US2219937A - Propeller blower apparatus - Google Patents

Description

Oct. 29, 1940. A. I. PONOMAREFF 9,937,

PROPELLER BLOWER APPARATUS Filed April 15, 1939 3 Sheets-Sheet l 5 i WITNESSES: mm WK i"; Hmzxnnnm I.Pouonnnsrr. WW QZM L BY Mb.

ATTORNEY Oct. 29, 1940. A. l. PONOMAREFF 2,219,937

PROPELLER BLOWER APPARAJIUS Filed April 15, 1939 3 Sheets-Sheet 2 INVENTOR I RLEXRNDER I. Pmnmn! warm;

ATTORNEY Oct. 29, 1940- A. a. PONOMAREFF 2,

PROPELLER BLOWER APPARATUS Filed A ril 15, 1939 s Sheets-Sheet '5 STRI'IG PRESSURE- INCHES of WHTERn STR'I'IC EFFICIEN Y- PERCENH C R P RC (TY.

WITNESSES: F I a 1 INVENTOR m 9 manual-5:1. Pqunmnsrn 22m. 2/. rs. RMMJ.

ATTORNEY Patented Oct. 29, 1940 UNITED STATES 2,219,937 PROPELLER. BLOWER APPAnA'rUs Alexander I. Ponomareif, Drexel Hill, Pa., assignor to Westinghouse Electric 8; Manufacturing Company, East Pittsburgh, Pa., a. corporation of Pennsylvania Application April 15, 1939 Serial No. 267,978

Claims.

My invention relates to propeller blowers and it has for an object to provide apparatus of this character capable of developing relatively high static pressures.

5 A further object of my invention is to provide apparatus of the above character capable of developing high static pressures while keeping the rotational speed and the noise level at relatively low values.

In the application of propeller blowers for forced draft purposes, the demand for high static pressures has been increasing in an effort to increase the combustion rate, and, therefore, fora combustion and steam generating equipment oo- 5 cupying a given space, to increase the steam production rate. This trend was responsible for the manifestation of the problem of recirculation in an acute way and which, but for the solution by means such as disclosed and claimed in the application of Flanders, Serial No. 163,727, filed September 14, 1937, and assigned to Westinghouse Electric 8: Manufacturing Company, would have been a serious obstacle to further increase in static pressure. As propeller speeds and static pressures tend to increase noise becomes more and more objectionable; and, in my application, Serial No. 176,899, filed November 2'7, 193'], and assigned to Westinghouse Electric & Manufacturing Company, there are disclosed and claimed several features contributing to operation with reduced noise. Among such features are: a projected blade area ratio of 100% or more, the use of six or more blades and a blade length order of 25% or less of the propeller diameter, the provi- I sion of discharge-side airfoil guide vanes having blunt and rounded inlet edges to permit of efficient operation throughout a wide range, of angles .of attack of entering air, spacing of such airfoil guide vanes from the discharge edges of the propeller blades from 9 to 20% of the propeller diameter, the use of a special splitter and guide vane arrangement in the blower discharge elbow section, and operation of the blower below thecritical speed afforded by the various features contributing to high efficiency.

55 general principles disclosed inthe' British patent may be advantageously combined with features referred to in my application aforesaid, the combined arrangement securing, not only increased static pressures and efliciencies, but such increases with reduced propeller speeds and noise. 0 Improved performance in these respects is due to the joint effect of inlet and discharge guide vanes in removing the rotational component imparted to the air by the propeller, the inlet passage for the propeller having guide vanes arranged to im- 10 part a rotational component of motion to the air supplied to the propeller such that the rotational component of air leaving the propeller is reduced through a wide range of blower capacity at a constant speed and the discharge passage having 15 guide vanes curved so as to eliminate the remaining rotational component of motion of air leaving the propeller discharge edges. With this arrangement of inlet and discharge guide vanes it is assured that an otherwise excessive rotational 20 component given by the propeller is efficiently converted without excessive turning by either set of guide vanes. Furthermore, over a range of blower capacities, the presence of the inlet guide vanes assures of reduced variation in the rota- 25 tional component of air leaving the propeller in consequence of which the angle of approach of air entering the discharge guide vanes is narrowed; and, as the discharge guide vanes are preferably of airfoil section having rounded blunt 30 inlet edges permitting of eihcient operation throughout a wide range of angle of attack of the entering air, they are capable of handling air efificiently with a minimum of shock, turbulence or eddying over a considerable capacity range of 5' the blower, the rotational component or twist of the air discharged from the propeller changing with change in capacity for a given speed.

