Radial vane swirl generator

Improved radial vanes of a swirl generator, which are rotatably radially disposed at the fluid outlet of a bellow, wherein a handle device is used to make the radial vanes rotate within 0-80 range for adjusting the air swirl intensity required by the burner, the fluid flowing through the vanes to directly coil into the combustion chamber so as to avoid the drawbacks of high pressure drop and high turbulent flow intensity occurring at the inlet of a burner.

BACKGROUND OF THE INVENTION 
The present invention relates to a radial vane swirl generator, and more 
particularly to rotatable radial vanes of a swirl generator. 
A burner is one of the most important parts in the combustion system. The 
capability of the burner not only has great influence on the combustion 
efficiency but also closely relates to the stability of the flame, the 
effective application of the fuel and the discharge of pollutant. 
Improper combustion technology and improper selection of burners not only 
influences the effective use of energy, but also results in air pollution 
due to emitting large amount of hazardous material by combustion. 
Conventional burner applies a fan or a compressor to send the air into the 
combustion chamber to mix with the fuel for burning. The blades of such 
conventional burner are of fixed radial type. The practicians often apply 
low-excess-air combustion technics to industrial boiler. Moreover, by 
means of fuel gas recirculation, the peak temperature of flame can be 
reduced to control thermal-NO. Swirling flow generated by 
properly-designed swirl generator and fuel-gas recirculation can control 
the residence time of combustion gas and flame temperature so that 
controlling fuel-rich combustion, reducing peak temperature of flame, 
controlling residence time of combustion gas and partial fuel-rich 
combustion and increasing stability of flame are several important keys of 
advanced burner design. 
When air flows through the fixed radial flow-guiding vanes to form swirling 
flow, if the pressure drop and turbulent intensity are too high, then the 
capability of the burner will be poor, and the flow-guiding vanes are 
fixed so that the swirl intensity thereof is fixed and can not be adjusted 
in accordance with combustion state to achieve a best combustion 
condition. 
Therefore, a good swirl generator must have changeable swirl flow so as to 
achieve low pressure drop, low turbulent intensity and be capable of 
producing desired recirculation intensity and controlling partial 
fuel-rich combustion, lowering peak temperature, controlling residence 
time of combustion gas and increasing flame stability. 
The swirler of this invention can produce swirling flow to change the speed 
of air flow and deflect the radial incoming flow to produce a divisional 
angular vector. The swirling air flow then passes through expansion 
quarrel to form the recirculation. 
Generally, there are three manners of generating swirling flow field: 
1. manner of tangential entry; 
2. manner of guided vanes; and 
3. manner of rotating pipe. 
In this invention, radial vanes are used to produce required swirling flow 
field. 
When the swirling flow passing through combustion chamber, bluff body and 
expansion chamber, the swirling air flow will create reverse pressure 
gradient to form a recirculation zone. Not only is fuel vigorously mixed 
with air around this recirculation zone, but also a portion of the hot 
combustion product gas is recirculated back to sustain proper ignition, 
thereby assuring flame stability. 
Swirling flow has the good quality of increasing flame stability. The 
proper swirling flow generated by properly-designed swirl generator can 
control flame, maintain fuel-rich combustion, reduce peak temperature of 
flame, control residence time of combustion gas, inhibit creation of 
pollutant. 
The radial vanes of this invention is designed to achieve swirl level under 
the lowest pressure drop and the lowest turbulent intensity. The rotatable 
radial vanes of this invention are capable of decreasing the pressure drop 
and turbulent intensity. The proper rotary angle of the radial vanes is 
within a 0-80 range to give a tangential momentum to radially guided flow 
and the swirl intensity can be changed following the rotary angle of the 
vanes to achieve a circulation zone for enhancing the stability of the 
flame. 
SUMMARY OF THE INVENTION 
It is a primary object of this invention to provide a swirl generator with 
rotatable radial vanes the rotary angle of which is within a 0-80 range to 
produce changeable swirl intensity so as to prevent high pressure drop and 
high turbulent flow and achieve the objects of more complete combustion, 
good mixing, high efficiency and low pollution, etc. 
The present invention can be best understood through the following 
description and accompanying drawings wherein:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Please refer to FIGS. 1 and 6, wherein the bellow 100 of this invention 
includes a cylindrical housing 10, adapted to be fitted in an air pathway 
to a combustion chamber, having a first end, a second end, a central 
portion and an air inlet, an inner board 50 having a central hole, an 
outer board 60 also having a central hole, a beehive board 11 also having 
a central hole, a central shaft holding block 30, a biasing block 40 and 
radial vane mechanism 20. The inner board 50 and outer board 60 are 
respectively fitted to two ends of the cylindrical housing 10. The beehive 
11 is welded at middle portion of the housing 10. Multiple vent holes 111 
are formed on the beehive board 11 for the air flow to go therethrough. 
The radial vane mechanism 20 goes through the central holes of the inner 
board 50, beehive board 11 and outer board 60 and extend throughout the 
central portion of the housing 10 to be supported and fixed thereon. Two 
ends of the radial vane mechanism 20 are engaged with the central holes of 
the inner board 50 and outer board 60 respectively by means of the central 
shaft holding block 30 and biasing block 40. 
