WIND WHEEL IN MOTION

WINDMILLS, WIND and WORK

Thomas O. Perry experiments with American Mills:

1.         The maximum power which may be obtained from a given windwheel  varies directly as the cube of the wind velocity  .

2.         The sail speed of a windwheel, when developing its maximum power, varies directly as the wind velocity.

3.         The load upon a windwheel, when developing its maximum power, varies directly as the square of the wind velocity.

4.         The capacity of a windwheel varies directly as the square of its diameter.

5.         The number of turns a windmill will make in a given time varies inversely as its diameter.

6.         There is nothing gained by having the sail area of a windwheel  greater than seven-eights of the area swept by the sails, and there is little gained by having it more than three-fourths.

In order that the maximum power may be obtained from a windmill, in winds of varying velocity, the load must vary directly as the square of the velocity.  A pumping mill load is practically constant during a complete cycle.  The load varies from about zero during one stroke to a maximum at about the middle of the other stroke.  This is a source of loss especially when the windwheel is rotating slowly.

NOTES ON LOAD COMPENSATION

Counter balance methods may be used for the lifting elements, from the connecting rods to the pump piston.  This may be considerable for deeper wells when using metal sucker rod. The water-pumped ratio to water-load lifted could be improved as the stroke is lengthened and the column diameter is reduced.

The dead weight of the water column, at the end of discharge, cannot be used to aid the down stroke!

A conversion of the bucket to a force pump would allow for a smaller discharge pipe and an improved water to work ratio as the lifting column would be moving the equivalent volume in longer pulses while lifting  less weight.  The  discharge pipe could be external or the hollow sucker rod could be used. 

Counter balancing could be a balance weight, springs to aid the up stroke, or buoyant  donuts added to the sucker rod,  These would aid the lift and displace water in the column.

1-15-93     nw

Servicing a Champion Mill

WIND STRENGTH BEAUFORT SCALE

FORCE                       AIR  MOVEMENT                   WIND SPEED

                                                                                                          Meters/Sec.

0-2   Light Breeze                    Leaves rustle                                        0-3

3-4   Moderate Breeze            Leaves, twigs, small ranches move       4-7                     

5-6   Fresh to strong Breeze    Small leafy branches make swaying    8-12

                                                 movements    crested waves   

6      Strong Breeze               Big branches move, Telegraph wires whistle, larger waves, foam patches  

7      Moderate gale                    Whole trees move, hard to walk         12-15

8      Twigs break off,                  we strain against the storm.               13-15

8+     gale force                           roofs and chimneys damaged             

         At 12-13   M/S                    Mill must be stopped

Note:     Aermotor  16’     .601 HP @ less than  25 m/h wind.

              Eclipse      22.5’  .182 HP @  “      “       “     “      “

              Large Polder mill,    1750-200 cu’/min  Cap 50,000 KWH/ year

              Stock Mill                 75-95’     “     “       “

Output proportional to cube of windspeed

Capacity proportional to square length of sail.

86’ span at 66 enden equals 55 HP average.

nw

HYDR0STATIC PARADOX

The following paragraph is from Audel Pumps by Harry L. Stewart.

When water is placed in containers having different shapes  (Flask, Beaker, Funnel, or tall thin and short and wide), the intensity of the pressure, in lb.per square in., is the same at the bottom of each container, but the total liquid pressure against the bottom of each container is proportional to the area of the bottom of the container.  This is related to the hydraulic principle that:  A small quantity of fluid can be made to balance a much larger weight.

The quantity of liquid, or its total weight, has no effect either on the intensity of pressure or the total pressure, if the head remains the same.  The fact that the total liquid pressure against the bottom of the vessel may be many times greater,

(Or many times less) than the total weight of the liquid is termed a HYDROSTATIC PARADOX.      (NOT TO BE CONUSED WITH - - - - - - - - - - - --

Hydrostatic Balance:

A body immersed in a liquid loses an amount of weight that is equivalent to the weight of the fluid displaced.

(That is why objects float!)

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Here I wrote my explanation to my tenant George Champion in March 1999.