As the propeller has a uniform radial pitch and. as the axial pitch of the blades increases from the leading to the trailing edges, the air would'be discharged therefrom with an increasing rotational component or twist from the blade tips to the hub unless compensatory measures were. taken so that the air may be discharged from the 45 propeller at a more uniform angle from the blade tips to the hub, and, therefore, be susceptible of being handled more efficiently by the discharge guide vanes. To this end, a vortex chamber is provided between the inlet guide vanes and the propeller, the vortex chamber being arranged 'so that, air traversing it from the discharge edges of the inlet guide vanes to the inlet edges of the propeller blades is given a variable twist'or rotational component from the blade tips to the-hub in order to reduce the variation otherwise occurring at the discharge side of the propeller.

The inlet passage is provided with a circumferentially-extending vane, such as disclosed and claimed in the aforesaid Flanders application,

with the result that recirculation, which would otherwise occur and cause disturbance of the flow conditions given to the air in the inlet passage due to the cooperation of the inlet guide vanes and the vortex chamber, is resisted.

Accordingly, therefore, a further object of my invention is to provide a propeller blower having inlet and discharge guide vanes with the discharge guide vanes each having an airfoil section with a relatively blunt inlet edge.

A further object of my invention is to provide a propeller blower having inlet and discharge guide vanes with a vortex or whirl chamber arranged between the inlet guide vanes and the propeller.

A further object of my invention is to provide pre-twist guide vanes with circumferentially-extending vane means cooperating with the propeller blade inlet edges to resist recirculation and consequent pressure pulsations.

,These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a longitudinal sectional view of my improved blower;

Figs. 2, 3 and 4.are detail sectional viewstaken along the lines lI--II, IIIIII and IV-IV of Fig. 1, respectively;

Fig. 5 is a transverse sectional view taken along the line VV of Fig. 1 and viewed in the direction of the arrows;

Fig. 6 is a plan view of the blower outlet as viewed upwardly from the line VI-VI in Fig. 1 and looking in the direction of the arrows;

Fig. 7 is a transverse sectional view taken along the line VII-VII in Fig. 1, looking in the direction of the arrows and with a portion of the outer casing removed and the circumferential vane partially broken away to show the inlet vanes in greater detail;

Figs. 8 and 9 are detail sectional views along the lines VIII-VIII and IX-IX, respectively, of Fig. 1;

Fig. 10 is a sectional view taken along the line X--X of Fig. 1;

Fig. 11 is a developed view of the guide vanes and the propeller blade at the tip of the latter, taken along the line XIXI of Fig. 1;

Fig. 12 is a view similar to Fig. 11 but showing a development at the root of the blade, taken along the line XII-X11 of Fig. l; and,

Fig. 13 is a graph indicating both improved emciency and static pressures due to the provision of the inlet and discharge guide vanes.

In the drawings, there is shown a propeller, at 10, including a hub II and blades l2, and a stator structure, at [3, having a circular wall element I4 defining close clearance with the blade tips and cooperating with the hub to form the blade space, at l5, the latter space, preferably,

charge passage I! for conducting fluid away from the propeller, the adjacent inlet and outlet ends of the passages being close to and aligned with ends of the blade space; and, as the inlet-passage converges toward the propeller and the outlet passage diverges away therefrom, it will be seen that the blower passage has no precipitous change in area and that it provides for efficient conversion of velocity int'o pressure.

The inlet passage, at l6, has a circumferential series of guide vanes I8 arranged therein and functioning to impart a rotational component to the entering air .so that the rotational component of air issuing from the propeller blades I2 is reduced, the residual rotational component of air discharged from the propeller being removed by the circumferential series of discharge vanes I9 arranged in the discharge passage, at ll.

