EP0690236A1 - Untwisted blade for axial-flow fan - Google Patents

Untwisted blade for axial-flow fan Download PDF

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Publication number
EP0690236A1
EP0690236A1 EP95108151A EP95108151A EP0690236A1 EP 0690236 A1 EP0690236 A1 EP 0690236A1 EP 95108151 A EP95108151 A EP 95108151A EP 95108151 A EP95108151 A EP 95108151A EP 0690236 A1 EP0690236 A1 EP 0690236A1
Authority
EP
European Patent Office
Prior art keywords
blade
flag
blades
fan
axial
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.)
Ceased
Application number
EP95108151A
Other languages
German (de)
French (fr)
Inventor
Robert Mosiewicz
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.)
Cofimco SpA
Original Assignee
Cofimco SpA
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 Cofimco SpA filed Critical Cofimco SpA
Publication of EP0690236A1 publication Critical patent/EP0690236A1/en
Ceased legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/26Rotors specially for elastic fluids
    • F04D29/32Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38Blades
    • F04D29/384Blades characterised by form
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00Components
    • F05B2240/20Rotors
    • F05B2240/30Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F05B2240/301Cross-section characteristics

Definitions

  • the present invention relates to an untwisted blade for axial-flow fan (equipped, along the trailing edge, with a flag sloped to the blade body) which is less noisy and of higher performance than the blades already known.
  • Untwisted blades for axial-flow fan equipped, along the trailing edge, with a flag sloped to the blade body, are known to those skilled in the art (e.g. as disclosed in U.S. patent No. 4,618,313 by the Applicant).
  • the sloped flag width is in the range of 35% to 65% of the length of the blade body chord, and preferably of 40% to 50% of said length.
  • Figure 1 is a sectional view of untwisted blade 1 of the type already known, equipped, along the trailing edge, with flag 3 sloped at a predetermined angle to body 2 of blade 1. At the junction between body 2 and flag 3, blade 1 forms angle (or small-radius junction) at point 6, as clearly shown by the rather sharp direction change of mean line 8 (dashed line in Fig. 1) at said point 6.
  • Fig. 1 also shows chord 4 of body 2 and width 7 of flag 3; only in some cases width 7 of flag 3 exceeds 30% of the length of chord 4 of body 2 of blade 1.
  • Figure 2 is a sectional view of untwisted blade 1 according to the invention, equipped, along the trailing edge, with flag 3 sloped at a predetermined angle to body 2 of blade 1, said angle being usually equal to the inclination angle of flag 3 of the traditional blade (Fig. 1).
  • Flag 3 is extensional to the mean line of body 2 without forming angles or small-radius junctions, as shown by the curve of mean line 8 (dashed line in Fig. 2) that, at the junction between body 2 and flag 3, gradually curves without any sharp direction change.
  • Fig. 2 also shows chord 4 of body 2 and width 5 of flag 3; width 5 of flag 3 is in the range of 35% to 65% of the length of chord 4 of body 2 of blade 1 and, preferably, of 40% to 50% of the length of said chord 4.
  • the reduced noise and the higher efficiency of the fan may essentially be attributed to the flag 3 extensional to the mean line of body 2 of blade 1, while the improvement in blade performance may also be attributed to the larger width 5 of flag 3.
  • the test was conducted using a four-blade fan rotating at 600 r.p.m. in a 2 m dia. wind tunnel.
  • the value of the static pressure Ps (measured in kg/m2) was determined as a function of capacity Po (measured in m3/h x 1000).
  • curve 9 was obtained with a fan equipped with traditional blades and curve 10 with a fan equipped with the blades of the invention.
  • the cross-hatched area represents the performance improvement achieved with the claimed blades.
  • the test was conducted using a five-blade fan rotating at 960 r.p.m. in a 1.25 m dia. wind tunnel.
  • the sound pressure level SPL was measured in dB(A) with a phonometer the microphone of which is placed in a fixed position, 2 m from the rotating member centre.
  • Table 1 shows the sound pressure levels (SPL) (of a fan with traditional blades, respectively with the blades of the invention) for four different pitch settings and, for each pitch setting, for three different working conditions.
  • SPL sound pressure levels
  • the blades according to the invention allow a reduction in the sound pressure level by approx. 2 dB(A).
  • Power input was measured (in ampere) on a four-blade fan rotating at 600 r.p.m. in a 2 m dia. wind tunnel.
  • the test was repeated with different pitch settings, resetting the fan at an as nearly identical working condition as possible, defined by the total pressure Pt (measured in kg/m2) and dynamic pressure Pd (measured in kg/m2).
  • Table 2 shows the power input values for four different pitch settings and, for each pitch setting, for three different working conditions.

