US1623420A - Propeller - Google Patents

Description

Afiril 5 1927. 1,623,420

w. H. LEmwgBsR rnorsmlsn Fil'ed June 27. 1925 y I -IN\VENTOR.

WILLIAM H. LEINWEZBER K ATTORNEY.

Patented Apr. 5, 1927.

UNITED STATES PATENT OFFICE.

wILLInt n. mntwnnnn, or care aeo, rumors, assrenoa or ONE-THIRD '10 vrc'roa H. Lamar-2a AND ONE-THIRD roctm'rrs n. nnmwnnnn, Born or-ncnrcaeo,

ILLINOIS.

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Application filed June 27, 1925, Serial No. 89,957, and in Canada January 26, 1924.

My invention relates to propellers used for setting in motion fluid whether liquid or gaseous by rotation of the propeller and for moving if 'desired, the structure sup- 5 porting the propeller relatively to the fluid instead of maintaining the said structure stationary and producing motion of the fluid only. In other words my improved propell'er-1s adaptedlfor any purpose for which 9 fans and propellers may be used, whether for producin currents of air or other gases for ventilating and circulating purposes, currents for water circulatin urposes, motion of air craft, or motion oats.

Y My invention is characterized by animroved construction of the surfaces engagmg the fluid, in'such a manner that at any. part of the operating surface of the fan, the ,surface at its edge entering the fluid is in a 0 plane through the entering edge at subst 'tially right angles to the axis'of the propeller' shaft, from which entering edge the operating surface is displaced progressively across the -operatin surface towards the 5 trailing ed of the b ade in the direction of thrust on t e fluid in such a manner that for equal increments across the surface angularly, the displacement increases at a greater rate than proportionally 9 travel across the operating surface, or -in other words the operating surface at any radius of the fan blade is a curve, which preferably imparts uniform acceleration to the fluid. from the entering edge to the trailing 5 edge of the blade, assuming that the propelher is held against axial motion, or theoretically, assuming the fluid to be non-yielding, that would produce uniform acceleration during the same interval of the supporting 0 structure and fan if the latter were movable axially of the propeller. More specifically, the curvature of the blade extending laterally of the propeller is such that each increment of angular travel at any radius across said operating surface, im arts an increment'of velocity to the flui assuming the propeller to be held against axial mo-.

tion, these increments being so related that to the angular each increment of velocity, for equal increments of travel across the operating surface so at sa1d radius of the blade, is equal to each other increment of velocity. In this .man-

ner the'inertia of the mass set in motion axially of the propeller by its rotation,

whether it be the mass of the fluid or'the 65 v mass of the s'upp'ortin structure of the pro- =--peller, is: overcome wit -.maximum efliciency.

The particular curvature given the operating surface of the blade is determined by the maximum displacement axially of the propeller', which is desired at that particular radius of the propeller. blade and is expressed by theformulagiven below. The sharpness of curvature of the operating surface at any radius and for any desired displacement at that radius, is determined by the width of the operating surface of the blade at that radius, this curvature being less sharp for a wide blade than it is for a narrow blade under these conditions A further feature of my invention consists in proportioning the operating surface of the propeller to distribute the thrusts upon .it uniformly over said surface radially of the propeller. This I accomplish by changing the maximum displacement of the op- I eratin surface of the bladeaxially of the -pro e er, so that it progressively decreases as t e radius of the operating surface increases the maximum axial displacements at difl'erent radiibeing inversely proportional to the radii. In this manner I'produce a large displacement near the axis of the propeller where the lineal travel of the operating surface angularly is small and a small displacement of the operating surface at the outer end of. the bladewhere the lineal travel of the operating surface is great, the relation preferably being such that the prodnot of sa1d lineal travel at any radius, by the maximum displacement axially of the operating surface at that radius of the blade,

is equal to the similar product for any'other radius of the blade. In this'manner each radial increment of operating surface produces 96 the same amount of thrust as each other ra-' gpeller consisting of two blades nor to a prodial increment and the thrust produced by the blade is uniformly distributed over its surface radially. A result of the curved distribution of thrust radially but also laterally thereof, or 1n other words conformation laterally of the operating surface of the blade, above described, is thatthe thrust produced-by any ra'dial increment of operating surface '18 uniformly distributed over said increment laterally of the blade. In-this manner I produce not only uniform of the blade I each unit of the operating surface of the blade has exerted upon it the same pressure.

