DE23070C - Innovation in centrifugal pumps - Google Patents

Description

IMPERIAL

PATENT OFFICE

CLASS 59: Pumps.

The present invention relates to a new blade shape for centrifugal pumps.

The centrifugal pumps constructed hitherto suffer from two drawbacks: on the one hand, they have them too high a number of revolutions, on the other hand they create a lot of friction and mass losses.

As for the first problem, it can be easily dealt with with any small pump prove by the number of revolutions is often 2000 to 3000 per minute. but Larger pumps would also work with the usual ratio of the outer wheel diameter to the Pipe diameter require too high a number of revolutions as soon as the delivery head becomes unusually high.

As for the latter problem, it will be easily understood if one considers how sharp curves and deflections the water must often traverse, and how strong shocks it is exposed to. For all rationally constructed pumps with a guide housing, i.e. with a cover which encloses the impeller on the outer circumference for the purpose of collecting the escaping water and delivering it to the pressure pipe, it must be emphasized that the water never: tangentially out of the impeller into the Leader housing emerges, but in a direction that deviates significantly from the tangent to the wheel. This results in significant material losses, because the water cannot remain in the direction given by the paddle wheel, since the guide housing forms a solid wall against which the water impacts, with only the side component of the original speed along the guide housing towards the pressure pipe reach. The angle at which the water verläfst the impeller is, in the ordinary pump 10-3 o ° and more, while it is made much smaller in the present pump, on average 2 to 3 ^0, not more than 5 °; so that. the water comes out of the wheel very close to tangential. Furthermore, the usual pumps always have a transition neck on the guide housing, because the speed at which the water exits the paddle wheel is much greater (two to five times) than that in the pressure pipe. · "; This transition neck is much too short to prevent losses of effect due to changes in speed. Pumps without a guide casing usually have the disadvantage that this is the case. the water emerges with too great velocity from the wheel; so that losses Effect ¹ are formed. These many water deflections and power losses due to contraction due to rapid changes in cross-section and speed have a detrimental effect on the degree of efficiency, so that at the same time, in view of the high number of revolutions, the permissible delivery head for the centrifugal pumps is only very low.

The present pumps, on the other hand, should be arranged with the aid of the blade shape in such a way that first, the number of revolutions remains small by choosing a suitably large diameter, and Secondly, the water is conducted in an expedient manner and all unnecessary cross-sections and Changes in speed and all violent material losses are avoided. Middle of this new principle, the admissible funding

Height for centrifugal pumps increased from 5 to 10 m to 100 to 200 rh and more.

The new blade shape forms a variable Archimedean spiral, namely one in which the polar equation r = a · φ of the Factor either a decrease or gleichmäfsig ungleichmäfsig when the polar angle φ increases, where r is the radius vector. The law for the decrease or increase of the factors depends on the given circumstances.

The number of blades depends on the size of the blades and their ease of manufacture certainly. You can either uninterrupted all of the entry scope of the wheel extend to the extent of the exit, or they can be partially shortened, so that either on There are more shovels at the inlet than at the outlet, or vice versa.

The procedure for tracing the blade shape is as follows:

First of all there is always a diagram for the speeds and an auxiliary construction required, after which the blade can be recorded. Let them be the following Sizes given (see Fig. 1), provided that the liquid on the inner circumference enter the paddle wheel:

r _{t is} the inner wheel radius,

r · ,, the outer wheel radius,
' g _t the absolute speed of the water when entering the paddle wheel,

g _{2 the} same exit speed,

V _{1 is} the inner peripheral speed of the wheel,

Vi is the external peripheral speed of the same,

e _{f is} the radial components of g _t (this speed can now be changed a bit to allow for a reverse motion, similar to that of a ship's propeller),

e _{t is} the radial component of g ₂ ,

U _{1 is} the radial speed with which the water moves along the blade when entering the wheel,

« ₂ this relative speed at the exit,

b _{t is} the blade height at the inlet circumference,

b _{2 the} same for the exit circumference.

In order to first record the diagram of the speeds, plot the circumferential speeds of the wheel V ₁ = AB and e »j '= AG in an arbitrary scale on the straight line AG in Fig. 2, divide the distance BG into several equal parts, establish CD E in sub-points B. . . . Lothe up and down, set in Loth in B the radial entry speed C ₁ = BB ' and draw B'-G' parallel to AG. This line B'-G ' cuts the lot in C £>' £ '.... You connect these points CD' £ '. . . with A through straight rays which intersect the solder BB ' at the points marked in the figure, and from these points draws parallels to AG according to the corresponding perpendiculars, that is to say to- C "D" E " ... below the line ..AG take the associated blade heights BB ₁ = b ,, DD ₁ ... .GG ₁ = b ₂ in the plumb bobbins, connect the points B ₁ C ₁ D ₁ through B ₁ a parallel to AG, which intersects the Lothe in C ₁₁ D _u E ₁₁ .... G ₁₁ , strike around the points C ₁ -D ₁ E ₁ ... .. as centers circular arcs with CC ₁₁ DD _n EE ₁₁ .... as a radius downwards, connect the intersection points of these circles in AG with C ₁ D ₁ E ₁ .... With straight lines, draw parallels to this through C _n D ₁₁ E ₁₁ .. ·.> To AG and look up their points of intersection around the points CDE .... as center points; 'look up the upper perpendiculars. In the sections CC "DD'" E '" .... one now has a measure" for "the relevant radial ones Components of the absolute velocities of water. To prove this, one has to note the following:; Λ