Please now refer to FIGS. 1, 3A and 3B, wherein the central shaft holding 
block 30 is a sleeve-like controlling block the outer circumference of 
which is associated with a sleeve 32 so as to engage with the inner board 
50. The central shaft holding block 30 has an outer flange portion 33 
formed with two opposite thread holes 34, 36 whereby two handles 31 are 
secured in the thread holes 34, 36 of the flange portion 33 so as to 
fasten the holding block 30 to the sleeve 32. The holding block 30 is 
further fixed with a rotary sleeve 21 by pin members 35. 
Please now refer to FIGS. 2, 4A, 4B, 5A, 5B, 8A, 8B, wherein the radial 
vane mechanism 20 includes the fixing disk 25, drive disk 22, central 
shaft 24, rotary sleeve 21, wheel seat 26, rotary disk 28 and multiple 
identical radial vanes 23. The radial vane mechanism 20 is disposed in the 
central portion of the bellow 100. The central shaft 24 goes through the 
rotary sleeve 21. Inside the central shaft 24 are disposed fuel-spraying 
system and ignition system. One end of the rotary sleeve 21 is engaged 
with the central shaft holding block 30 located on the inner board 50 
while the other end thereof is engaged with the rotary disk 28 located 
beside the drive disk 22. The wheel seat 26 and drive disk 22 is 
associated with the fixing disk 25 located on the outer board 60 by means 
of several pin members 261. The fixing disk 25 is formed with pin holes 
262 for the pin members 261 to engage therewith. Between the drive disk 22 
and fixing disk are disposed a plurality of radial vanes. 
A plurality of same size pulleys 27 are fixed on the drive disk 22, the rim 
of the pulleys 27 are inserted in a grove 263 of the wheel seat 26. A 
plurality of vane shaft holes 235 are formed in the wheel seat 26 for the 
vane shaft 233 to be disposed therein. The other end of the vane shaft 233 
is inserted in the vane shaft hole 224 of the fixing disk 25. The radial 
vane 23 is disposed on the vane shaft 233. A guide wheel pin 232 is 
disposed on lateral side of an upper portion 234 of the radial vane 23. A 
guide wheel 231 is disposed on the guide wheel pin 232 and located in a 
guide wheel groove 221 of the drive disk 22. The rotary disk 28 is 
connected with the drive disk 22 by bolts 281. When the rotary sleeve 21 
rotates, the rotary disk 28 and drive disk 22 are driven to rotate by 
means of the support and roll of the pulleys. At this time, the guide 
wheel 231 slides along the guide wheel groove 221, making the radial vane 
23 included by a certain angle, i.e., the radial vane 23 can be radially 
seen to change within 0-80 range. The incoming air flow goes through the 
inner portion of the housing 10 from air inlet 51 and goes into the upper 
end of the radial vane 23. The inclined radial vane 23 will swirl the air 
flow to be sent out from the biasing block 40. The angle of the radial 
vane 23 can be adjusted according to required swirl intensity. 
Please now refer to FIGS. 1, 2, 3A, 3B, 4A and 4B, wherein when the handle 
31 rotates the central shaft holding block 30, the rotary sleeve 21 of the 
radial vane mechanism 20 is driven, through the rotary disk 28 wheel seat 
26, and the pulleys 27 making the radial vane 23 located on the drive disk 
22 rotate within 0-80 range. 
According to the above arrangement, the movable radial vane 23 in the 
bellow 100 serves as a swirl generator and the bluff body 29 of the 
central shaft 24 is a fuel injecting device of a general burner. The fluid 
can go through the upper portion 234 of the radial vanes 23 and radially 
enter the radial vanes to coil around the bluff body 29 and go into the 
combustion chamber through the central hole of the biasing block 40. 
Please refer to FIG. 7 which shows a linear relationship between the swirl 
number of the improved radial vane of this invention and the rotary angle 
thereof. By means of the correction of an LDV experimental equipment, a 
good linear relationship between the rotary angle and the swirl number can 
be achieved, and the swirl intensity required by general industrial burner 
can be reached. 
In FIG. 7, the X coordinate is the swirl number, and the Y coordinate is 
the rotary angle. We can see that when the rotary angle increases, the 
swirl number increases in proportion thereto. According to the data, when 
the swirl number increases to a certain value (about 0.6), if the pressure 
gradient in two opposite directions of the injected flow is sufficient to 
overcome the kinetic energy of the axial fluid, a central circulation zone 
can be produced. The circulation zone is a swirl zone which can stabilize 
the burning flame and increase delay time to increase combustion 
efficiency. 
The radial vanes of this invention can eliminate the drawback existing in 
conventional flow-guiding vanes that the fluid passes through the vanes to 
force the vanes to rotate and cause mechanical loss and produce a great 
amount of pressure drop or great amount of pressure drop or high turbulent 
flow effect. Moreover, when the fluid rotates through the bluff body and 
enter the combustion chamber, larger radial momentum is created to reduce 
the energy loss caused by viscosity effect and enhance the capacity of the 
burner.