as each other unit of said operating surface- .My invention will best be understood by.

reference to' the accompanying drawings showlng one form in which my mventlon ma be embodled, sa d draw ngs belng as.

fol ows: Fig. 1 shows a propeller. 1n accordance with my invention, 1n side elevatlon,

.Fig. 2 shows the propeller illustrated in Fig. 1,- in front elevation, and.

I Fig. 3.is a sectional view showing a plurahty of sections ai inclusive taken along corresponding lines through one of the blades of the propeller shown in Fig. 2.

@Similar numerals refer 'to similar parts a I throughout the several views. 0.

- -As shown in the drawings, my propeller consists of a hub having a central bore 11 to receive a supporting shaft, from which 1 hub opposite blades 12, .12 extend radially.-

The propeller may be-made of any desiredmaterial for ,example wood or. metal depend i'ng upon the purpose for which it is to be )used and if made of metal it may be made 5in any desired manner adapted for the intended purpose. It will further be understood that I do not limit myself to a pro- ,p ell'er having any particular size or proportion of blades; the number of blades em.

w-p'loyed, and the particular size, shape and proportion of the blades may be determined .;1n any case according to the re uiremcnts of that case and the particular uid to be engaged by the .operatlngsurfaces. of the blades. The essential feature "of my inven tion is that the operating. surface ,-of each blade shallbe shaped to realize the improved operation' "characterizing my invention. To

secure this result each of the blades for' example the upper bladeshown' in; Fig. 2,

is provided with an operating surface hav- 4 ing a curvature of the nature generally described above, forexamplethat illustrated by the several sections of said" blade shown in Fig. 3, said sections being taken at the correspondingly lettered lines in Fig. 2, that. is to say section ais' adjacent the outcr'end of the blade, section b is taken -somewhat nearer the axis of the propeller and soon, section i bemgtaken near the hub 10 of the propeller. In each of the sectionalviews shown in Fig. 3, the right hand edge of the section is the entering edge of the blade into the fluid to be acted upon, said entering edge being designated a 6 2' for the sections, a, b, 13 respectively. The curvature of the operating surface of the blade laterally thereof at each section is determined as follows: the light horizontal lines through the edges (1 b 5 are each in the planeaof rotation of the corresponding entering edge, that is to say in a plane at right angles to the axis of the propeller. lines are through the entering and trailing edges of the blade at the correspondinglse'ction; the distance apart of the entering-and trailing edges for each section is designated In each section, the light vertical by :0 and the axial displacement of the trail- 5 ing edge from the plane'of rotation through-'. the entering edge for any; section is desig-f hated by y.

The curvature of. the operating surface oftheObIade laterally at any radius of the blade, :for example at section i,'is such'that for equalincrements of the abscissam lat ierally, of the operating surface, relatively to thepoint i as a reference point or origin,

the ordinateor :1; [value of the curve shall" PIOgI'GSSIVGly increase by successlvely-greater increments each "than the preceding- 1n amanner to continuously accelerate fluid enigaged by the operating surface, assuming the" propeller to be held against axial displacement. I have. found? that this curve" maybe expressed by the formula of the blade forany particular .widthof operating surface. *In practice I find it advisable and desirable to maintain the fac-- tors f for the different radii of the operat ing surface of any bladeinversely proportional' to said radii, that is to say the-value ofthe factor f at the extreme outer'- end of the operating surfaceshould be halftbe value of the said factor at .a point on the operating surface .half Way from the axis of the'propeller to the outermost radius of tlIepPerating surface and so on for the o crat ng surface at other radii. j, lt will be 0 served that the nature. of the-f jiiurve the same for any value of the factor 7 whether the curve is relatively flat or relatively abrupt being expressed in each case by theexpression In using this formula, to determine the value v of the factor f for the curvature. of the blade amount of thrust it is desired to produce in view of the fluid acted upon and the speed at which the propeller is to be driven. These values give the maximum values of a: and y which are substituted in the formula and the value of f if then equal to 3 divided by The value of the factor f being determined for this particular radius, its'values for other radii are determined by the inversely proportional'relation above referred to.

