CN1060895A

CN1060895A - The blade of a kind of high coefficient of lift combined, high lift-drag ratio

Info

Publication number: CN1060895A
Application number: CN 90102959
Authority: CN
Inventors: 徐咏明
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-10-16
Filing date: 1990-10-16
Publication date: 1992-05-06

Abstract

The blade of a kind of industrial fan and household fan, adopted and had boundary layer airflow the BZK structure and the WZ device that can control the air-flow whirling motion of wing tip district of control automatically, the big sweepforward angle design of having adopted heavy camber to reverse simultaneously, thereby make blade obtain big available lift coefficient CL and higher ratio of lift coefficient to drag coefficient L/D, have excellent usability, dwindling the blade span size to energy-saving and noise-reducing or under the same effect condition has positive effect.

Description

The blade of a kind of high coefficient of lift combined, high lift-drag ratio

The invention belongs to industrial fan, the Blade Design that household fan is used is made the field.Long-term next restriction owing to the design and fabrication technological level, the blade of industrial fan, household fan is all continued to use the bent plate structure, generally all adopts the moulding of thin metal plate stamping.This blade by plank frame, its lift coefficient CL and ratio of lift coefficient to drag coefficient L/D value are all lower, and some blade profile design preferably is under the maximum lift-drag ratio situation, and its lift coefficient also can only reach about 1.4.(annotate: ratio of lift coefficient to drag coefficient L/D is the available lift coefficient CL value and the ratio of resistance coefficient CD) is well-known, a kind of blade profile of blade is weighed the sole criterion of its performance quality, look it exactly and whether have maximum ratio of lift coefficient to drag coefficient L/D, also promptly look it and whether have maximum available lift coefficient CL and as far as possible little resistance coefficient CD; Or do not have maximum available aerodynamic lift Y and as far as possible little aerodynamical resistance D.Therefore the structural behaviour of bent plate formula blade is very poor, and utilization efficiency is extremely low, and consumed energy is bigger.

Its theoretical calculation consumed power of blade P=ρ SCDV of certain structure shape ³; 1/2 wherein ρ be air density, S is the surface area of blade profile, CD is a resistance coefficient, V is the equivalent movement velocity of blade.Produce at blade under the situation of identical aerodynamic lift Y, according to bernoulli's equation as can be known, improve the movement velocity V that lift coefficient CL can reduce blade, the appearance structure size of perhaps dwindling blade, thus all can reach the purpose that reduces aerodynamical resistance D and reduce wasted work P.Therefore managing to improve the lift coefficient CL of blade and reduce resistance coefficient CD effectively is to obtain the blade maximum lift-drag ratio, improves performance, improves its working efficiency, the ten minutes important channel of energy saving.

The objective of the invention is in order to seek a kind of high coefficient of lift combined CL, the blade profile design of high lift-drag ratio L/D, make the industrial fan of blade in various rotation speed change, premium properties is arranged when using in the household fan, less parasitic drag, higher utilization efficiency in the hope of reaching the good result of energy-saving and noise-reducing, has the important techniques economic implications to the industrial fan that has a large capacity and a wide range and the application of household fan.

For achieving the above object, the present invention has done multinomial improvement on blade structure, has adopted following several novel designs, now is analyzed as follows:

