EP0690236A1 - Untwisted blade for axial-flow fan - Google Patents
Untwisted blade for axial-flow fan Download PDFInfo
- 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
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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
- F04D29/26—Rotors specially for elastic fluids
- F04D29/32—Rotors specially for elastic fluids for axial flow pumps
- F04D29/38—Blades
- F04D29/384—Blades characterised by form
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2240/00—Components
- F05B2240/20—Rotors
- F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
- F05B2240/301—Cross-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
- 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).
- 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.
- 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.
- 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.
- Figure 1 is a sectional view of
untwisted blade 1 of the type already known, equipped, along the trailing edge, withflag 3 sloped at a predetermined angle tobody 2 ofblade 1. At the junction betweenbody 2 andflag 3,blade 1 forms angle (or small-radius junction) atpoint 6, as clearly shown by the rather sharp direction change of mean line 8 (dashed line in Fig. 1) atsaid point 6. - Fig. 1 also shows
chord 4 ofbody 2 andwidth 7 offlag 3; only in somecases width 7 offlag 3 exceeds 30% of the length ofchord 4 ofbody 2 ofblade 1. - Figure 2 is a sectional view of
untwisted blade 1 according to the invention, equipped, along the trailing edge, withflag 3 sloped at a predetermined angle tobody 2 ofblade 1, said angle being usually equal to the inclination angle offlag 3 of the traditional blade (Fig. 1). -
Flag 3 is extensional to the mean line ofbody 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 betweenbody 2 andflag 3, gradually curves without any sharp direction change. - Fig. 2 also shows
chord 4 ofbody 2 andwidth 5 offlag 3;width 5 offlag 3 is in the range of 35% to 65% of the length ofchord 4 ofbody 2 ofblade 1 and, preferably, of 40% to 50% of the length of saidchord 4. - The advantages provided by a
flag 3 extensional to the mean line ofbody 2 ofblade 1 and by increasingwidth 5 offlag 3 without changing the dimensions ofbody 2 ofblade 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 ofbody 2 ofblade 1, while the improvement in blade performance may also be attributed to thelarger width 5 offlag 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.
- 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.
- 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 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)
- 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).
- 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).
- 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).
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 |
Family
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 |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0690236A1 (en) |
IT (1) | IT1271651B (en) |
Cited By (2)
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)
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 |
-
1994
- 1994-06-27 IT ITMI941334A patent/IT1271651B/en active IP Right Grant
-
1995
- 1995-05-29 EP EP95108151A patent/EP0690236A1/en not_active Ceased
Patent Citations (7)
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)
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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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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Effective date: 19960702 |
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17Q | First examination report despatched |
Effective date: 19970925 |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED |
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18R | Application refused |
Effective date: 19990718 |