US3313342A

US3313342A - Blowers

Info

Publication number: US3313342A
Application number: US525040A
Authority: US
Inventors: Laing Nikolaus
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-04-19
Filing date: 1966-02-04
Publication date: 1967-04-11
Anticipated expiration: 1984-04-11
Also published as: US3236298A

Description

Apri u, 1967 N. LAING I www2 BLOWERS Filed Feb. 4, 1966 2 SheecS-Shee?l l INVENTOR NIKOLAUS LANG BY /awaa- %ffe/ ATTORNEYS April l1, 1967 N. LAING 3,3%,342

BLOWERS Filed Feb. 4, 1966 2 Sheets-Sheet 2 RES/SNC T0 FLUW INVENTOR NIKOLAUS LANG BY M, M Wwf@ ATTORNEYS United States Patent Office 3,313,342 Patented Apr. 11, 1967 3,313,342 BLOWERS Nikolaus Laing, Hofener Weg 35, Aldingen, near Stuttgart, Germany Filed Feb. 4, 1966, Ser. No. 525,040 Claims priority, application Great Britain, Apr. 19, 1962, 15,401/ 62 8 Claims. (Cl. 16S-124) This invention relates to blowers and this application is a continuation-in-part of my application Ser. No. 274,360, filed April 19, 1963, now Patent No. 3,236,298.

The invention is especially, though not exclusively, concerned with blowers of the cross flow type, that is, blowers comprising a cylindrical bladed rotor mounted for rotation about its axis in a predetermined direction and defining an interior space, and guide means defining with Ithe rotor an entry region and a discharge region, the guide means and rotor co-operating on rotation of the latter in said predetermined direction to induce a ow of air from the entry region through the path of the rotating blades of the rotor to said interior space and thence again through the path of said rotating blades to the discharge region. More especially but, once again, not exclusively, the invention concerns blowers of the cross-how type wherein the guide means and rotor cooperate -to set up a vortex of Rankine character having a core region eccentric of the rotor axis and a field region which guides the air so that flow through the rotor is strongly curved about the vortex core: such blowers will herein be designated tangential blowers and the characteristics of a preferred form of such a machine will be described in detail later.

The normal means for converting velocity to pressure energy is a diffuser, that is a duct which gradually increases in cross-section, going in the direction of flow. Diffusers are well known to have two defects. First, if the duct diverges too rapidly, ow will tend to break away from the walls, forming regions of random eddying which waste energy. Second, if, to counter the first defect the angle of divergence is reduced then energy is wasted in friction along the over-long walls. Normally a diffuser is designed as a compromise to minimise these opposite defects. The angle of divergence is usually small, say 15, so that a conventional diffuser is commonly bulky. A conventional diffuser is also Well known to be subject to appreciable energy loss.

The invention is based on the appreciation that diffuser performance can be improved and/or its size can be reduced lby placing one or more vanes at the narrow end of the diffuser, the vane or vanes dividing flow in the diffuser so that this ow takes place through a number of diffuser portions.

It has been proposed to divide a diffuser by intermediate walls into a plurality of diffusing channels, for example, in British Patent 876,611. One aim of this arrangement has been to enable the walls of each channel to diverge at the maximum angle and thus to enable the divergence of the diffuser as a whole to be increased. However, in practice the intermediate walls introduce friction and energy losses which militate against optimum performance.

An important feature of the present invention is that in contradistinction to the arrangement just mentioned the vanes terminate well short of the downstream end of the diffuser. Preferably the vanes extend over only a fraction of its length, say a quarter or a tenth. Such vanes introduce a minimum of additional friction and enable a substantial increase in the divergence of the diffuser without increasing the energy losses.

If the blower comprises a bladed cylindrical rotor, the diffuser will in general .be rectangular as seen in section take prependicular to flow, with opposite walls parallel to the rotor axis. The vane or vanes in this case will be straight and may be parallel to the rotor axis. If the rotor is of the propeller type, the diffuser will in general be circular in outline as seen in section taken perpendicularly to flow, and the vane or vanes will be annular.