1, shows from the existing achievement in research of aerodynamics, the air-flow of blade surface boundary layer is compared with the outer gas flow away from blade surface, its inertial force and momentum are less, the surface layer air-flow separates with blade airfoil easily in flow process, heavy camber particularly, high CL value blade profile is when daying horn shape condition, and this phenomenon is obvious still just.As above said aerofoil flow segregation phenomenon, original often laminar flow gas and then produce after the separation turbulent flow again attached to blade airfoil on, and turbulent layer thickness constantly increases, form an air stagnant wake that pressure is almost constant, the air stagnant wake that this pressure on the blade is constant also is called separate bubbles.Under the rational situation of the angle of attack, follow-up air-flow can be walked around separate bubbles and get back on the blade face again.The scope that separate bubbles extends on the blade face is big more, and then air-flow is walked around separate bubbles and returned position on the blade face the closer to vane trailing edge.When the angle of attack is certain certain value, separate bubbles always appears, and air-flow can't be crossed separate bubbles and laminar flow occur and separate when not returning on the blade face, will cause blade stall, and resistance heightens, and efficient obviously reduces.Available research achievements shows that also resistance coefficient is directly proportional with the distance of stalling point position to trailing edge, and the size of blade lifting resistance ratio L/D value depends on the distance of separation point to trailing edge to a great extent.For this reason, as long as manage to increase the extend to scope of separate bubbles on the blade face, just can postpone the distance of separation point, thereby can improve the pressure distribution of blade surface effectively, reduce resistance, improve the value that lift is counted CL and ratio of lift coefficient to drag coefficient L/D to trailing edge.

The present invention is according to as above analysis, adopted a kind of structure (being designated hereinafter simply as the BZK structure) that can realize that boundary layer airflow is controlled automatically, be depicted as the blade cross section of BZK structure as figure one, it is characterized in that by the cavity III in the wing and blade upper surface leading edge one row's aperture φ ₁And trailing edge one row's macropore φ ₂Form; Figure two has shown φ ₁And φ ₂The size of two rounds and distributing position feature, front-seat aperture φ ₁Diameter be generally 1.0-3.0MM, between its hole is 15-35MM apart from a, its size C apart from the leading edge I is 3-8%l; (wherein l is that wing string is wide), back row's macropore φ ₂Diameter be that its size d apart from leading edge of 3.0-9.0MM generally is 80%l, and the distance b between the hole is 25-55MM; The sectional area of the front-seat aperture of sectional area ratio of back row's macropore is advisable for big about three times, and wing inner cavity size is to satisfy intensity, under the rigidity condition, it is bigger for well to try one's best, to help absorbing the whirling motion air-flow from macropore, and freely emerge from front-seat aperture by inner chamber, the air-flow of emerging can make the separate bubbles expanded range, formation is to the transformation of turbulent boundary layer, along with the increase of the angle of attack, aerofoil profile leading edge air velocity increases, and the suction capactity of front-seat aperture strengthens, the ability that absorbs the whirling motion air-flow from back row's macropore is also just more remarkable, thereby can significantly enlarge the scope of separate bubbles,, improve the performance of blade to improve lift coefficient.Yet the quantity of front and back round, aperture, pitch-row and apart from the size of leading edge all will be according to aerofoil profile, movement velocitys, and the blade profile global shape could determine after weighing consideration comprehensively, also can choose optimum value by test certainly.

2,,,, raising CL value become one of energy-conservation ten minutes key issue so must managing to reduce induced drag simultaneously because the raising of CL and the increase of induced drag have very confidential relation for the blade that has wing tip.

Induced drag claims vortex drag again, is to be caused by a kind of air-flow that rotates whirling motion.The reason that it produces is when producing lift owing to blade, to have pressure difference between the upper and lower surface of blade, and near the lower surface high-pressure air the wing tip district will be walked around wing tip and flow to the low pressure area of upper surface.Therefore can form one resupinate air-flow backward in the outside in wing tip district and along wing tip, this phenomenon is called usually washes, shown in figure three, and from the nose of wing I backward flow air in the therefore and slightly outside deflection of lower surface, and wash under forming, wash like this and cross into the whirling motion of eddy current downstream after following gas washing flows to, shown in figure four.The existence in wing tip whirlpool does not only produce useful lift, also changed the direction of whole air-flow, press air-flow whirling motion intensity difference disturbance pro rata whole air flow system, induced drag as whole pneumatic reaction force component, point to the reverse formation resistance of blade movement with the direction of air-flow whirling motion, the CL value is big more, and whirling motion intensity is also big more, derivative coefficient and induced drag are also just big more, and its harm might be offset CL and improve the benefit of being brought.