As it'is desirable to provide for eiilcient operation over a wide capacity range, the guide vanes is are of airfoil section and have rounded blunt inlet edges, as shown in Figs. 10, 11 and 12, permitting of eflicient operation throughout a wide range of angle of attack of the entering air with. the result that, even though the angle of the air may vary through a substantial range, due to variation in blower capacity, the discharge guide vanes are nevertheless capable of acting on air to convert efliciently the rotational component of motion into axial motion without shock or eddymg.

To avoid a resonant condition and consequent noise, the relative numbers of inlet guide vanes l8, propeller blades l2, and discharge guide vanes l9 are arranged such that the blades of the propeller and the vanes of either or both of the guide vane groups do not have a common factor. For example, with seven propeller blades, there may be nine inlet guide vanes and. eight discharge guide vanes.

As the propeller blades tend to impart a variable twist or rotational component to the air issuing from the discharge edges from the tips to the hub, the twist or rotational component increasing with reduction in radius, the discharge edges 2| of the inlet guide vanes are not only arranged to give a certain amount of twist or rotation to the entering air but such edges are spaced ahead of the inlet edges of the propeller blades. and converge outwardly relatively to the plane of rotation of the latter to provide a vortex chamber 22, the vortex chamber being approximately trapezoidal in cross section, thereby providing an increasing arc of travel between the inlet guide vane discharge edges and the propeller blade inlet edges, the are being a minimum for the tips ofthe blades and a maximum for the roots of the latter, this being the proper relation for securing an increasing rotational motion with reduction in radius. The vortex chamber 22, therefore, serves to give an increasing rotational component to the air and toward the propeller axis to compensate for the increasing twist or angular component that would otherwise occur at the discharge side of the blades as the hub is approacbed, with the result that air discharged from the propeller has a minimum of variation of angle of discharge from the tips to the roots of the propeller blades so that the air may be better handled by the guide vanes with effective and eificientconversion of the rotational component of motion into axial motion with a corresponding increase in static pressure.

A circumferential vane 23 having its discharge edge 24 arranged transversely of and continuinlet guide vanes. As shown, the vane 23 is preferably carried by the guide vanes l8 and extends rearwardly of the latter so that its discharge edge defines close clearance with-respect to the propeller blade inlet edges.

The prime mover or the turbine, at 25, for driving the propeller, at H), is arranged at the suction side of the latter so as notto interfere with entrance and flow ofair toward the propeller. Accordingly, the stator structure, at l3, embodies an outer casing or housing, at 26, including straight and elbow sections 21 and 28, respectively, and inner core members or elements 29 and 30, whose adjacent ends are aligned with the propeller hub II at the inlet and discharge sides of the latter. The straight section 21 includes a converging portion 3| joined by the throat wall element 32 to the diverging portion 33,the latter cpnnecting with the elbow section 28. .The converging portion 3| is curved in the direction of flow to present an outer convexo-conical surface 34, and the inlet core member 29 is similarly curved to present an inner concavo-conical surface 35, this arrangement of boundary surfaces providing for convergence of the inlet passage, at l6, from the circumferential inlet 36 having a large component of radial direction to its outlet having a large component of axial direction and the construction and arrangement of the inlet passage providingadequate admission area and streamline flow with gradual convergence toward the propeller both in direction and in area. Furthermore, 'the turbine, at 25, may be located quite close to the propeller so that the latter may be supported in an overhung manner by means of the turbine bearings 31 and 38, theend of the turbine spindle 39 adjacent the propeller, as well as the adjacent bearing 38, -being encompassed by, or telescoped with respect to, the inlet core member 29 with the result that the adjacent bearing 38 is arranged relatively close to the propeller,

The prime mover or turbine, at 25, and the propeller, at 10, are supported directly and independently of the blower stator structure, at l3, with the result thatthe latter is relieved of load and working stresses dueto the prime mover andthe propeller. To this end, the turbine is shown as provided with a supporting foot construction 40 carried by the bedplate M, and the blower stator structure, at l3, may be supported in any suitablemanner so long as the outer casing 26 has thethroat portion thereof concentric with the propeller. As shown, the stator structure is carried and held-in aligned relation with the propeller by supports 42 and 33, the support 62 being mounted on the bedplate til and the support 43 being constituted, for example-by a bulkhead. The inlet guide vane outer and inner edges are preferably attached to the converging portion, 3! of the outer casing and to the inlet core member 29, respectively. Likewisethe outer and inner edges of the discharge guide vanes are connected to the diverging portion 33 of the straight section and to the core member 30,.respectively.