The invention may be utilized with means producing resistance to flow (and hence a pressure drop) either at the suction side or at the pressure side or both, though in some cases having the resistance means on the pressure side will be preferred. As will be appreciated from the foregoing the invention can bring about a reduction in overall size due to a shortening of the diffuser or improvement of its efficiency.

One particularly compact arrangement according to the invention comprises a pair of similar tangential blowers arranged parallel side by side and discharging into a common symmetrically placed diffuser having vanes parallel to the rotor axes at its narrow end and resistance means, for example a heat exchanger, at its wider end. This arrangement has the effect of evening out the peaky velocity profile peculiar to the tangential blower while ensuring flow of substantial velocity adjacent the diverging diffuser walls. The vanes enable a sub stantial increase in the diffuser angle.

Various embodiments of the invention will now be described by way of example with reference to the accompanying somewhat diagrammatic drawings:

FIGURE 1 is a transverse section of a heat exchangerblower combination incorporating a tangential blower with a diffuser having vanes at its upstream end, according to the invention;

FIGURE 2 is a side elevation of the FIGURE 1 unit with a part removed;

FIGURE 3 shows a pair of curves illustrating the functioning of the unit of FIGURES 1 and 2;

FIGURE 4 is a cross sectional view of a second form of tangential blower according to the invention;

FIGURE 5 is a perspective view, with parts cut away, of an axial blower having an annular Vane at lthe upstream end of a diffuser, and

FIGURE 6 is a sectional view showing a modification Y of the diffuser illustrated in FIGURE 5.

Referring to the drawings, the apparatus of FIGURES l and 2 comprises a series of conduits 1 arranged in the form of a rectangular heat exchanger block designated generally 2 and running in parallel spaced relation between a pair of headers 3, 4 at opposite shorter sides of the block. Fluid to be cooled is supplied to one header 3 and flows through the conduits to the header 4.

A blower is provided to blow air through the thickness of the block 2; the blower includes a pair of

similar rotors

5, 6 each having blades 7 arranged in a ring extending parallel to the axis between end discs 8 carrying stub shafts 9 whereby the rotors are mounted for rotation in bearings (not shown) in plane parallel end walls 10 of the unit. One stub shaft 9 of each rotor carries a pulley 11: a belt (not shown) driven by an electric motor or other drive means (not shown) is trained over the pulleys so as to rotate them in opposite directions as shown by the arrows 12. The

rotors

5, 6 have their axes parallel to the longer sides of the block 2 and their length is equal to that of the block.

The longer sides of the block 2 are enclosed by parallel walls 13 which are continuous with similar opposed guide walls 14 extending up to those sides from adjacent the

corresponding rotor

5, 6 and joining the end walls 10. Each guide wall 14 is return-bent adjacent the rotor to provide a smaller vortex-stabilizing portion 14a convergent with the rotor in the direction of rotor rotation and a larger diffuser wall portion 14b. The wall portions 14b diverge at an angle of approximately 90 and form, with the end walls, a wide-angle diffuser 14c having a throat portion at the upstream or narrow end of the diffuser. A symmetrical central guide wall 15 also extending between the end walls 10 provides two

curved portions

16, 17 facing the

rotors

5, 6 diverging steadily therefrom, and meeting at a sharp angle.

In operation of the unit the blades 7 of each rotor 5, 6 (which will be seen to be concave facing in the direction of rotation with their outer edges leading) co-operate with the vortex-stabilizing guide wall portion 14a to set up a cylindrical vortex which is eccentric 'to the rotor axis, the core of this vortex being indicated at V. Air is consequently guided twice through the path of the rod tating blades 7 of each

rotor

5, 6 as indicated by the flow lines MF, F: the vortex causes the flow lines to curve in arcs centred approximately on the core centre, and also causes flow in the line MF, which passes adjacent the core, to be much faster than the flow at the other side of the rotor. For a fuller exposition of the way in which ow takes place reference should be made to British patent specification No. 876,611. Reference should also be made to U.S. Patent No. 3,150,816 as showing flow machines with a pair of contra-rotating rotors; those machines differ in various respects from that here shown, however, and have no diffuser or vane therein.

