of the runner 10. Consequently, since flare 12f of the jet 12 formed inside of bends of branch pipes 3-8 is oriented to an inner circumference side of all buckets 11 and interference of jets are suppressed, high specific speed at an operation point can be achieved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a Pelton turbine, and more particularly to an upright Pelton turbine that branches a branch pipe from two pieces of hydraulic iron pipe.

As is well known, a Pelton turbine rotates a runner by jets injected into a bucket through a plurality of branch pipes branched from a hydraulic iron pipe. The horizontal axis is a single-shot type, two-shot type, the vertical axis is a four-shot type, and a five-shot type. The six-shot type is often used. The horizontal axis Pelton turbine is described in, for example, Patent Document 1, and the vertical axis Pelton turbine is described in, for example, Patent Document 2.
JP-A-8-218999 JP-A-8-151973

  By the way, there are generally one hydraulic iron pipe that guides the water of a dam to a Pelton turbine. In the case of collecting water from a single vertical Pelton turbine, there are cases in which two hydraulic iron pipes exist for one Pelton turbine.

  FIG. 2 shows the shape of a conventional branch pipe in a vertical-axis six-shot Pelton turbine having two hydraulic iron pipes. In FIG. 2, three branch pipes 3 to 5 and 6 to 8 respectively branch from two hydraulic iron pipes 1 and 2, and a jet 12 is jetted from a nozzle 9 at each end to a bucket 11 of a runner 10, The runner 10 rotates in the direction of the arrow. Since the interval between the two hydraulic iron pipes 1 and 2 is wide, the branch pipes 3 to 5 and 6 to 8 have a so-called foot shape as shown in the figure, and the branch pipes 3 and 7 are straight pipes and branch pipes. 4, 5, 6, and 8 are curved pipes having a bend 13 immediately before the nozzle.

  FIG. 3 is a side view conceptually showing a jet from a branch pipe having a bend just before the nozzle. As shown in FIG. 3, flare (splash water) 12f is usually generated inside the branch pipe bending direction in the jet 12 ejected from the nozzle 9 of the branch pipe having the bend 13 upstream. This is presumably because the pressure of the nozzle portion is high at the outside of the curve and low at the inside of the curve.

On the other hand, when the six-shot Pelton turbine is at a high specific speed, jet interference tends to occur. The specific speed n _S is given by the following equation.
n _S = n · P ^1/2 / H ^5/4

Here, n is the turbine speed (min ⁻¹ ), P is the turbine output (kW), and H is the effective head (m). As can be seen from this equation, when the effective head is assumed to be the same, the rotational speed is high or the turbine output, that is, the turbine flow rate is large when the specific speed is high.

  A six-shot Pelton turbine is jetted from nozzles arranged every 60 degrees and flows into the bucket. The change in the relationship between the bucket and the jet in that case is shown in FIGS. In FIG. 4, for example, when the first jet 12 (1) flows into the bucket 11 (1) indicated by a thick line and then starts to flow into the subsequent bucket 11 (2), between the buckets 11 (1) and 11 (2). Since there is a gap, water 12 (1) a (shaded portion) in flight exists in the gap. On the other hand, the bucket 11 (1) rotates at a speed almost half of the jet flow velocity, and the water 12 (1) a existing in the gap gradually flows into the bucket 11 (1) (see FIG. 4B). .

  At that time, if the second jet 12 (2) starts to flow into the bucket 11 (1) before the water 12 (1) a finishes flowing into the bucket 11 (1), the adjacent jets 12 (1), 12 (2) They interfere with each other (see FIG. 4C), and the turbine efficiency is drastically reduced. Therefore, in the six-shot Pelton turbine, it is necessary to select an operation point (specific speed) so that such jet interference does not occur. When the specific speed is high, the runner rotation speed is high or the jet diameter is large (the flow rate is large) even if the gap between the buckets is the same, so that the inflow end point of the first jet 12 (1) is the second jet 12 (2 ) Approaches the inflow start point, and jet interference easily occurs.

  In that case, if the flare 12f (see FIG. 3) of the jet 12 exists so as to be scattered on the outer peripheral side of the bucket, in FIG. 4, the inflow end point of the first jet 12 (1) to the bucket 11 (1) is delayed. Since it approaches the inflow start point of the second jet 12 (2), jet interference is more likely to occur.