As disclosed and claimed in my application aforesaid, the elbow section 28 is divided into a multiplicity of flow passages 41, 48, 49 and 5B of increasing radii of curvature by means of splitter vanes BI, 52 and 53. The discharge-side core member 30 has a conical extension 54 intersecting the passages 49 and 50 and attached at its outer end 55 to the outeror convex wall of the elbow section. As the core member 54 intersects the passages 43 and 50, to avoid turbulence, it has cooperating therewith airfoil vanes 58 and 51 arranged normally withrespect to the splitter vanes, the vane 56 having its opposed edges attached to the splitter vanes 52 and 53 and the vane 51 having its edges attached to the vane 53 and to the outer wall 28 of the elbow.

While the discharge end 58 of the elbow section may have any desired section or shape, as shown in Fig. 6, it is preferably made rectangular to simplify the connection. thereof to the boiler housing to be supplied with air. Furthermore, with this shape of outlet, the width may be varied to provide the desired divergence, with the result that the entire passage of the blower has no precipitous change in area, the inlet passage, at It, gradually converging and the discharge passage, at 11, together with the elbow section, gradually diverging so that velocity imparted to the air by the propeller may be efllciently converted into pressure. Aside from the flow passage serving eifectively in this manner, as already pointed out, the inlet guide van'es N3, the vortex chamber 22, the circumferentially-extending vane 23, and the airfoil section discharge vanes l9 cooperate effectively to remove therotational component due to the propeller, the pre-twist effect imparted by the inlet vanes l8 and by the vortex chamber 22 assuring that the rotational component of air leaving the propeller is both reduced'and the angle thereof made substantially uniform from the hub to the blade tips, and, with substantial uniformity in the angle of discharge from the propeller, the guide vanes [9 are better able to .convert the rotational component of motion of air into axial motion thereof, the discharge guide vanes l9 being of airfoil section and having rounded blunt inlet edges to permit efficient operation throughout a wide range of the angleof attack so as to convert rotary into axial motion over a wide range of variation of angle of approach of the air, such variation occurring because of change in capacity of the blower at a given speed.

Fig. 13, based on actual tests, shows the improvement both with respect to static efficiency and static pressure effected by the use of inlet and discharge guide vanes as compared to the use of guide vanes only at the discharge side or a guide vane only on the suctionside. Referring to static eiliciency, curve (a) for guide vanes both at the inlet and at the discharge sides represents a substantial improvement over curve (b) for guide vanes at the discharge side only and still more over curve (0) for guide vanes at the inlet side only. V

The curves for static pressure show a similar relation, the curve ((5), for guide vanes at both the, inlet and the discharge sides showing a higher static pressure than either curves (e). or 0), curve (e) being for guide vanes on the discharge side only and curve if) for guide vanes at the inlet side only.

These curves not only show that staticefficiency is substantially improved when guide vanes areemployed both at the inlet and discharge sides, but that, at the maximum static efliciency, which-is normally the operating condition of' the blower, the static pressure-developed by the blower equipped with the combination of inlet'an'd, discharge side guide vanes is about 25% higher than that obtained on the blower with discharge guide vanes only.

operating speed for the same static pressure requirements, the reduction of speed being important due to' high stresses encountered in propeller blades and the hub and also because it results in reduction in noise generated by the blower. Aside from the blower noise being reduced because of reduction inv the operating speed, it is also reduced because the air enters the discharge guide vanes at smaller angles due to the effect of the inlet guide vanes and the vortex chamber on the air entering the propeller.

A comparison of curves (a) and (b) of Fig. 13 shows that curve (a) for suction and discharge guide vanes is relatively flatter than curve (b) for discharge guide vanes only, that is, a high efliciency is obtained through a wide range of blower capacities with both sets of guide vanes.