Abstract

A description is given of untwisted blade (1) for axial-flow fan, equipped, along the trailing edge, with flag (3) sloped to body (2) of blade (1), where said flag (3) is extensional to profile mean line of said body (2) of blade (1) and has a width (5) exceeding that of the flag of known blades.
Said new blade is less noisy and of higher performance than the blades already known.

Description

    Field of the invention
  • The present invention relates to an untwisted blade for axial-flow fan (equipped, along the trailing edge, with a flag sloped to the blade body) which is less noisy and of higher performance than the blades already known.
  • Prior art
  • Untwisted blades for axial-flow fan, equipped, along the trailing edge, with a flag sloped to the blade body, are known to those skilled in the art (e.g. as disclosed in U.S. patent No. 4,618,313 by the Applicant).
  • Said blades answered the intended purpose and were a commercial success.
  • Theoretical and experimental studies carried out by the Applicant provided evidence that the fan noise level could be further reduced and, at the same time, the blade performance and axial-flow fan efficiency could be improved by realizing said sloped flag extensional to the mean line of the blade body and by increasing the flag width.
  • Summary
  • It is an object of the present invention an untwisted blade for axial-flow fan equipped, along the trailing edge, with a flag sloped to the blade body, where the sloped flag is extensional to the mean line of said blade body.
  • The sloped flag width is in the range of 35% to 65% of the length of the blade body chord, and preferably of 40% to 50% of said length.
  • Brief description of the drawings
  • The present invention will now be described in greater detail, with reference to an exemplary embodiment as illustrated in the drawings, to which the present invention is not intended to be confined. In the drawings,
    • Fig. 1 is a sectional view of a known blade;
    • Fig. 2 is a sectional view of a blade according to the invention;
    • Fig. 3 is a graph illustrating the characteristic curves for a fan equipped with traditional blades and, respectively, with blades according to the invention.
    Detailed description
  • Figure 1 is a sectional view of untwisted blade 1 of the type already known, equipped, along the trailing edge, with flag 3 sloped at a predetermined angle to body 2 of blade 1. At the junction between body 2 and flag 3, blade 1 forms angle (or small-radius junction) at point 6, as clearly shown by the rather sharp direction change of mean line 8 (dashed line in Fig. 1) at said point 6.
  • Fig. 1 also shows chord 4 of body 2 and width 7 of flag 3; only in some cases width 7 of flag 3 exceeds 30% of the length of chord 4 of body 2 of blade 1.
  • Figure 2 is a sectional view of untwisted blade 1 according to the invention, equipped, along the trailing edge, with flag 3 sloped at a predetermined angle to body 2 of blade 1, said angle being usually equal to the inclination angle of flag 3 of the traditional blade (Fig. 1).
  • Flag 3 is extensional to the mean line of body 2 without forming angles or small-radius junctions, as shown by the curve of mean line 8 (dashed line in Fig. 2) that, at the junction between body 2 and flag 3, gradually curves without any sharp direction change.
  • Fig. 2 also shows chord 4 of body 2 and width 5 of flag 3; width 5 of flag 3 is in the range of 35% to 65% of the length of chord 4 of body 2 of blade 1 and, preferably, of 40% to 50% of the length of said chord 4.
  • The advantages provided by a flag 3 extensional to the mean line of body 2 of blade 1 and by increasing width 5 of flag 3 without changing the dimensions of body 2 of blade 1, were checked experimentally.
  • Measurements of static pressure Ps (a significant parameter for estimating blade performance), of sound pressure level SPL (correlated with noise) and of power input (correlated with fan efficiency) gave the results reported hereinafter.
