US5090A - Improvement in diffusers for water-wheels - Google Patents

Description

NITED STATES PATENT OFFICE- URIAH ATHEETON BOYDEN, oF BosToN, MASSACHUSETTS.

iMPROVEMEN'l' IN DIFFUSERS FOR WATER-WHEELS.

Specification forming part of Letters Patent No. 5,090, dated May 1, 1847.

ciency of Vtater in Moving Wheels by Usingv a Diffuser; and I do hereby declare that the following is a full and exact description thereof.

The nature of my invention consists in causing the stream or streams of water from y a water-wheel to diverge gradually, or in caus ing the water which is ejected from a Watervvheel to be diffused gradually, whereby the momentum which the water has on leaving the water-wheel is expended in diminishing the pressure of the water or air on the parts of the wheel which the water last leaves, which is effected by applying a diverging or flaring passage or passages to the exits of the wheel, which passage or passages the water necessarily passes through after leaving the wheel, which causes the stream or streams of water to expand or spread gradually or to be gradually diffused, and hence I call this adjunct to the wheel which I have linvented a diffuser.

To enable others skilled in the art to make and use my invention, I will proceed to 'describe its construction and operation, beginning by describing the annexed drawings, which make a part of this specification, in which- Figure l is an isometrical projeotion'of the flume, a part of the water-wheel shaft, and the frame which supports them. In this View the water-wheel and the diffuser are hid by the parts above them. Fig. 2 is an elevation of the water-wheel, a part of its shaft, and the diffuser. Fig. 3 is a horizontal section of the water-wheel and its shaft, in which figure the .lower part of the diffuser is shown as it appears when looking down perpendicularly upon it. Fig. l is on a smaller scale than the other figures.

The same small letters in all the figures refer to the same parts.

h h, &c., Fig. l, is the frame which supports the flume, shaft, wheel, and diffuser.

f is the fiume. ,Y

w w w, Figs. 2 and 3, is the water-wheel. u

Water-wheels of the form represented bythe drawings are called turbines, or, rather,-y

a wheel of this form is a part of a hydraulic machine calledturbine, and a wheel of this kind has adisk within it which sustains the water in the flume, and there is an annular gate in the wheel, which gate rests on the said disk when it is not necessary to have the wheel in operation. The effects of the diffuser, which is the part or adjunct claimed,

.do not depend on the said disk or gate, nor

tral parts by either ascending or descending, vor by both, and out at their circumference, Whether their circumference represent the form of a Zone of a sphere, the frustum of a cone, or be cylindrical, or of any other form.

My diffuser consists principally of two annular parts, which, for convenience in describing,Iwillcallplatforms. The upper one dd d encompasses the upper part of the waterwheel, and the lower platform e e e encompasses the lower part of the water-wheel. The upper surface of the-lower platform next the wheel is at the same height 'as the bottoms of the apertures of the wheel through which the water escapes, or a very little lower than the bottoms of these apertures; 'and this part of the platform ts the wheel as closely as it is practicable to keep it without the wheel rubbing it so as to produce any considerable friction. This is made to fitclosely about the lower rim of the wheel to prevent any considerable quantity of water from ascending between it and the wheel. The lower surface of the upper platform next the wheel is of the same height asthe tops of the outlets of the wheel, or a very little higher than the tops of these outlets, and this part of the platform ts the upper rim, or the circumference of the upper ring of the wheel closely, to prevent the descent of the water between it and the wheel, but is not made to touch the wheel, so

as to produce any considerable friction. The upper surface of the lower platform is curved downward, the commencement of the curve next thewheel having the samedirection as the lower part of the stream or streams where the water passes out of the wheel-that is, the direction of the lower part of the stream where it first touches the upper surface of the lower platform is a t-an gent to this su rface, or the coml mencement of this surface next the wheel inclines downward so as to diverge a little from the said direction of the stream or streams in the direction from the wheel. The lower surface of the upper platform is curved upward, the commencement of the curve next the wheel having the same direction as the upper part of the stream or streams where the water passes out of the wheel; or the commencement of this surface next the wheel inclines upward so as to diverge a little from the direction of the said upper part of the stream or streams in the direction from the wheel. All parts of these two surfaces may be of the Same curvature.

The diameter of the diffuser is about double the diameter of the wheel, and the space between the outer edges of the two platforms is about twice as wide as the spacebetwzeen their inner edges next the wheel. With wheels as usually constructed the parts of the curved surfaces of the two platforms next the water-wheel may diverge a 1ittle-that is, the first element of the curve next the waterwheel of the upper platform may diverge a little from the first element of the curvenext the water-wheel of the lower platform inthe direction from the wheel. This angleof divergence may be about six degrees. y The circumference or outer extremity of the` lower surface of the upper platform should be as low or lower than the surface of the water about the wheel which has passed through the wheel or which is below the fall-that is, the outer extremity of the lower surface of the upper platform should be so low as to be always immersed in the tail-water when the wheel is working.

I have above described the particular form of my diffuser, which I think is best for the majority of cases; but some modifications of this form will answer better and be more conveniently applied in some cases, and there are some other modifications which will answer nearly as well as the form above de scribed. Instead of the lower platform being fitted very closely to the lower periphery of the water-wheel to prevent the ascent of water between the platform and the wheel, this may in some cases be conveniently effected, when there is a suitable floor or partition under the wheel, by closingA all passages between the lower platformand the floor or partition, so as to form a water-tight joint between them; and the descent of water or air between the upper platform and the waterwheel may be prevented Vby closing all passages between the upper platform and lfiume.