From the foregoing, it will be apparent that improved performance in the respects indicated is secured due to cooperation of the various features. Referring to Figs. 11 and 12, the inlet guide vanes are so curved as to impart to the entering stream of air a rotational component opposed tothat given by the propeller with the result that the propeller rotational component may be reduced under all operation conditions, or completely neutralized at one condition; however, as blowers customarily have anoperating range, and not a single operating condition, discharge guide vanes are employed to effect conversion of the residual rotational component into static pressure. The presence of inlet guide vanes imparting a rotational component to the entering air in opposition to that of the propeller improves the cooperative relation of the propeller and the discharge guide vanes in that, over a range of blower capacities, the inlet guide vanes reduce the variation in the rotational component of air leavingthe propeller and in consequence of which the angle. of approach of air entering the discharge guide vanes is narrowed, thereby aiding in the action of the latter in dealing with the residual rotational component. As the discharge guide vanes are preferably of airfoil section with round blunt inlet edges, permitting of emcient operation throughout a wide range of angle of attack of the entering air, this feature, taken with the inlet guide vanes, tending to reduce the angle, assures of eflicient operation over a wide range. While the airfoil guide vanes are capable of handling air discharged from the propeller with a rotational .component which increases from the blade tips to the hub, thereby resulting in variation in the angle of attack of entering air from the inner to the outer ends of the discharge guide vane inlet edges, it is desirable to compensate sojfar as possible for this variation in order to further improve the performance or range of eflicient- This results in a considerable reduction of the blower sary to reduce pulsations, particularly where the static pressure at maximum operating speed is in excess of 15 inches of water, its effect in reducing recirculation, eddying, and shock loss in the inlet passage is conducive to improved performance of the vortex chamber.

The foregoing features contribute to the improved performance indicated in Fig. 13, from' which it will be noted that the efiiciency is improved and that the propeller speed'is reduced as compared to arrangements having vanes at the inlet side only and at the discharge side only. The reduction in speed is particularly important as it gives a wide margin below the critical speed when operating at high static pressures, and, as already pointed out, reduction in speed also reduces the noise level.

, While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire,

therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In a blower, a propeller having a hub with blades carried thereby; a stator structure including a wall having close clearance with respect to the blade tips and cooperating with the hub to provide an annular space for the blades; said stator structure having annular inlet and discharge passages whose adjacent ends are aligned with and close to ends of said blade space; said inlet passage converging toward the propeller and said discharge passage diverging therefrom; and a circumferential series of guide vanes in the inlet passage and curved so as to impart a rotational component of motion to the air stream in adirectlon opposite to that imparted thereto by the propeller to reduce the rotationalcomponent.

of motion of air discharged by the propeller; said inlet guide vanes having their discharge edges spaced from the propeller blade inlet edges and converging outwardly radially with respect to the latter and the portion of the inlet passage between the guide vanes and the propeller curving inwardly and toward the propeller to provide a vortex chamber for imparting to the air stream a rotational component of motion which increases from the propeller blade tips to the hub.

2. In fluid translating apparatus a propeller having a hub with blades carried thereby, a stator structure including a wall having close clearance with respect to the blade tips and cooperating 5 with the hub to provide an annular space for the blades; said stator structure having annular inlet and discharge passages whose adjacent ends are aligned with and close to ends of said blade space; said inlet passage converging toward the propeller and said discharge passage diverging therefrom; a circumferential series of guide vanes in theinlet passage for imparting a rotational component of motion to the fluid stream in a direction opposite to that imparted thereto by the propeller to reduce the rotational component of motion of fluid discharged by the propeller; and circumferential vane means in the inlet passage carried by the inlet guide vanes, extending I in the direction of flow, and having its discharge edge arranged transversely of and contiguously to the inlet edges of the propeller blades to resist recirculation of fluid.