In a given time (e.g. every second) the amount of water to be pumped is unchanged the same when entering the wheel, when flowing through it and when exiting. When entering, this amount of water per second is = 2 r _t π b, · e _t , which product remains constant for each radius. For an arbitrary radius r _x , Fig. 1, which may correspond to the point D in Fig. 2, the blade height b _x = DD ₁ and the peripheral speed of the wheel V _x = AD, while the unknown radial speed component with the aid of the following equation Is found:

R 2, η b, * e, ₌ r '
2 r _x -π 'b _x r _x

b _x

Now it is in the diagram DD " how easily

v
watch = · e and therefore

DD '

DD "=

b _x

the radial water velocity for r _x
was to be proven.

For exact calculations, instead of the actual blade heights, something smaller must be used Insert diagram, whereby the blade thicknesses are taken into account in the scope.

Plotting the sake of clarity to another position, Fig. 3, the lines A-G with the Lothen BB 'CC "DD"' EE '. "... from the first graph on, pulls by B' a parallel B'- A ' to AG, then in B we now assume a direction BH for the absolute entry velocity g, (it can either be to the right of BB' or in the same, or to the left

from this line), connects H with A, then one has the inner circumferential speed V ₁ in AB , the absolute entry speed g _t in BH and the blade speed u _{] t} in AH, ie the speed at which the water etc. moves along the Shovel moved (see Fig. I). Let us further assume a line GJ in G so that _ / lies in a parallel through G '" with AG , further that GJ is equal to the absolute exit velocity g ^ , or that the exit angle A_JG A receives the desired size, namely for the Pumps with a guide housing; up to 2 ° or 3 ⁰ or 5 ⁰ , while for those without a guide housing the angle can be made larger (50 to 90 °). Then, in a manner similar to that previously in AG: 'the outer circumferential speed # ₂ , in GJ the absolute exit _{speed ^ 2} ^and in AJ the blade _{speed W 2. The} directions of all these speeds can be seen in the diagram.

The rays AH and AJ are now extended to H ' and J' either by a straight line or, according to fixed points of view, by any arbitrarily curved line with one another.

For the sake of simplicity and as an introduction, a straight line is assumed in the figure, while curved lines will be discussed below.

The points of intersection of the straight lines H '- /' are connected to those that are extended upwards

Lothen BB 'CC "DD'" with A through

straight rays, runs through C "D '" E "'

Parallels with AG after these rays and finally lays a curve Hc d efj through the found points. Then all speeds are determined by the figure. Because for an arbitrary radius r _x , which may correspond to the point D , one has the absolute speed g _{x of} the water in the straight line Dd drawn in thought, the circumferential speed V _x in AD and the blade speed U _x in Ad .

If you transfer the peripheral speeds from this diagram to a coordinate system (or radius) as abscissa, and the absolute velocities as well as the blade velocities as the ordinates above, two curves are obtained which show the increase and decrease of these two speeds specify exactly.

But if one wants to prescribe a different law for their growth and decrease for these speeds, one must either transform the connecting line H'-J ' into a single or multiple curved line or change the blade heights BB ₁ CC, DD ₁ .... while GG _{1 of} course remains unchanged.

This is the graph of the speeds.

To carry out the auxiliary construction, in Fig. 4, on the straight line AG, take the angles / S_ HA G and / $ _ JA G from the previous Fig. 3, make AB == r _t and AG = r ₂ , erect in B and G Lothe BH and GJ, which intersect the legs AH and AJ of the plotted angles in H and J , and lay such a line through these points that the present area AGJH is geometrically similar to the area AGJ 'H' in the previous Fig. 3 will. Then 4 has the area in Fig. Peculiarity, that the Loth BH a-value A _T of the factors α in the polar equation r = α φ of the blade shape for the radius vector r _t, and Loth GJ another value # ₂ of the same factors for the radius vector r ₂ , hence the intermediate Lothe in CDE .... represent different values of α for the intermediate radii vector.

Now, in Fig. 5 , plot any length on the straight line MN , divide this into any number of equal parts, set up Lothe in the partial points (not indicated in the figure for the sake of clarity), and in the previous Fig. 4 (there also not given for the sake of clarity) the length BG in as many equal parts and erect in the same Lothe up to the line HJ. Then one has the property of the Archimedean spiral according to these plumb lines or in other words for the various values a _t .... O _{3 of} the factor α as a radius the corresponding circumferences 2 a _t π ... . 2 _«2 to determine π, the same to dividiren by a number η (ζ., 8), and then ablate the ratios found in the Lothen FIG. 5 upward and endlich.die upper points by a suitable line M'-N ' to connect. If one extends the plumb bob in N so far upwards that the length NO equals the outer radius of the wheel in any measure; - ₂ and OP equals the inner radius r , connects P with M ' by a straight line, draws a straight line through M A parallel to NE, which intersects the curve M 'N' in α , falls from α a Loth to MN to «,, runs through α, a parallel to M'-P to N-Obisl> ₂ , which M'-N ' cuts in b , a plumb bob falls from b to 6, and continues in this way until one comes over the line N-O , the figure is finished. (If you think it is more correct, you can put the line PM ' through P and M instead of M' and proceed as before.)

