U.S. patent number RE31,258 [Application Number 05/952,695] was granted by the patent office on 1983-05-31 for fluid velocity equalizing apparatus.
This patent grant is currently assigned to Air Monitor Corporation. Invention is credited to Kenneth W. De Baun.
United States Patent |
RE31,258 |
De Baun |
May 31, 1983 |
Fluid velocity equalizing apparatus
Abstract
Apparatus for equalizing the velocity of fluids flowing in duct
work and the like which comprises one or more rigid honeycomb
sections having a plurality of coaxial passages wherein the ratio
of the surface area of each passage to its cross-sectional area is
in the order of thirty or greater .Iadd.and the length of the
individual passages is varied to provide longer passages in the
center of the duct than along the sidewalls of the
duct..Iaddend.
Inventors: |
De Baun; Kenneth W. (Santa
Rosa, CA) |
Assignee: |
Air Monitor Corporation (Santa
Rosa, CA)
|
Family
ID: |
27061591 |
Appl.
No.: |
05/952,695 |
Filed: |
October 19, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
524740 |
Nov 18, 1974 |
03964519 |
Jun 22, 1976 |
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Current U.S.
Class: |
138/37;
138/41 |
Current CPC
Class: |
F15D
1/02 (20130101) |
Current International
Class: |
F15D
1/02 (20060101); F15D 1/00 (20060101); F15D
001/02 () |
Field of
Search: |
;138/37,39,41,44
;73/168 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Footland; Lenard A.
Attorney, Agent or Firm: Anderson; Ernest M.
Claims
I claim: .[.1. Apparatus for equalizing the velocity of flowing
fluid including duct means defining a flowing stream of fluid; at
least one open-ended honeycomb equalizing section substantially
coaxial with said duct means, intercepting and conducting the fluid
therethrough, said honeycomb section having a plurality of parallel
passages across substantially the entire duct cross-section wherein
the ratio of surface area of each passage to the cross-sectional
area of each passage is at least 30..]. .[.2. The apparatus of
claim 1 wherein the end of the honeycomb facing the stream of fluid
is curved to flatten the velocity profile of the stream..]. .[.3.
The apparatus of claim 1 further comprising an air straightening
honeycomb section preceding the first-mentioned honeycomb
section..]. .[.4. The apparatus of claim 3 wherein the ratio of the
surface area of each passage of said straightening honeycomb
section to its cross-sectional area is in the order of 6..]. .[.5.
The apparatus of claim 1 wherein the parallel passages are
approximately 3 inches in length or greater..]. .[.6. The apparatus
of claim 1 wherein the parallel passages are of hexagonal
cross-section having dimensions of 3/8 to 3/16 inch across
flats..]. .[.7. The apparatus of claim 1 wherein the lengths of
said parallel passages vary over the cross-sectional area of said
conduit to equalize the fluid flow velocities across the
cross-sectional area of said conduit..]. .[.8. Apparatus for
equalizing the velocity of flowing fluid including duct means
defining a flowing stream of fluid; at least one open-ended
honeycomb equalizing section substantially coaxial with said duct
means, intercepting and conducting the fluid therethrough, said
honeycomb section having a plurality of passages across
substantially the entire duct cross-section, said parallel passages
having hexagonal cross-sections, each passage being approximately 3
inches in length or greater and having a dimension of 3/8 to 3/16
inch across flats..]..Iadd. 9. Apparatus for equalizing the
velocity of flowing fluid including duct means defining a flowing
stream of fluid; at least one open-ended honeycomb equalizing
section substantially coaxial with said duct means, intercepting
and conducting the fluid therethrough, said honeycomb section
having a plurality of parallel passages across substantially the
entire duct cross-section wherein the ratio of surface area of each
passage to the cross-sectional area of each passage is at least 30
and the end of the honeycomb facing the stream of fluid is curved
to flatten the velocity profile of the stream. .Iaddend..Iadd. 10.
The apparatus of claim 9 wherein the lengths of said parallel
passages vary over the cross-sectional area of said conduit to
equalize the fluid flow velocities across the cross-sectional area
of said conduit. .Iaddend.
Description
This invention relates generally to apparatus for conditioning the
flow pattern fluids flowing in conduits and it more particularly
refers to apparatus for equalizing the velocity profile of fluid
flowing in a conduit. This invention is an improvement upon air
conditioning apparatus of the type disclosed in U.S. Pat. No.
3,733,900 issued to Kenneth W. De Baun on May 22, 1973 and is
useful in the type of apparatus disclosed in U.S. Pat. No.
3,842,678 issued to Kenneth W. De Baun and Robert W. Noll on Oct.
22, 1974.
The principal object of this invention is to modify the flow
pattern of fluids flowing in enclosed conduits.
One object of the invention is to shape the velocity profile of air
flowing in duct work used for air conditioning so that accurate air
flow measurements can be made.