  However, the conventional crab-like branch pipe shape shown in FIG. 2 has a flare 12 f that extends toward the bucket outer periphery in the branch pipes 4, 5, and 6. For this reason, jet interference is likely to occur, and as a result, only an operating range in which the hydraulic iron pipe has a specific speed lower than that of a normal vertical shaft water turbine having one line can be selected.

  Accordingly, an object of the present invention is to increase an operation specific speed by suppressing interference between adjacent jets in a vertical shaft Pelton turbine using two hydraulic iron pipes.

  In order to solve the above-mentioned problems, the present invention provides a vertical pelton in which a jet is injected into a bucket through a plurality of branch pipes branched from two hydraulic iron pipes. It is configured by a pipe, and the bending direction of all the branch pipes is the same as the rotation direction of the runner (Claim 1).

  In the invention of claim 1, the two hydraulic iron pipes are arranged parallel to each other on both sides of the runner, the ends of the hydraulic iron pipes are bent alternately toward the runner, The branch pipes may be connected point-symmetrically with respect to the center of the runner (claim 2).

  According to this invention, by making the bending direction of all the branch pipes the same as the rotation direction of the runner, the flare of the jet injected from each branch pipe is prevented from scattering to the outer peripheral side of the bucket. Even when a hydraulic iron pipe is used, a reduction in the operation specific speed can be avoided.

  FIG. 1 is a plan view showing a branch pipe shape of a six-shot vertical shaft Pelton turbine according to an embodiment of the present invention. In addition, the same code | symbol shall be used for the part corresponding to a prior art example. In FIG. 1, two hydraulic iron pipes 1 and 2 are arranged in parallel on both sides of the runner 10, and the ends 1 a and 2 a of these hydraulic iron pipes 1 and 2 are bent at right angles toward the runner 10 alternately. . The three branch pipes 3 to 5 and 6 to 8 are connected to the ends 1 a and 2 a of the hydraulic iron pipes 1 and 2 in a point-symmetric manner with respect to the center of the runner 10. Here, each branch pipe 3-8 is comprised by the curved pipe which has the curve 13 just before the nozzle 9, and all the bending directions of these branch pipes 3-8 are made the same as the rotation direction of the runner 10 shown by the arrow. Yes.

  In the illustrated water wheel, all of the flare 12f of the jet 12 generated inside the bends of the branch pipes 3 to 8 is directed to the inner peripheral side of the bucket 11. As a result, the flare 12f does not scatter to the outer peripheral side and cause jet interference, so that the specific speed of the operating point can be increased. Moreover, in the case of illustration, since the three branch pipes 3-5 and 6-8 are respectively connected point-symmetrically with respect to the center of the runner 10, the loss of the branch pipes facing each other across the runner 10 is lost. As a result, the jet flow velocities are also equal. As a result, there is an advantage that the balance of the component (radial thrust) in the runner radial direction of the driving force acting on the runner 10 from the jet becomes good. In the illustrated embodiment, an example of a six-shot vertical-axis Pelton turbine has been described. However, the present invention can be similarly applied to a five-shot or four-shoot vertical Pelton turbine.

It is a top view which shows the branch pipe shape of the 6 shot type | formula vertical shaft Pelton turbine which shows embodiment of this invention. It is a top view which shows the branch pipe shape of the 6 shot type | formula vertical shaft Pelton turbine which shows a prior art example. It is a side view which shows the jet from the branch pipe which has a curve just before a nozzle. It is a principal part top view which shows the change of the relationship between the bucket and jet of a six-shot type vertical axis Pelton turbine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic iron pipe 2 Hydraulic iron pipe 3-8 Branch pipe 9 Nozzle 10 Runner 11 Bucket 12 Jet 12f Flare 13 Bend of branch pipe

Claims (2)

In the vertical axis Pelton in which a jet is injected into a bucket through a plurality of branch pipes branched from two hydraulic iron pipes,
A vertical shaft Pelton turbine characterized in that the plurality of branch pipes are formed of curved pipes having a bend in front of a nozzle, and the bending directions of all the branch pipes are the same as the rotation direction of the runner. The two hydraulic iron pipes are arranged in parallel to each other on both sides of the runner, the ends of the hydraulic iron pipes are bent alternately toward the runner, and a plurality of the branch pipes are arranged at the ends of the center of the runner. The vertical shaft Pelton turbine according to claim 1, wherein the vertical shaft Pelton turbines are connected point-symmetrically to each other.

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