  • In particular, the reduced noise and the higher efficiency of the fan may essentially be attributed to the flag 3 extensional to the mean line of body 2 of blade 1, while the improvement in blade performance may also be attributed to the larger width 5 of flag 3.
  • Furthermore, the performance of the blades according to the invention being higher, fans consisting of a lower number of blades may often meet the clients' specific requirements and obviously be economically advantageous.
  • Static pressure Ps
  • The test was conducted using a four-blade fan rotating at 600 r.p.m. in a 2 m dia. wind tunnel. The value of the static pressure Ps (measured in kg/m²) was determined as a function of capacity Po (measured in m³/h x 1000).
  • The results are plotted in Fig. 3: curve 9 was obtained with a fan equipped with traditional blades and curve 10 with a fan equipped with the blades of the invention.
  • The cross-hatched area represents the performance improvement achieved with the claimed blades.
  • The test was repeated using fans with different numbers of blades and blades of different diameters. The results obtained are analogous to those illustrated in Fig. 3.
  • Sound pressure level SPL
  • The test was conducted using a five-blade fan rotating at 960 r.p.m. in a 1.25 m dia. wind tunnel. The sound pressure level SPL was measured in dB(A) with a phonometer the microphone of which is placed in a fixed position, 2 m from the rotating member centre.
  • For both types of blades (traditional, respectively according to the invention) the test was repeated with different pitch settings (incidence angles of the blades), resetting the fan at an as nearly identical working condition as possible, defined by the total pressure Pt (measured in kg/m²) and dynamic pressure Pd (measured in kg/m²).
  • Table 1 shows the sound pressure levels (SPL) (of a fan with traditional blades, respectively with the blades of the invention) for four different pitch settings and, for each pitch setting, for three different working conditions.
  • As may be noticed, the blades according to the invention allow a reduction in the sound pressure level by approx. 2 dB(A).
  • Said test was repeated using fans with different numbers of blades and blades of different diameters. The results obtained are analogous to those illustrated in Table 1. TABLE 1
    Fan with traditional flag Fan with new flag
    Pt Pd SPL Pt Pd SPL
    13.8 11.7 89.2 14.0 71.6 87.2
    21.6 9.4 91.0 21.4 9.5 89.1
    31.7 6.8 96.2 32.0 6.6 93.5
    21.4 18.0 87.0 21.7 18.0 85.5
    29.8 15.4 87.0 30.0 15.5 84.9
    40.7 10.5 93.0 41.0 11.0 82.0
    30.7 26.4 86.0 31.0 26.3 84.0
    46.0 18.7 88.5 47.0 18.7 86.0
    55.0 11.4 92.4 54.2 12.8 90.0
    41.0 35.0 85.8 42.2 35.2 85.0
    66.0 20.0 88.0 66.4 19.5 85.5
    72.0 12.0 91.0 73.0 12.1 89.5
  • Power input
  • Power input was measured (in ampere) on a four-blade fan rotating at 600 r.p.m. in a 2 m dia. wind tunnel. For both types of blades (traditional, respectively according to the invention) the test was repeated with different pitch settings, resetting the fan at an as nearly identical working condition as possible, defined by the total pressure Pt (measured in kg/m²) and dynamic pressure Pd (measured in kg/m²).
  • Table 2 shows the power input values for four different pitch settings and, for each pitch setting, for three different working conditions.
  • As shown in said table, under all working conditions, the blades according to the invention allow a reduction in the power required by the fan. TABLE 2
    Fan with traditional flag Fan with new flag
    Pt Pd A Pt Pd A
    9.0 7.5 21.5 3.0 1.7 21.5
    16.4 5.2 23.0 16.5 5.5 22.5
    23.0 2.7 23.5 13.0 2.9 23.2
    14.2 12.4 30.5 14.5 12.5 30.0
    19.5 9.6 32.5 19.1 9.5 32.3
    28.5 5.4 33.5 29.0 5.0 33.1
    19.6 17.0 48.0 19.9 17.0 48.0
    28.0 11.0 48.5 27.8 11.5 48.0
    31.0 9.0 48.0 31.0 9.8 47.8
    23.0 19.8 65.0 22.5 20.0 64.6
    28.0 15.5 65.0 28.2 15.5 64.0
    35.0 9.2 61.0 36.0 9.5 62.0
  • All modifications of and improvements in untwisted blade for axial-flow fan as suggested by experience and by the natural evolution of the technique may be effected by those skilled in the art without departing from the scope of the invention.