According to as above analyzing, can not produce induced drag if there is the wing tip whirlpool just to exist, and if make the transverse motion components of blade lower surface air-flow controlled, just can control the generation in downwash and wing tip whirlpool, thereby eliminate or reduce induced drag effectively, to improve Blade Properties.

The present invention adopts eddy current to control system's (hereinafter to be referred as WZ device), its structure characteristic is to have added some curved baffles on the trailing edge appropriate location, following blade face in wing tip district, curved baffle generally is positioned on the concentric garden of blade garden week moving direction, by the parallel distribution of equi-spaced apart, form the effect of air-flow duct in the time of so blade movement can being made, prevent down the transverse movement of blade face air-flow effectively, hinder the upwards upset of wing tip air-flow, shown in figure five.The shape and size optic lobe plate shape of baffle plate and size and decide, shown in figure six, figure seven, the X face is a baffle plate and the link surface on following blade face, the shape of the following blade face of its surface configuration phase junction and deciding; Length dimension E is the 30-40% of blade wing chord width l, height dimension H is the 60-80% of following blade face flow boundary layer air thickness, figure seven is the A-A section among the figure six, wherein angle, garden r1, r2 and lateral width δ are in principle to guarantee under enough strength and stiffness conditions, the smaller the better, in the hope of reduce as far as possible because of other loss that the WZ device brings, size e=r1+r2 are installed; The quantity of baffle plate is determined with actual effect; The baffle plate rear end is alignd consistent with trailing edge substantially.

3, the stall of blade says to be exactly that laminar flow separates the consequence that causes that pressure drag increases in essence, for heavy camber, and the aerofoil profile of high CL value, this phenomenon is just more outstanding; And for the industrial fan and the household fan of movement velocity range, this heavy camber, although the Blade Design of high CL value has adopted the BZK structure, under the low cruise state, blade tip still can produce the stall phenomenon.

Tip stall problem when solving the blade low cruise, the present invention is adopting on aforementioned BZK, the WZ architecture advances basis, blade to heavy camber, high CL value has used big sweepforward angle design, and will be according to the blade movement velocity range, promptly according to industrial fan and household fan different characteristics of reynolds' number when the different rotating speeds scope is worked, adopt different sweepforward angle designs, the amplitude range that sweepforward angle changes is generally 11 °-38 °.Adopted the blade of sweepforward angle design, it is less to the influence of the pressure distribution on the blade when the sweepforward angle is less, then influence increased to the pressure distribution on the blade when sweepforward angle was big, tip stall in the time of can not only controlling low speed effectively, big sweepforward angle can not produce adverse consequences yet when high speed operation, and like this, big sweepforward angle design can obtain high CL value effectively in the heavy camber blade, obtain the operating speed scope widened again simultaneously, improved the usability of blade greatly.

In sum, the blade that adopts BZK, WZ and sweepforward to reverse in conjunction with heavy camber has excellent performance and energy-saving and noise-reducing effect:

1, the utilization of BZK structure, improved the pressure distribution on blade face, blade is being increased under the resistance coefficient CD situation hardly, made available lift coefficient CL reach 5-7, thereby greatly having improved ratio of lift coefficient to drag coefficient L/D value, this is inconceivable for general common bent plate formula blade.

2, the utilization of BZK structure moves blade under precritical low reynolds number state, can keep laminar flow not separate, and the stable operation that when high CL value, can keep subcritical low speed, having overcome laminar flow separates the blade stall that causes, resistance heightens, the serious drawback that efficient reduces.

3, WZ system and BZK structure all produce induced drag to the transverse movement of air-flow and the air-flow whirling motion that causes has and significantly controls effect, to improving Blade Properties, reduces aerodynamic noise, reduces loss, and raising the efficiency all has obvious effect.

4, the blade profile of heavy camber can obtain higher CL value, owing to after having adopted big sweepforward angle design, solved the low speed problem again, thereby enlarged the operating speed scope of blade, and make it have the superperformance of stable operation in high CL value and the wide fast scope.

