风力机的工作原理----活塞水泵

           

How a Windmill Works - Cylinder Pumps

A windmill is one of the most energy efficient and ingenious ways ever devised to pump water from the ground. A windmill harnesses the free and renewable power of the wind and uses that energy to lift underground water to the surface for agricultural and other uses.

           Because windmills are so efficient and durable, the basic design hasn't changed in almost 120 years. The secret lies in the way a windmill harnesses the wind's energy to power a n ingenious water pump located deep underground.

Windmill

           The power of the wind is captured and harnessed in two steps. Each step is easy to identify by simply observing a windmill in action.

First, notice how the fan turns. A windmill captures the energy of the wind with the large, circular fan, or "wheel", located at the top of the tower. When the wind blows, the fan rotates. This turning (rotary) motion is so commonplace that it's easily taken for granted. But don't. This is where the free energy of the wind is captured.

Second,look just below the turning wheel and notice a long rod moving up and down. This "sucker rod", is powered by the windmill's motor. This motor is a unique set of mechanical gears that converts the rotary motion of the wheel into a reciprocating (up and down) motion that powers the cylinder pump located deep underground.

Groundwater

Water trapped in an underground, water-bearing formation is called an aquifer. The top of an aquifer is called the "water table". The depth of this water table is important because it determines how deep a water well must be drilled. It also determines the size of the windmill required to pump water to the surface.

A water well is a small-diameter hole drilled into the earth's crust that fills up with water. As the well is drilled, it passes through various underground layers of sand and gravel, and extends into an aquifer, or underground water-bearing formation.

Once the well is drilled to the proper depth, the well wall is reinforced and perforated to allow water from the surrounding aquifer to seep into the well. Gravity causes the water to rise to the level of the underground water table.

A sealed "drop pipe" is then inserted into the well until its lower end is fully immersed in the well water.

Cylinder Pump

The cylinder pump operates in a very ingenious way. It doesn't use high-powered suction. Instead, it builds a "column of water" from the aquifer to the surface within the drop pipe... from the bottom upward.

The cylinder pump accomplishes this feat by creating a one-way flow of water within the drop pipe and constantly ratcheting water upward.

Two specialized pump valves work together to draw well water into the bottom of the drop pipe and then ratchet the water column upward. By repeatedly adding water to the bottom of the water column, the drop pipe fills and water pours out the top into a storage tank.

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For a detailed look at a cylinder pump in action, continue to the animated cylinder pump illustration.

 

The cylinder pump is located inside the windmill's drop pipe near the bottom of the water well. It pumps water from the bottom of the well by ratcheting it upward through the drop pipe, towards the storage tank.

It achieves this by repeatedly drawing water in through the bottom of the drop pipe and lifting the water column upward. This cycle repeats until water pours out of the top of the drop pipe into the storage tank.

Cylinder Pump Valves

Two valves work together in an opposing manner to pump water. The top valve is called the "plunger" and the lower valve is called the "check valve". Power is provided by the windmill motor and transmitted to the plunger through the sucker rod.

Several Things Happen At Once ...

As you view the animated cylinder pump illustration keep several things in mind:

1. Water can only flow upward through the valves. It's strictly an upward, one-way flow of water.
2. Each valve has a watertight seal at its base. Water passes through the valve's bottom then up-and-out through the valve's side vents.
3. When a valve's ball is down, the valve is closed. When a valve's ball is up, the valve is open.
4. Only the plunger moves. The plunger's seal is watertight in the drop pipe. But as it slides up and down, the plunger creates a pumping action.
5. The lower check valve is fixed in position. Water enters through the strainer and flows upward through the check valve.
6. When the wind stops blowing, both valves close and pumping stops, The water column above the plunger and the "cylinder water" trapped between the two valves are held in place, ready for the pumping to resume when the wind begins to blow again.
7. Ball Valves in Action

8. The ball's orientation in the valve basket is the key.

   · When the ball is "up", the valve is open.
   · When the ball is "down", the valve is closed.

   Water Flows Upward

   Dark blue well water is drawn upward through the lower check valve, filling the cylinder pump.

   The sky blue water column water above the plunger is lifted upward.

   Pale blue water in the cylinder area becomes the new bottom of the water column as the plunger moves downward.

   Valves Work in Opposition to Each Other

   When the wind blows, the plunger moves up and down. As the plunger moves, each valve opens and closes at the appropriate time causing water to be pumped upward.

   

   Upstroke

   On the upstroke, plunger valve closes and the check valve opens. Water above the plunger (the water column) is lifted. This lifting motion also creates a vacuum between the plunger and the check valve. This vacuum opens the check valve, and well water flows up through the strainer into the drop pipe.

   Downstroke

   On the downstroke, plunger valve opens and the check valve closes. The plunger can then pass through the water being held "in check" by the lower check valve. This downstroke forms the new bottom of the water column.

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   View the animated windmill illustration to see everything in action.