EP0458880A1 - Ventilateur centrifuge dote de pales a profile d'aile dans une enveloppe annulaire en volute - Google Patents

Ventilateur centrifuge dote de pales a profile d'aile dans une enveloppe annulaire en volute

Info

Publication number
EP0458880A1
EP0458880A1 EP90903670A EP90903670A EP0458880A1 EP 0458880 A1 EP0458880 A1 EP 0458880A1 EP 90903670 A EP90903670 A EP 90903670A EP 90903670 A EP90903670 A EP 90903670A EP 0458880 A1 EP0458880 A1 EP 0458880A1
Authority
EP
European Patent Office
Prior art keywords
blower
envelope
flow
annular
blades
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90903670A
Other languages
German (de)
English (en)
Other versions
EP0458880A4 (en
Inventor
Martin G. Yapp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Airflow Research and Manufacturing Corp
Original Assignee
Airflow Research and Manufacturing Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Airflow Research and Manufacturing Corp filed Critical Airflow Research and Manufacturing Corp
Publication of EP0458880A1 publication Critical patent/EP0458880A1/fr
Publication of EP0458880A4 publication Critical patent/EP0458880A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44—Fluid-guiding means, e.g. diffusers
    • F04D29/441—Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
    • F04D29/444—Bladed diffusers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D17/08—Centrifugal pumps
    • F04D17/16—Centrifugal pumps for displacing without appreciable compression
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
    • F04D29/281—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for fans or blowers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
    • F04D29/30—Vanes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
    • F04D29/5826—Cooling at least part of the working fluid in a heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2250/00—Geometry
    • F05D2250/50—Inlet or outlet
    • F05D2250/52—Outlet