Air which has passed the

rotors

5, 6 enters symmetrically into the diffuser 14C and passes through the thickness of the block 2. Small vanes 18 supported between the end walls 10 are provided in the narrow or upstream end of the diffuser, to assist the flow.

The vanes 18 divide ow into the diffuser and form diffuser portions 18a through which the divided flow passes.

Now from the foregoing it will be seen that the velocity profile at the section A-A of FIGURE l (that is, as the flows from the two

rotors

5, 6 join just after leaving those rotors) will be shaped somewhat as the curve A in FIG- URE 3. Thus the fastest flow through the diffuser will be adjacent the wall portions 14b. This will tend to reduce break-away losses, but the speed of the air adjacent the wall will nevertheless be reduced by friction while the speed remote therefrom is less reduced. As a result, at the section B-B of FIGURE 1 (that is, just before reaching the block) the velocity profile will approximate to the curve B of FIGURE 3. The speed of the air entering the block 2 will thus be approximately uniform over the whole area of the block, which enables optimum cooling. Due to the diffuser effect the pressure at the section B-B is higher than would be possible in the arrangement hitherto known and described above, so that by reason of the present invention the block can be thicker and/or more closely packed wtih conduits than would formerly have been desirable, thus leading to improved economy of space and material.

The

rotors

5, 6 need not be of great diameter and can with advantage be driven at speeds of the order of 1,500 r.p.m. so as to use electric motors which are relatively small and cheap. Any convenient drive arangement can be used, and instead of driving the rotors from a single motor a pair of similar motors connected to the same supply can be used instead.

It is to be noted that the angle of the diffuser is unusually wide, that such a wide angle can advantageously be employed is at least partly due to the presence of the vanes at the narrow end of the diffuser. This wide angle in turn leads Ito a compact and ecient structure.

FIGURE 4 shows a tangential fan, designated generally 40 and delivering air to a diffuser 41; the fan includes a rotor similar to the rotor of FIGURE 1 and guide means comprising end walls 42 aligned with the ends of the rotor and guide

walls

43 and 44. Guide wall 43 is similar to guide wall 14 of FIGURE l, and guide wall 44 diverges steadily from the rotor going from a line of nearest approach thereto opposite the guide wall 43, The

guide

walls

43 and 44, with the end walls, define the diffuser 41 wherein the

walls

43 and 44 diverge with respect to each other and wherein the narrow portion of the diffuser forms a throat portion. At the narrow end of the diffuser, half way between the

walls

43 and 44 and parallel thereto, is positioned a vane 45. As in the previous ernbodiment, this vane assists ow in the diffuser.

The invention can be applied to centrifugal and axial blowers in addition to tangential blowers. FIGURE 5 illustrates an axial blower S0 supported coaxially within a cylindrical duct 51, which, downstream of the blower is belled out to form a conical diffuser 52 having a throat portion at its narrow upstream end. The annular vane 53 is supported on the spider 54 at the narrow end of the diffuser, to divide flow therein.

FIGURE 6 shows a modification of the FIGURE 5 apparatus, where an axial blower (not shown) blows air into the diffuser 60. At the narrow end of the diffuser is positioned a series of coaxial annular vanes 61 dei signed so that the space 62 between each adjacent pair, and the space between the outer vane and the diffuser wall each act as a diuser portion.

I claim:

1. A blower comprising a bladed rotor, guide means providing an inlet and outlet for said blower and cooperating with said rotor in operation to provide a flow of air through said inlet and outlet, an outwardly flared diffuser having a narrow neck portion adjacent one end joining with the outlet of said blower and having a diffuser outlet at the opposite end thereof, and at least one vane positioned within said diffuser in the neck portion thereof to divide ow therein and to form diverging diffuser portions on either side of the vane and wherein the vane extends only along a minor portion of the length of the diffuser.

2. A blower according to claim 1 wherein the rotor is a bladed cylindrical rotor and the duct is rectangular in cross section taken perpendicularly to flow with the width of said duct substantially equal to the length of the rotor and wherein the vane extends parallel to the rotor axis.

3. A blower according to claim 2 having two rotors and wherein said diffuser is positioned symmetrically with respect to both rotors.