Claims (3)

  1. Untwisted blade for axial-flow fan, equipped, along the trailing edge, with a flag sloped to the body of said blade, characterized in that said sloped flag (3) is extensional to the mean line (18) of body (2) of said blade (1).
  2. The blade according to claim 1, characterized in that width (5) of said sloped flag (3) is in the range from 35% to 65% of the length of chord (4) of said body (2) of said blade (1).
  3. The blade according to claim 2, characterized in that width (5) of said sloped flag (3) is in the range from 40% to 50% of the length of chord (4) of said body (2) of said blade (1).
EP95108151A 1994-06-27 1995-05-29 Untwisted blade for axial-flow fan Ceased EP0690236A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI941334 1994-06-27
ITMI941334A IT1271651B (en) 1994-06-27 1994-06-27 UNCHANGED SHOVEL FOR AXIAL FAN

Publications (1)

Publication Number Publication Date
EP0690236A1 true EP0690236A1 (en) 1996-01-03

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ID=11369171

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95108151A Ceased EP0690236A1 (en) 1994-06-27 1995-05-29 Untwisted blade for axial-flow fan

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EP (1) EP0690236A1 (en)
IT (1) IT1271651B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007107489A1 (en) * 2006-03-23 2007-09-27 Valeo Systemes Thermiques Fan propeller, in particular for motor vehicles
CN101666329B (en) * 2009-09-17 2012-02-01 上海交通大学 Combined-wing type axial flow fan blade

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1205472A (en) * 1957-04-16 1960-02-03 Improvements in paddlewheels, propellers and the like to produce axial effects, more particularly axial air flow
GB909544A (en) * 1960-06-24 1962-10-31 Ottis David Twist Fan
DE2112261A1 (en) * 1971-03-13 1972-09-14 Battelle Institut E V Cooling fan
US3825369A (en) * 1972-09-13 1974-07-23 Hayes Albion Corp Lightweight fan
US4618313A (en) 1980-02-06 1986-10-21 Cofimco S.R.L. Axial propeller with increased effective displacement of air whose blades are not twisted
US4892460A (en) * 1989-01-30 1990-01-09 Volk Steve J Propeller breeze enhancing blades for conventional ceiling fans
WO1992001865A1 (en) * 1990-07-26 1992-02-06 Howden Wind Turbines Ltd. Wind turbine blade and rotor incorporating same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1205472A (en) * 1957-04-16 1960-02-03 Improvements in paddlewheels, propellers and the like to produce axial effects, more particularly axial air flow
GB909544A (en) * 1960-06-24 1962-10-31 Ottis David Twist Fan
DE2112261A1 (en) * 1971-03-13 1972-09-14 Battelle Institut E V Cooling fan
US3825369A (en) * 1972-09-13 1974-07-23 Hayes Albion Corp Lightweight fan
US4618313A (en) 1980-02-06 1986-10-21 Cofimco S.R.L. Axial propeller with increased effective displacement of air whose blades are not twisted
US4892460A (en) * 1989-01-30 1990-01-09 Volk Steve J Propeller breeze enhancing blades for conventional ceiling fans
WO1992001865A1 (en) * 1990-07-26 1992-02-06 Howden Wind Turbines Ltd. Wind turbine blade and rotor incorporating same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007107489A1 (en) * 2006-03-23 2007-09-27 Valeo Systemes Thermiques Fan propeller, in particular for motor vehicles
FR2898943A1 (en) * 2006-03-23 2007-09-28 Valeo Systemes Thermiques FAN PROPELLER, ESPECIALLY FOR AUTOMOTIVE VEHICLES
US8186957B2 (en) 2006-03-23 2012-05-29 Valeo Systemes Thermiques Fan propeller, in particular for motor vehicles
CN101427030B (en) * 2006-03-23 2013-01-23 法雷奥热系统公司 Fan propeller, in particular for motor vehicles
CN101666329B (en) * 2009-09-17 2012-02-01 上海交通大学 Combined-wing type axial flow fan blade

Also Published As

Publication number Publication date
IT1271651B (en) 1997-06-04
ITMI941334A0 (en) 1994-06-27
ITMI941334A1 (en) 1995-12-27

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