Definitions

  • This invention relates to centrifugal blowers and fans.
  • Centrifugal blowers and fans generally include an impeller that rotates in a predetermined direction in a housing, and may be driven by an electric motor.
  • the impeller has curved blades which draw air in axially, along the impeller's axis of rotation, and discharge air radially outwardly.
  • blowers are used in a variety of applications, which dictate a variety of design points for pressure difference, airflow volume., motor power, motor speed, space constraints, inlet and outlet configuration, noise, and manufacturing tolerances.
  • blade exit angle the angle of the blade tip relative to a tangent to the tip. This angle is called the "blade exit angle”. If the blade exit angle is greater than 90°, the impeller is said to have forwardiy curved blades; if the blade exit angle is less than 90°, the impeller is said to have rearwardly curved blades.
  • GB 2,080,879 discloses a rearwardly curved centrifugal blower with stator vanes to convert radial Q flow to axial flow.
  • GB 2,166,494 discloses a centrifugal impeller in a rotationally symmetrical cone-shaped housing, with guide vanes to produce an axial discharge.
  • GB 1,483,455 and GB 1,473,919 disclose centrifugal blowers with a volute.
  • GB 1,426,503 discloses a centrifugal blower with dual openings.
  • the invention features a rearwardly curved centrifugal blower having an annular envelope around the impeller, so that the rotating impeller draws air in through a central inlet and forces it radially outward into the envelope and out of an annular discharge.
  • Multiple airfoil vanes are positioned in the annular envelope, in two axially displaced stages. The vanes are angled to turn and diffuse airflow entering the envelope.
  • the blower comprises means for attaching a flow resistance element (e.g. a heat exchanger) at the annular discharge.
  • a flow resistance element e.g. a heat exchanger
  • the annular envelope is thin (e.g. its inner diameter is at least 80% of its outer diameter).
  • the blower has a blade design and rotational velocity design range which generates flow entering the annular envelope at an angle between 60° and 70° with respect to the blower (impeller) axis.
  • the airfoil vanes turn the flow in the envelope to produce a flow at the discharge at an angle between 0° and 10° with respect to the blower axis.
  • the vanes are sized and positioned to diffuse flow in the envelope to produce a discharge flow rate of between ⁇ 10 and 40 feet/sec.
  • the airfoil vanes of the invention significantly enhance efficiency by converting tangential velocity into static pressure.
  • the tangential velocity energy is essentially fully extracted in the form of pressure, so that the aiflow leaving the discharge has essentially no residual tangential velocity.
  • the resulting design is also relatively quiet.
  • the heat exchanger e.g. an automobile air conditioning evaporator downstream of the discharge provides significant flow resistance; airflow through the heat exchanger is substantially more efficient as a result of the uniform axial flow at the discharge.
  • the invention also enables a relatively compact package.
  • Fig. 1 is a cross-section of a centrifugal blower and automobile air conditioner evaporator.
  • Fig. 2A is a cross-sectional representation of the impeller blades of the blower of Fig. l.
  • Fig. 2B is an enlarged detail of a portion of Fig. 2A.
  • Fig. 3 is a top view, partially broken away, of the annular envelope of the blower of Fig. 1.
  • Fig. 4 is a graph of pressure as a function of tangential swirl velocity.
  • blower 10 includes an impeller 12 consisting of a plurality of blades (14 and 15, shown in Fig. 2) which are described in greater detail below. Impeller 12 is driven by an electric motor 16 attached to impeller axle 18. Impeller 12 rotates within stator 20, which is a part of generally cylindrical housing 21 extending co-axially with impeller 12 and motor 16. Generally cylindrical motor housing 22 forms the inner diameter of annular envelope 24. The outer diameter of annular envelope 24 is established by housing 21. Airfoil Vanes
  • Fig. 3 is the centerline (axis) of the motor, blower and impeller.
  • the vanes extract tangential (rotational or swirl) velocity from air leaving the impeller, and they recapture that energy as static pressure.
  • Evaporator 30 is attached to the outlet 28 of envelope 24. Swirl in the airflow reaching evaporator 30 is substantially eliminated and air pressure across the evaporator is increased. Specifically, the vanes 25 and 27 are important in part because about 1/4 to V2 of the flow energy produced by a rearwardly curved centrifugal blower is in the form of velocity; the airfoil vanes recapture a substantial (40-80%) percentage of this flow energy.
  • V airflow veloc ty leaving the impeller
  • V.. is the impeller tip velocity
  • Vt is the tangential velocity of air leaving the impeller ⁇ V .
  • angle of airfoil vanes 25 and 27 will depend upon the blade configuration (discussed below) and the rotational velocity of the impeller (i.e., the range of rotational velocity within which the blower is designed to operate) . It is desirable to match the leading edge of the airfoil to the direction of airflow encountering that leading edge, so that the angle of incidence is negligible. In general, air approaches envelope 24 at an angle of 20-30° from tangential in the regime described above.
  • Fig. 3 Superimposed on Fig. 3 is a vector diagram for flow V. entering the stator, in which V is the tangential swirl velocity entering the stator, and V is the axial velocity of the airstream entering the stator. V. is the tangential velocity of the blower wheel (impeller). Angle a_ 1 is 20-30° and angle ⁇ _ is 60-70°. Similar diagrams could be drawn for flow leaving stage 1 and entering stage 2, and for flow leaving stage 2. For flow V 2 leaving stage 2, the angle o_ 2 between v. - and V _ would be 80-90° and angle fl 2 is between 0° and 10°. The net effect is that V 2 ⁇ V-.