4. A blower according to claim 1 wherein the rotor is of the axial fiow type and said duct is aligned on the rotor axis and is circular in cross section taken perpendicularly to said axis with a radius which increases in the direction of flow through said duct, and said vane is annular and concentric with the rotor axis.

5. A blower comprising a bladed cylindrical rotor mounted for rotation about its axis and having an interior clear of stationary guides, guide means extending the length of the rotor which guide means define a suction region and a pressure region and which cooperate with the rotor on rotation thereof to induce a flow of air from the suction region through the path of the rotating blades to the interior of the rotor and hence again through the path of the rotating blades to the pressure region, a diffuser receiving air discharged from the rotor at said pressure region and having upper and lower walls which as seen from the side of the blower diverge with respect to each other in the direction of ow through the diffuser and wherein the narrow part ofthe diffuser forms a throat portion, means providing a resistance to flow at the downstream end of the diffuser, and at least one vane Within the throat portion of the diffuser situated between said upper and lower walls and extending generally in the direction of flow in said diffuser less than the length of the diffuser, said vane dividing flow in the diffuser to form diffuser portions at either side of the vane.

6. A blower according to claim 5 comprising a plurality of vanes dividing flow in the throat part of the dif,- fuser and forming a plurality of side by side diffuser por tions.

7. A blower according to claim 5 wherein said resistance means comprises a heat exchanger.

8. A blower comprising a bladed cylindrical rotor mounted for rotation about its axis and having an interior clear of stationary guides, guide means comprising end walls substantially aligned with the ends of the rotor and first and second guide walls extending generally parallel to the rotor axis as seen in longitudinal section Which guide means define a suction region and a pressure region and cooperate with the rotor on rotation thereof to set up a vortex of Rankine type having a core region adjacent said first guide wall, said vortex inducing a ow of air from the suction region through the path of the rotating blades to the interior of the rotor and thence again through the path of the rotating blades to the pressure region with said ow of air following lines which are curved about the vortex core region, said guide Walls diverging outwardly from each other in the direction of ow from said rotor to form an outwardly flared diffuser with the narrow part of the diuser forming a neck Iportion and the opposite end forming a diffuser outlet with said neck portion receiv-` ing air discharged from the rotor at said pressure region, means providing a resistance to ow at the Outlet of the diffuser, and at least one vane positioned within the neck portion of the diffuser and extending substantially parallel to said guide walls as seen in longitudinal section and along a minor portion of the length of the diffuser with said vane dividing ilow in the diffuser, and the guide walls as seen in transverse section both diverging from said vane going in the direction of air ow in the diffuser where the angle of divergence of said rst guide wall with respect to said vane is greater 'than the angle of divergence of said second guide wall with respect to said vane.

References Cited by the Examiner UNITED STATES PATENTS 2,032,811 3/1936 Perkins et al 165-122 2,808,237 10/1957 Fosnos 165-122 X 3,035,760 5/1962 Simmons 165-122 X FOREIGN PATENTS 1,252,057 12/1960 France.

606,817 12/1934 Germany.

ROBERT A. OLEARY, Primary Examiner. T. W. STREULE, Assistant Examiner.

Claims

1. A BLOWER COMPRISING A BLADED ROTOR, GUIDE MEANS PROVIDING AN INLET AND OUTLET FOR SAID BLOWER AND COOPERATING WITH SAID ROTOR IN OPERATION TO PROVIDE A FLOW OF AIR THROUGH SAID INLET AND OUTLET, AN OUTWARDLY FLARED DIFFUSER HAVING A NARROW NECK PORTION ADJACENT ONE END JOINING WITH THE OUTLET OF SAID BLOWER AND HAVING A DIFFUSER OUTLET AT THE OPPOSITE END THEREOF, AND AT LEAST ONE VANE POSITIONED WITHIN SAID DIFFUSER IN THE NECK PORTION THEREOF TO DIVIDE FLOW THEREIN AND TO FORM DIVERGING DIFFUSER PORTIONS ON EITHER SIDE OF THE VANE AND WHEREIN THE VANE EXTENDS ONLY ALONG A MINOR PORTION OF THE LENGTH OF THE DIFFUSER.