As a result of the construction described, the operating surface has a curvature .at any particular radius which uniformly accelerates' fluid set in motion by it moving across said 0 crating surface for uniform rotation of t e propeller blade, assuming the propeller to be held against axial motion, and further provides that this uniform acceleration shall be the same across'the operating surface at any radius; The above for- .mula applies to propeller blades whether theyare of uniform width or tapered longi- 1 tudinally, the only difference being thatin the first case the value of a: maximum is constant, whereas in the latter case it decreases in the direction of convergence of the width of the operating surface. From the above it will be observed that the operating surface for my improved propeller is curved bot-h laterally and longitudinally, the former curvature imparting the uniform acceleration referred to and the latter curvature compensating for increasing lineal travel of the operating surface from adjacent the hub of the propeller outwardly radially to the extreme outer end of the operating surface and that in this manner each. unit surface of the operating surface is subjected to the same thrust as each other unit surface thereof.

' To engage the fluid with maximum efli ciency adjacent the hub '10, the-trailing edge I of the operating surface i. is continued towards the axis of the propeller in the form of a smooth curve 13 tangent to the circumference of the hub 10- forming a pocket 14 receiving the fluid adjacent 'the hub and acting upon it substantially as described for the major portion of the operating surface, In this way undesirable eddy currents and losses are prevented adjacent-the hub portion of the propeller.

Each of the blades of any particular propcller is preferably provided with the same kind of an operating surface determined as above set forth and the number of blades in any propeller, and the width of the blades relatively to the spaces between them, are

determined by principles well known in the art. applying to the particular conditions involved In any particular case.

' The formula abovegiven for the lateral curvature of the propeller blades is equallyapplicable for fluid media of different de-.

grees of mobility as follows: Without modi-. ficatlon, the formula and its method of application described applies to fluids theoretically immobile; from data well known in the art concerning any particular fluid, approximately the amount of slip due to mebility-of the fluid maybe ascertained for the particular speed of operation contemplated; the factor of slip being determined and expressed as increased displacement required, the factor f in the formula is multiplied by the slip factor and in this manner the degree of curvature laterally is affected in a manner to compensate throughout its extent for the said slip The resulting factor' fi then becomes the basis for determin- 1 ingthe similar factors at other radii of the operating surfaces of the propeller blades. In a similar manner any other practical condition departing from theoretical operation, maybe compensated for.

' While I have shown m invention in the particular embodiment a o've 'described,'it will be understood that I do not limit myself to this exact construction, but that I may employ, equivalents known to the art. at the time of the filing of this application without departing from the scope ofthe appended claims.

What I claim, is: 1. -A propeller having a ating surfaces, each curved-laterally with axial displacements increasing progressivelymore rapidly than proportional to'the traverse of said surface from its entering edge to its trailing edge, the plane of the entering edge of each of said surfaces being substantially perpendicular 'to the axis of the, propeller, and'each of said surfaces being curved radially of" the propeller making the maximum axial displacements of said surface at different radiisubstantially inversely proportional to said radii.

2.- A propeller having a' plurality of operating surfaces, each curved laterally with axial displacements increasing progressively more rapidly than proportional to the trav-' erse of said surface from its entering edge faces being-curvedradially of the propeller making the maximum axialydisplacements of said surface 'at' different'radii substantially inversely proportionalto said radii.

to its trailing edge, and'e'ach of said; sur' n tially proportlonal to the forum 5 ating surfaces, each curved laterally from its entering edge to its tr g edgi e substan- 'where y is the axial displacement of said surface at any point from the plane of rotation ofits enterin edge and m is the lateral distance of =sai point from said entering ed and having axial dis lacements at its tra g ed substantially inversely proportional to t e distances of said displacements from the pro er axis.

In witness whereof, I hereunto subscribe my name this 24th day of June, A. D. 1925.

WILLIAM LEINWEBER.

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