  • the diffusion factor is defined as (l-V 2 V 1 ) + ( v tl - v t2 > /2 ⁇ V i ' wh ere 7 -
  • V and V 2 are respective airflow velocities entering and leaving the stage, V . and V 2 are respective tangential velocities entering and leaving the stage, and ⁇ is blade solidity (i.e., blade chord ⁇ blade . spacing) .
  • Figs. 2A and 2B are cross-sectional representations " of the blades 14 and 15 of the invention, showing their "S" shape (i.e. their reverse camber). The blades are backwardly curved, and (given their relatively small size) develop large thrust or pressure, with good efficiency and low noise.- Specifically, Figs. 2A and 2B shows the "S" shape of long chord blades 14 and shorter chord auxiliary blades 15.
  • the suction side boundary layer must overcome three significant retarding forces: acceleration associated with the inertial reference frame curvature of the blade surface, a pressure gradient caused by the pressure rise that occurs from the blade leading edge to its trailing edge, and friction that exists at the blade-air interface. It is as though the air were rolling up hill; the air in the boundary layer begins its journey with a certain kinetic energy budget, which is partially dissipated by friction and partially converted into potential energy. At the same time the air follows a curved path, and the momentum change associated with this curvature thickens the boundary layer.
  • the blower design of the invention has a combination of high positive camber near the leading edge and apparent negative camber between midchord and the training edge.
  • the blade configuration of a centrifugal blower is selected using, among other things, knowledge of the following characteristics of blowers: l.
  • the pressure capacity of a blower increases as the square of the blade tip's tangential velocity at its outside diameter. This velocity is the product of diameter times rotation velocity.
  • the pressure - required by the application largely determines blower speed and diameter.
  • the pressure generated in the blading increases, in theory, to a maximum when the blade exit angle is 90 degrees, as shown in Fig. 4, However, the pressure observed experimentally reaches a maximum when the blade exit angle is still backward curved, at an angle of perhaps 50-60 degrees.
  • the 2-dimensional geometry of the blades defines a diffusion passage which has its largest total diffusion when the blade exit angle is 90 degrees. Boundary layer physics prevents realizing this maximum diffusion.
  • the velocity of the air discharged b 'the blower increases as the blade exit angle increases, and reaches a maximum at a blade exit angle well beyond 9*0 degrees.
  • the energy invested increases as the square of velocity. In applications where static pressure is ' required, it can be extracted from a high velocity discharge flow by diffusion.
  • the efficiency of the diffusion process is generally far higher in the blading. of the blower than in any process which diffuses the discharge flow—as high as 90 percent for the blading process, versus about 50 percent for the discharge process. It follows that the most efficient blower generally is the one which accomplishes the most diffusion in the blading. However, the blower blade design described herein accomplishes the combination of high efficiency along with small diameter and lower rotational velocity (leading to lower noise).
  • the blade entry angle is defined by the
  • Fig. 5 is a plot of local surface pressure (Cp) versus the blade chord position (designated as a percentage of total chord from 0 at the leading edge to
  • Cp ? s ⁇ l/2p (V t . p ) 2
  • the plot of Fig. 5 is based on a computer model of performance of the primary blades alone.
  • the lower plot represents local surface pressure on the suction surface
  • the upper plot represents local surface pressure on the pressure surface.
  • the overall work done is represented by the difference between the average pressure entering the blade (left axis, one-half way between the two plots) and the average pressure leaving the blade (right axis, convergence of the two plots).
  • the plot in Fig. 5 represents a flow of 240 CFM, a static pressure of 2.29 and a static efficiency of 0.46.
  • the "S" shaped blade of the invention pulls hard, as indicated in Fig. 5 by the ⁇ Cp from the high pressure side of the blade to the suction side of the blade, in the chord region 0.0-0.4. For the chord region 0.4-1.0, the blade does less work.
  • the blades have a high positive camber near the leading edge and a negative camber at some point between the mid-point and the tail - 11 -
  • the positive camber reaches a maximum of 1-3% in the leading half (e.g. 20-30%) of the blade, and the negative camber is 0.25%-3% in the trailing half (e.g. 70-80%) of the blade.
  • the operating regime of the blower is further defined by the flow number (J) and the pressure number (K. ) as follows:
  • n rotational velocity in revolutions/second
  • D diameter of the impeller in feet. Static pressure is measured in inches of water and is corrected to atmospheric pressure (29.92 inches Hg).
  • the flow number J is between 0.35 and 0.8 and the pressure number K. > 2.4.
  • the blade chord Reynolds number is 40,000 to 200,000. Blowers with these characteristics are less than 2 feet in diameter and preferably less than 12 inches.
  • the cross-sectional area of the outlet 15 of envelope 24 is larger (at least 1.2X) than the area of inlet area 13.
  • the increased area represents blade diffusion, since outlet 15 is filled with airflow.
  • the decreased inlet area significantly reduces noise.
  • the blower is manufactured by injection molding plastic, using e.g. fiber-filled plastic.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