Below legend is further specified as follows:

Figure is just like the preceding sectional elevation of having stated to the BZK structure, and I is the air-flow stationary point, and (vertically constitute the leading edge of blade, II is the afterbody of wing chord, vertically constitutes vane trailing edge, φ in the span in the span ₁Be front-seat aperture, φ ₂Be back row's macropore, III is a cavity, and IV is to adhere to the turbulent layer on blade face, and its thickness constantly increases and then further forms separate bubbles.Outer gas flow around the blade is a laminar condition, and the aerodynamic angle of incidence of blade is α.

Second figure has shown further that the external form of BZK structure and hole system distribute.Figure three is for existing the blade end structure of the protruding dew of wing tip, and A is the zone of high pressure among the figure, and B is a low pressure area, and I is a leading edge, and II is a trailing edge, and O-O is a whirling motion air-flow whirlpool axle.Figure four has illustrated the further consequence of air-flow whirling motion among the figure three, and L is a blade span length, and expression air-flow in a place is washed on taking place, and b place is for washing down, and c place expands for washing the past downstream of back formation eddy current continuation that crosses up and down, make actual span length L '＜L.Figure five is the schematic representation of WZ device change air-flow lateral flow, and figure six, figure seven have further shown the concrete shape and the structure of WZ curved baffle, and wherein figure seven is the A-A sectional drawing among the figure six.As follows below in conjunction with embodiment's marginal data:

Figure eight is the external form stereogram of the Application Example of the present invention in the family expenses ceiling fan, this embodiment's concrete structure size is seen figure nine figure ten (1), (2) and figure 11, shown in figure 12 each figure, wherein figure nine is the plane figure of present embodiment, the swing diameter D=1200mm that figure wing centre section spread becomes, and A is the WZ system, having three groups of curved baffles forms, its distribution radius is respectively R1=550mm, R2=500mm, R3=450mm.B is the front and back round system in the BZK system among the figure, the somatotype diameter D1=600mm that the turning point of blade sweepforward forms, this turnover somatotype diameter is divided into inner region I and outskirt II to blade, aperture, the pitch-row of each functional hole of BZK front and rear row in inner region I and outskirt II are all different, and now contrast figure two and figure nine list in table one with each size

Table one

Wherein l still is the preceding wide size of aerofoil profile string of having stated.

The concrete size of WZ system baffle plate is seen figure ten (1) and (2), and wherein length unit is mm.

Figure 11 expressions constitute each parameter and root of blade each parameter behind over commutation of sweepforward angle.

The actual angle of attack that forms in the different cross section place after the figure 12 expression blade twists, angle of attack β=17 at nearly blade root place °, angle of attack α=3 at end of blade place °.

Vane airfoil profile is to be fundamental mode in conjunction with adopting BZK structure of the present invention with the NACA6409 type in the present embodiment, WZ system and sweepforward heavy camber are reversed to improve and are designed, blade material can adopt thin metal sheet material or the moulding of ABS engineering plastics, the ceiling fan performance is better than conventional bent plate structure ceiling fan, its rotating speed is applicable to 180-500 rev/min of scope, power when diameter is 1200mm＜60 watt.Embodiment 2 is a 600mm industrial fan blade, and figure 13 is its front projection figure, and complete machine is made of six leaves, figure 14 is a cowling for plan view I wherein, and II is the leaf dish, only keeps a slice blade among the figure, the angle of attack of end of blade shown in figure α=38 °, blade root angle of attack β=71 °.Figure 15 is the plane outspread drawing of its blade, blade chord length l=120mm, sweepforward angle θ=20 °.BZK structure and size in the present embodiment are seen figure 16, figure 17 and table two.