The surfaces of the diffuser which confine the stream or streams maybe somewhatdifferent from what I have above described and the diffuser still operate according to the same principle. Thus these surfaces may be curved dierently, or they'may be plain, or one may be plain and the other curved; but it is essential that they be such, or that the passage or passages formed by thediffuser be such, as to cause the stream or streams to expand or spread in one direction at least, and that this expansion or diusion be gradual or by successive degrees. If `the passage or passages be made to widen or diverge irregularly, or be made to widen or diverge by small steps or offsets, the diffuser thus formedv may cause the stream or streams to expand, and it will still operate, though imperfectly, except-ing when these irregularities, steps, or offsets are very small, so as to approximate to a gradual Haring or enlargement. Props may be placed between the two platforms to prevent theirbeing pressed toward each other when neither of the platforms is to be movable, and when this object cannot couvenientlybe effected by other means. These props should be thin andso placed as to ob# struct the flow of the water as little as practicable. One or both platforms, more particularly the upper one, may be movable,^so

Vthat the width of space between them may be varied and the quantity of water which passes through the Wheel thus regulated.

' This diffuser may beappliedto verticalor inclining reactingfwheels and vertical or inclining turbine wheels.

In some cases the wheel of a turbine has one or more diaphragms between the upper and lower rings of the wheel which the floats are fastened to. These diaphragms are aunular and of about the same width anddiameter as the width and-diameter of the rings of the wheel which the upper and lower edges of the oats are attached to, or the diaphragm is composed ofpieces'iixed between the floats, which pieces collectively form an annular partition in the wheel, as is well known to people conversant with this kind of waterwheels. For a turbine wheel which i has a diaphragm there shouldbe, in addition to the diffuser, as above described, an annnlarpartition between the platformsl of about the same diameter as that of the platforms. This annular partition should be at the height of the diaphragm in the wheel, and it should encompass" and fit as closely to the diaphragm as it can without touching it so as to produce any considerable friction. The inner part of this partition next the diaphragm should have the same thickness or be a very little thinner than the circumferential parts of the diaphragm next it. The circumferential parts of the partition should be as thiny as they can be and have sufficient strength and stiffness to resist the pressure of the water. If this partition havel not the same thickness at its circumference and at itsinner part next the dia phragm, the change of thickness should be gradual.

When there is more than one diaphragm in a wheel, there should be as many annulail partitions between the platforms as there are diaphragms, one partition to encompass each diaphragm, as above described for the case when there is only one.

Though it is best to havev the diffuser so shaped thatl the expanding or'diffusing of the stream or streams will commence at the exit or exits ofthe water-wheel, it will operate when it is so shaped that the expanding or diffusing is produced'only at a considerable distance from the wheel, as when the parts of the passage or passages which are at a considerable distance from the wheel are diverging or flaring and the other parts of the passage or passages which are near the wheel not diverging or flaring.

Where mywdiffuser is used, it is best to construct the turbines a little different from what they otherwise should be, as follows: vIncrease the length of the radii of the leading'curves a little through their whole length, so that while their inner ends next the axle of the wheel remain unaltered their outer ends have their directions changed three degrees. As the ends of the leading curves should be at the same distance from the axis of the Wheel after the change which they were before the change, their length must be diminished a little when this change of curvature is made. Take so much from the outer extremity of each float as forms three degrees of the curvature of each float, letting the outer ends of the remaining parts of each of the floats have the same directions which these parts had before the outer parts were removed. Diminish the curvature of all parts of the remaining parts` of each iioat in the same ratio, so as to change the directions of the inner ends of the floats five degrees each. Hence the whole deflection of each oat will be diminished by eight degrees. The inner ends of the iioats should remain at the same distance from the axis of the Wheel which they were before the alteration,and as this diminution of the curvature ot' the floats moves their inner-ends a little toward or from the axis of the wheel, according to the directions which these ends had before the alterations, the length of the iioats will be diminished moreor less than by the Whole quantity taken from their outer extremities, according to the directions which the inner ends of the floats had before the alterations; but the Whole diminution of curvature of each float should be eight degrees, as above stated. When the length of the floats is so diminished by taking off their outer parts, it is best to diminish the width of the rings of the wheel which the edges of the floats are fastened to by taking some from their outer first elements of the iioats next the leading.

curves an angle which differs only two degrees from the angle which these parts made before the alteration. When a turbine is. so modified and used withmy diffuser, its wheel should revolve in about ninety-six hundredths of the time which would be requiredwhen at work without the diffuser and before being vso modified. Y

As some parts of the passages of the water, especially the exits of the wheel, are widened a little by this modification, their liability to being choked is diminished a little. This is of some importance with very small turbines in places where they are liable to'be choked. When my diffuser is used where the wheels are very liable to be choked, it may be well t-o increase the widths of the exits of the wheels twice as much as above mentioned by yother form.

I ldo not conne my claim to the precise forms of my diffuser described above; but I extend it to all forms which are essentially the same in which the parts are so shaped as to form a gradually diverging or spreading passage or passages or in which the passage or passages spread, diverge, or enlarge from the wheel by degrees or by small steps or offsets, so as to cause the stream or streams of water on or after leaving thewheel lto expand, spread, or be diffused gradually or by small steps or degrees, so as to expend a e considerable portion of the momentum which the water has on leaving the wheel in diminishing the pressure of the water or atmos-k phere on the circumference of the wheel or parts of the wheel from which the'water is ejected.

URIAH ATHERTON BOYDEN.

y Witnesses:

BARNABAS WHITNEY, GEORGE STARK.

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