目录
Introduction to Pelton Wheel or Turbine :
- 涡轮机的旋转动力学亚组用于利用将液压能转化为机械能的能力。根据他们的规格，它们具有不同的类型。涡轮机可以分为两组，冲动和反应涡轮机。此外，由于使用的工作流体，涡轮机可以称为蒸汽轮机，燃气轮机，风力涡轮机和水轮机。
- Pelton wheel, named after an eminent engineer, is an impulse turbine wherein the flow is tangential to the runner and the available energy at the entrance is completely kinetic energy.
- Pelton wheel is preferred at a very high head and low discharges with low specific speeds.入口和出口处可用的压力是大气的。
- 这种类型的涡轮机是1889年由洛杉矶Pelton开发和专利的，所有类型的涡轮机被他的名字称为纪念
him.
Parts of Pelton Turbine :
The main components of a Pelton turbine are:
- Nozzle and Flow Regulating Arrangement
- Runner with Buckets
- Casing
- 打破喷气机。
1. Nozzle and flow regulating arrangement :
- Water is brought to the hydroelectric plant site through large penstocks at the end of which there will be a nozzle, which converts the pressure energy completely into kinetic energy. This will convert the liquid flow into a high-speed which strikes the buckets or vanes mounted on the runner, which in turn rotates the runner of the turbine.
- The amount of water striking the vanes is controlled by the forward and backward motion of the spear.
- 长矛是圆锥形针，由手轮操作或自动在轴向方向上操作，具体取决于单元的大小。
- 将长矛向前推入喷嘴时，撞击跑步者的水量减少。另一方面，如果将长矛向后推，那么击中跑步者的水量就会增加。
2. Runner with Buckets :
- 跑步者是安装在外围轴上的圆盘，该轴的轴固定在外围的轴上，几个桶的固定固定为固定，如图2所示。
- 这些水桶由铸件铸造，青铜或不锈钢制成，具体取决于涡轮机入口的头部。
- The shape of the bucket is of a double hemispherical cup or bowl. Each bucket is divided into two symmetrical parts by a dividing wall which is known as the splitter.
- 水的喷射在分离器上罢工。分离器将喷气机分为两个相等的部分，并且射流位于水桶的外边缘。
- The water jet strikes the bucket on the splitter of the bucket and
gets deflected through (α) 160-170°. - 喷气机的布置 -在大多数佩尔顿轮植物中，都使用具有水平轴的单个射流。所采用的喷气机的数量取决于所需的特定速度。
3. Casing :
- It is made of cast -iron or fabricated steel plates. The main function of the casing is to prevent the splashing of water and to discharge the water into the tailrace.
- Casing is also acting as a safeguard against accidents.
- It is made of cast iron or fabricated steel plates. The casing of the Pelton wheel does not perform any hydraulic function.
4. Breaking jet:
- 即使在撞击水桶的水量完全停止之后，由于
在ertia. - To stop the runner in a short time, a small nozzle is provided which directs the jet of water on the back of the bucket with which the rotation of the runner is reversed. This jet is called as breaking jet.
5. Governing mechanism:
- The speed of the turbine runner is required to be maintained constant so that the electric generator can be coupled directly to the turbine. Therefore, a device called governor is used to measure and regulate the speed of the turbine runner.
Working of Pelton wheel:
- 将储存在高头部的水流流过骨头，并到达佩尔顿涡轮机的喷嘴。
- The nozzle increases the K.E. of the water and directs the water in the form of a jet.
- 喷嘴的水喷射撞击了跑步者的水桶（叶片）。这使跑步者以非常高的速度旋转。
- The quantity of water striking the vanes or buckets is controlled by the needle valve present inside the nozzle.
- 发电机连接到跑步者的轴上，将跑步者的机械能转换为电能。
佩尔顿轮的速度三角图：
- The jet of water from the nozzle strikes the bucket at the splitter, which splits up the jet into two parts. These parts of the jet glides over the inner surfaces and comes out at the outer edge.
- The splitter is the inlet tip and the outer edge of the bucket is the outlet tip of the bucket.
- The inlet velocity triangle is drawn at the splitter and the outer velocity triangle is drawn at the outer edge of the bucket.
Where,
V1 =入口射流的速度
U1 =入口处的叶片/水桶的速度
VR1 =射流的相对速度
α=喷射的方向和角度direction of motion of the vane, guide blade angle (Here in this figure it is zero)
θ = angle made by vr1 with the direction of motion of vane at the inlet, vane angle at inlet (=0)
vw2 =出口处旋转的速度
Vf2 = velocity of flow at the outlet
β= V2之间的角度与叶片在出口处的运动方向
ϕ =由VR2与叶片在出口处的运动方向，叶片角度在出口处的叶片方向
佩尔顿轮 - 效率和工作
（i）喷气机上的跑步者每秒完成的工作
（ii）每秒每单位重量击打= 1/g（vw1 + vw2） *u
(iii) Hydraulic efficiency,
（iv）机械效率=shaft power / Bucket Power
(v) Volumetric efficiency, =实际上击中了跑步者 /总水的水数量
(vi) Overall efficiency, =轴电 /水力= P /ρGQH
Design Of Pelton Wheel :
1.入口v1 =cv√2GH….. cv =速度系数= 0.98-0.99
2. Velocity of wheel where u = φ √2gH ………..Where φ is the speed ratio = 0.43-0.48
3. The angle of deflection is 165° unless mentioned.
4. Pitch or mean diameter D can be expressed by, u= πDN / 60
5.喷气比M = D/D（大多数情况下为12个/D），D =喷嘴直径
6. Number of bucket on a runner Z = 15 + D/2d = 15 + 0·5 m
7.喷气机数量=通过将通过涡轮机的总流量除以通过单射流的流量
8.铲斗大小：轴向宽度，径向长度，深度
佩尔顿涡轮机的性能和操作特性曲线：
The followings are the important characteristic curves of a turbine :
Main Characteristic Curves or Constant Head Curve –
The speed of the turbine is varied by changing the load on the turbine. For each value of the speed, the corresponding values of the power (P) and discharge (Q) are obtained.
操作特征曲线或恒定速度曲线
- Tests are performed at a constant speed.
- Constant speed is attained by regulating the gate opening thereby varying the discharge flowing through the turbine as the load varies.
- 头可能会或可能不会保持恒定。
Advantages of Pelton turbine
- 它有简单的结构
- It is easy to maintain
- Intake and exhaust of water takes place at atmospheric pressure hence no draft tube is required
- 没有空气问题
- 它的总体效率很高
- It can be both axial and radial flow
- It can work on low discharge
Disadvantages of Pelton turbine
- 它需要高头操作
- 涡轮尺寸通常很大
- Its efficiency decreases quickly with time
- 由于头部高，很难控制操作头的变化
佩尔顿轮的应用：
- Pelton wheels are the preferred turbine for hydro-power when the available water source has a relatively high hydraulic head at low flow rates.
- Pelton wheels are made in all sizes. For maximum power and efficiency, the wheel and turbine system is designed such that the water jet velocity is twice the velocity of the rotating buckets.
- There exist in multi-ton Pelton wheels mounted on vertical oil pad bearing in hydroelectric power.
See also :弗朗西斯涡轮机 - 图，工作，零件，优势，应用
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