The mm of table two unit

The position, hole		The hole site
				a	R125	a	R125
a′	R145	b	R160
				b′	R165	c	R195
c′	R185	d	R230
				d′	R205	e	R265
e′	R225	f	R290
				f′	R245	/	/
g′	R265	/	/
				h′	R285	/	/

Visible φ among the figure 17 ₁=φ 1.6mm φ ₂=φ 6.5mm

φ ₁Apart from the size c=6mm of leading edge, φ ₂Size d=96mm apart from leading edge.Figure 17 being seen aerofoil profiles are in conjunction with adopting BZK structure of the present utility model to form on Sawyer aerofoil profile basis, the three-dimensional outline drawing of the embodiment that figure 18 uses on ZJ-60 type blower fan for blade of the present invention, blower fan duct and support etc. do not draw among the figure, rated speed is 1450 rev/mins in the present embodiment, and air mass flow is 20000 meters ³/ hour, air stream is penetrated apart from being under 20 meters the running parameter condition, its power demand＜2.4KW, and descending than original 2.8KW can 14.3%.Present embodiment needs only replacing motor and fan blade to the blower fan of φ 600mm diameter, and keeps former duct and support, all can carry out transformation easily, and can receive tangible techno-economic effect.

Claims

1, the blade of a kind of industrial fan and household fan, feature of the present invention are that front-seat aperture φ 1 and back row's macropore φ 2 common boundary layer airflow of forming with wing inner cavity III and blade upper surface are controlled the BZK structure automatically; On the trailing edge appropriate location, following blade face in blade tip district, add some curved tailgates and formed the WZ device of controlling the air-flow whirling motion of wing tip district; And the big sweepforward angle design of having adopted heavy camber to reverse.

2, the blade of industrial fan according to claim 1 and household fan, feature of the present invention are front-seat aperture φ; Diameter is generally 1.0-3.0MM, and distance between borehole a is 15-35MM, and it is the 3-8% of wing chord width l apart from leading edge size C; Back row's macropore φ ₂Diameter be generally 3.0-9.0MM, distance between borehole b is 25-55MM, and generally is 80% of wing chord width l apart from leading edge size d.

3, industrial fan according to claim 1 and household fan blade, feature of the present invention are that curved baffle generally is positioned on the blade garden week moving direction concentric circle, by the parallel distribution of equidistant intervals.

4, the blade of industrial fan according to claim 1 and household fan, feature of the present invention are that the sweepforward angle θ that blade adopts is 11 °-38 °.

5, according to the blade of described industrial fan of claim 1.2 and household fan, feature of the present invention is the inner region I at blade, front-seat aperture φ ₁Diameter be 1.4mm, hole pitch a=22mm is apart from leading edge size C=5%l; Back row's macropore φ ₂Diameter be 5.8mm hole pitch b=40mm, apart from leading edge size d=80%l, in the outskirt II of blade, front-seat aperture φ ₁Diameter be 1.8mm, hole pitch a=28mm is apart from leading edge size C=5%l; Back row's macropore φ ₂Diameter be 6.2mm, hole pitch b=43mm is apart from leading edge size d=80%l.

6, according to the blade of claim 1,2 described industrial fans and household fan, feature of the present invention is φ ₁The diameter in hole is 1.6mm, φ ₂The diameter in hole is 6.5mm, hole φ ₁Spacing a=20mm, φ ₂The spacing in hole except that wing tip district outermost end two hole pitch b=25mm, all the other hole pitch b=35mm, φ ₁Pitch-row leading edge size C=6mm, φ ₂Pitch-row leading edge size d=96mm.

7, press the blade of claim 1,3 described industrial fans and household fan, feature of the present invention is that curved baffle x face shape is fixed with the shape of blade face junction under the blade, its length E is the 30-40% of blade wing chord width l, and height H is the 60-80% of following blade face flow boundary layer air thickness.

8, according to the blade of claim 1,4 described industrial fans and household fan, feature of the present invention be sweepforward angle θ=20 ° of blade or θ=17 ° 41 '.

9, according to the blade of claim 1,5 described industrial fans and household fan, feature of the present invention is the length E=50MM of curved baffle, height H=7MM.