L'invention concerne une soufflante centrifuge (10) courbée vers l'arrière comportant une enveloppe annulaire (24) située autour de la roue, de sorte de ladite roue rotative aspire de l'air dans une admission centrale et le force à sortir radialement dans ladite enveloppe et hors d'une décharge annulaire. Des pales (24, 27) multiples à profil d'aile sont positionnées dans l'enveloppe annulaire, dans deux étages déplacés axialement. Lesdites pales présentent un angle afin de tourner et de diffuser un flux d'air pénétrant dans l'enveloppe.
EP19900903670 1989-02-14 1990-02-05 Centrifugal fan with airfoil vanes in annular volute envelope Withdrawn EP0458880A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US310827 1981-10-13
US31082789A 1989-02-14 1989-02-14

Publications (2)

Publication Number Publication Date
EP0458880A1 true EP0458880A1 (fr) 1991-12-04
EP0458880A4 EP0458880A4 (en) 1992-02-12

Family

ID=23204280

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900903670 Withdrawn EP0458880A4 (en) 1989-02-14 1990-02-05 Centrifugal fan with airfoil vanes in annular volute envelope

Country Status (3)

Country Link
EP (1) EP0458880A4 (fr)
JP (1) JPH04505199A (fr)
WO (1) WO1990009526A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060093476A1 (en) * 2004-10-29 2006-05-04 Stanley Gavin D Fan stator
EP3015713A1 (fr) * 2014-10-30 2016-05-04 Nidec Corporation Appareil de soufflage
JP2016223432A (ja) * 2015-05-29 2016-12-28 日本電産株式会社 インペラ、送風装置、および掃除機
CN112879319A (zh) * 2019-11-29 2021-06-01 广东威灵电机制造有限公司 一种送风装置和吸尘器
CN113074137B (zh) * 2020-01-06 2023-06-09 广东威灵电机制造有限公司 送风装置及吸尘器
JP2022185276A (ja) * 2021-06-02 2022-12-14 株式会社デンソー 遠心送風機

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB689353A (en) * 1950-03-09 1953-03-25 Lysholm Alf Improvements in centrifugal compressors
FR1031705A (fr) * 1949-12-12 1953-06-25 Havilland Engine Co Ltd Perfectionnements aux compresseurs centrifuges
DE1024673B (de) * 1953-08-12 1958-02-20 Alois Mueller & Sohn G M B H M Radialgeblaese mit axialem Eintritt und Umlenkung der aus dem Laufrad austretenden Stroemung in einen axialen Ringkanal
FR1530533A (fr) * 1967-05-12 1968-06-28 Neu Sa Ventilateur centrifugo-axial
DE2403471A1 (de) * 1974-01-25 1975-07-31 Lwk Luft Waerme Klimatechnik G Lueftungsgeraet mit einem einseitig saugenden radialventilator
GB2080879A (en) * 1980-07-28 1982-02-10 Gebhardt Gmbh Wilhelm Flow guides for centrifugal fans

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2923461A (en) * 1953-04-27 1960-02-02 Garrett Corp Impulse axial-flow compressor
US3117770A (en) * 1961-04-19 1964-01-14 Crom B Campbell Combination air warming and centrifugal fan unit for transmitting heated air
US3584968A (en) * 1969-10-06 1971-06-15 Howard I Furst Fan construction
SE376051B (fr) * 1973-05-09 1975-05-05 Stenberg Flygt Ab
JPS51996A (en) * 1974-06-20 1976-01-07 Mitsubishi Heavy Ind Ltd Tetsukozaichuno ganjutansoryono bunsekihoho

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1031705A (fr) * 1949-12-12 1953-06-25 Havilland Engine Co Ltd Perfectionnements aux compresseurs centrifuges
GB689353A (en) * 1950-03-09 1953-03-25 Lysholm Alf Improvements in centrifugal compressors
DE1024673B (de) * 1953-08-12 1958-02-20 Alois Mueller & Sohn G M B H M Radialgeblaese mit axialem Eintritt und Umlenkung der aus dem Laufrad austretenden Stroemung in einen axialen Ringkanal
FR1530533A (fr) * 1967-05-12 1968-06-28 Neu Sa Ventilateur centrifugo-axial
DE2403471A1 (de) * 1974-01-25 1975-07-31 Lwk Luft Waerme Klimatechnik G Lueftungsgeraet mit einem einseitig saugenden radialventilator
GB2080879A (en) * 1980-07-28 1982-02-10 Gebhardt Gmbh Wilhelm Flow guides for centrifugal fans

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9009526A1 *

Also Published As

Publication number Publication date
JPH04505199A (ja) 1992-09-10
WO1990009526A1 (fr) 1990-08-23
EP0458880A4 (en) 1992-02-12

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