3. In fluid translating apparatus, a propeller having a hub with blades carried thereby ;'a stator structure including a wall having close clearance with respect to the bladetips and cooperating with the hub to provide an annular space for the blades: said stator structure having annular inlet and discharge passages whose adjacent-ends are aligned with and close to ends of said blade space: said inlet passage having a circumferential inlet spaced axially from its outlet adjacent to the blade space and. from its inlet having a large component of radial direction, curving inwardly to its outlet havinga large component of axial direction; a circumferential series of guide vanes in the inlet passage and curved so as to impart a rotational component of motion tothe fluid stream in a direction opposite to that imparted thereto by the propeller to reduce the rotational component of motion of fluid discharged by the propeller: said inlet guide vanes having their discharge cdges converging radially outward with respect to the plane of rotation of the propeller and spaced from the propeller blade inlet edges to provide an intermediate portion of the inlet passage serving as a vortex chamber for imparting to the fluid stream supplied to the pro peller a rotational component of motion which increases from the blade tips to the hub; and circumferential vane means in the inlet passage, carried by the inlet guide vanes, traversing the vortex chamber in the direction of flow. and having its discharge edge arranged transversely of and contiguously to the inlet edges of the propeller blades to resist recirculation.

4. In fluid translating apparatus, a propeller having a hub with blades carried thereby; a stator structure including an outer casing and inlet and discharge core members co-axial therewith and having their adjacent ends aligned with opposite ends of the hub; said casing comprising inlet and discharge portions at the inlet and discharge sides of the propeller and an intermediate portion having close clearance with respect to the blade tips and cooperating with the hub to provide an annular blade space; said inlet portion and said inlet core member having opposed convexo-conical and concavo-conical surfaces providing, for the blade space, a converging inlet passage having a circumferential inlet with a substantial component of radial direction and curving inwardly and toward its outlet having a substantial component of axial direction; said discharge portion and the discharge core member providing a diverging discharge passage for the blade space; a prime mover including a stator having spaced bearings and a rotor having a shaft journaled in the bearings; said shaft and bearings being in axial alignment with said casing; the

portion of the prime mover stator provided with the bearing adjacent to the propeller being telescoped with respect to the inlet core member and the rotor shafthaving a portion overhanging the latter bearing with its terminal part extending beyond the inlet core member and in the space between adjacent ends of the. core members;'

meansfor' connecting the propeller hub to said terminal part; and a circumferential series of guide vanes in the discharge passage and having their ends connected to said discharge portion and to said discharge core member.

5. In fluid translating apparatus, the propeller having a hub with blades carried thereby; a stator structure including an outer casing and inlet and discharge core members coaxial therewith and having their adjacent ends aligned with opposite ends of the hub: said casing comprising inlet and discharge portions at the inlet and discharge sides of the propeller and an intermediate portion having close clearance with respect to the blade tips and cooperating with the hub to provide an annular blade space: said inlet portion and said inlet core member having opposed convexo-conical and concavo-conical surfaces providing, for the blade space, a converging inlet passage having a circumferential inlet with a substantial component oi radial direction and curving inwardly and toward-its outlet having a substantial component of axial direction; said discharge portion and the discharge core member providing a diverging discharge passage for the blade space; a prime mover including a stator having spaced bearings and a rotor having a shaft journaled in the bearings; said shaft and bearings being in axial alignment with said cas ing; the portion of the prime mover stator provided with the bearing adjacent to the propeller being telescoped with respect to the inlet core member and the rotor shaft having a portion overhanging the latter bearing with its terminal part extending beyond the inlet core member and in the space between adjacent ends of the core members; means for connecting the propeller hub to said terminal part; a circumferential series of guide vanes in the inlet passage and joining the inlet core member to the outer casing; a circumferential series of guide vanes in the discharge passage and joining the dischargecore member to the outer casing; means for supporting the stator structure and maintaining it axially aligned with the propeller; and means independent of the last-namedmeans for supporting the prime mover.

ALEXANDER. I. PONOMAREF'F.

CERTIFICATE OF CORRECTION.

' Patent No. 2,219,957, October 29, 191w.

V ALEXANDER I. PONOMAREFF.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 75, for the syllable "continu" read --contigu--; and that the sold Letters Patent should be read with this correction therein thaIt the same may conform to the record of the cese in the Patent Office.

Signed and sealed this 10th day of December, A. D. 191w.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

Images