The reason for this procedure can easily be seen if one considers that the angles which include the blade speed with the peripheral speeds in the diagram or, what is the same, the angles which the vane walls make for a given radius with the tangents enclose their circles, are determined by the diagram and therefore the blade shape must be like this,

that this condition is indeed fulfilled. If one looks at the shape of the blade, which is to be discussed immediately, one soon finds that for ^r / ₈ rotation Y ₈ of 2 a _x π ■ more must be set to the previous one in order to obtain the radius vector.

One has z. B. at the beginning the radius vector r _; and after '/ ₈ revolution ' / _{s of} the circumference of the value α in the polar equation add r = α φ as a radius, that is, MM ' = Pa ₂ , so that the radius vector == r _t - \ - Pa ₁ = Oa ₃ will etc

This is the auxiliary construction.

Now you can mark the shape of the shovel yourself.

In Fig. 6 one _{draws two} circles with r, and r, divides the circumference of the same into η (here 8) equal parts, connects the subpoints in circumference with the center Q by straight lines, inserts the circle in O of the auxiliary construction Oe ₁ , takes this length in the new figure from Q to Q , to β, takes O b ₂ into the circle, takes it from Q ₂ to γ and continues like this until one arrives at the outer circumference of the circle. Through the found points α β y ^ .... the desired blade shape can finally be placed.

The above method läfst very abbreviated as follows:. In the diagram One set of velocities in Figure 3 on the line AG (in the figure, not shown) from A to G at the radius r ₂ from wherein A is the start point, be constructed in the End points one plumb line upwards, lengthen all rays AHAc etc. to this plumb bob, determine for the greatest length (x) in the plumb bob, i.e. up to the point of intersection with the extended ray AH as a radius the length of a corresponding circle circumference, divide it by η ( 8 here) and place now to the line AG Loth y so, that the through the beam in the AH perpendiculars

cut length is given the size - 2 χ π . On a line (similar to NO in Fig. S) place the radii r ₁ and r _t , divide the distance between r _f and r 2 into as much equal parts as in BG in Fig. 3, erect Lothe and in the plumb line _{belonging to ^ 2} insert the length y with all intersection points of the rays from Fig. 3, connect this with the starting point of the straight line (O in Fig. 5 correspondingly) and lay a curved line through the points of intersection of these rays with the plumb bobs Line (similar to M'-JV ' in Fig. 5), put an angled triangle of 45 ° at the end point of r, draw a line up to the curved line, fall a plumb line, draw a line again at the angle of 45 ° ° and drop a plumb bob, 'until one has come to the end point of r ₂ . The intersection points found in the straight line are exactly the same as a _t ^ 2 ^ ₂ · · · · in Fig. 5.

The practical design of these pumps is illustrated in FIGS. 7 to 14, namely FIGS. 7 and 8, 9 and 10, 11 and 12, 13 and 14 each show a pump, while the blade shape required for different cases is itself made up of the 8, 10, 12 and 14 can be seen. For low head, the inventor generally uses divergent side surfaces instead of the convergent side surfaces of ordinary pumps. This is because in FIGS. 7 and 9 the blade height increases from α β at the inner circumference to γ d at the outer circumference, while this blade height usually decreases from the inside outwards.

But this divergence of the side surfaces can decrease, the higher the delivery head becomes, so that the wheel has parallel, Fig. π and 13, or convergence side surfaces. This happens, in order to avoid that the blade walls move too close to one another on the outer circumference will.

The water wouldn't be tangential. leak enough because of the speed of the water would be assumed to be the same as that in the pressure pipe when exiting the wheel, then take it the exit velocity of the water is greater than the velocity of the water in the Pressure pipe, "but one must have a gradual transition between these speeds determine.

The inventor does this by using a diffuser (called "transition neck" in common pumps) of greater length, but for ease of manufacture it bends it and wraps it around the actual housing of the pump in one or more turns. In Fig. 10 such a diffuser is shown, where it extends from i, going through fg and h , to the pressure pipe at i , while the actual housing is indicated by α b cd and e .

In Fig. 14, a diffuser is also indicated by efghi , while ab ede denote the actual guide housing.

This diffuser, at generally higher delivery heights, enables the water as well with parallel and even convergent side surfaces emerges almost tangentially from the wheel and thus fulfills the stated condition.

Claims (1)

Patent claim: The arrangement of the blade, in the form of a variable Archimedean spiral according to the information contained in the description is constructed. For this purpose 2 sheets of drawings. BERLIN. PRINTED IN THE REICH PRINTING COMPANY.