Other objects and advantages of the invention will become apparent
from consideration of the following description of a specific
embodiment and the accompanying drawings wherein
The accompanying drawing is a schematic sectional elevational view
of the apparatus with its components installed at the discharge of
an air blower or fan.
The drawing illustrates schematically a fan or blower 1 delivering
air through a conduit or duct 2 to an air conditioning or other
system at its far end 7. The described system includes a curved
equalizing honeycomb section 7, a straight equalizing honeycomb
section 5, and a straightening honeycomb section 6.
Air being discharged from a blower or fan 1 typically has turbulent
and stratified flow conditions at the discharge zone 11 as it
enters typical air conditioning ductwork. The air may have greater
velocity on one side of the duct such as at 31b and may have a
variety of flow patterns such as the multi-directional turbulence
shown at 31a. There also may be stratification with more air
flowing at 31b than at 31a per unit cross-sectional area of the
duct.
In order to measure the quantity of air flowing through the duct or
to sample its constituents by instrumentation placed, for example,
at 3 such as an air monitoring system of the type disclosed in the
U.S. Pat. No. 3,685,355 or the sampling system disclosed in U.S.
Pat. No. 3,842,678, the air flow must have a generally flat profile
as shown at 12. The equalizing honeycomb sections 4 and 5 achieve
the flat profile and the straightening honeycomb section 6 assists
by initially straightening the turbulent pattern 31a, 31b at the
fan discharge. As is more fully described in U.S. Pat. No.
3,733,900, to which reference is made above, the straightening
honeycomb section 6 installed in the duct will straighten the
direction of air flow from the turbulent condition at zone 11 to a
generally coaxial flow condition at 33. However, the flow pattern
still may have an irregular velocity profile with greater velocity
along one side wall at 21 than along the other sidewall at 22, for
example. The passages 32 in the straightening honeycomb section 6
are sized so that the straightening function can be
accomplished.
The honeycomb section 6, and sections 4 and 5, are parallel cell,
expanded honeycomb made of aluminum or other rigid material. The
honeycomb forms a plurality of relatively small, coaxially
extending passages that fill the entire cross-section of the duct
2. The depth, or axial extent of the honecomb is determined by the
relationship of the passage opening area to the passage wall
surface area. The wall thickness of the honeycomb is extremely
small (96% free area) so that there is a negligible loss of air
pressure when air flows through the honeycomb passages. To perform
the straightening function, the ratio of the peripheral area of
each passage to its cross-sectional area should be in the order of
6 for straigtening without undue pressure drop or drag on the
fluid.
However, if the passages in the honeycomb have a substantially
greater peripheral surface area relative to their cross-sectional
area, they perform the velocity equalizing function of the
equalizing honeycomb sections 4 and 5 of the present invention.
Smaller diameter passages produce a drag effect on the fluid as it
passes through them. Resistance to flow varies with the square of
the fluid velocity so that the drag reduces the higher velocity air
flow rates and permits the lower velocities to increase in relation
to them. In this manner the high velocity of air at 21 passing
through the passages 24 of the first equalizing honeycomb section 5
will be suppressed whereas that moving in the region 22 at slower
velocity will not be suppressed as much. Therefore, after passing
through equalizer honeycomb section 5 the air flow assumes the
pattern illustrated at 14, 15 where there is less difference in the
velocity between the air flowing in the center at 14 and that along
the sidewalls at 15. .Iadd.So much is known. .Iaddend.
.[.The.]. .Iadd.It has now been found that the .Iaddend.velocity
profile can be flattened even more by adding a subsequent equalizer
honeycomb section 4. Instead of having straight walls like that of
section 5 it may have an arcuately shaped edge facing the air
stream as shown at 17 and a flat face 16 on the downstream side.
The particular curvature can be adjusted to accommodate any air
velocity profile of the fluid approaching the equalizer honeycomb 4
with, for example as shown in .[.FIG. 1.]. .Iadd.the
drawing.Iaddend., longer passages 13 in the center for the higher
velocity portions of air at 14 and shorter passages along the
sidewall to accommodate the slower portions 15 of the approaching
air stream. In this manner the velocity profile can be
substantially flat like that at 12 when it enters the air
monitoring or sampling instrumentation at 3.
In order to perform an air equalizing function to flatten the
velocity profile of the flowing fluid the passages in the honeycomb
must be substantially smaller in diameter than those for the air
straightening function of a honeycomb such as section 6. In
addition, there is a definite relationship between cross-sectional
area and length. The most efficient air equalizing performances
have been obtained using honeycomb passages wherein the ratio of
the surface area of each passage to its cross-sectional area is in
the order of 30 or greater. Thus, in typical air conditioning
systems, the air straightening honeycomb section can be in the
order of 3 inches long with hexagonally shaped openings 3/4 inch
across the flats. On the other hand, in order to perform the air
equalizing function, the honeycomb passages of sections 4 and 5 in
typical air conditioning systems should be in the order of 3 inches
long and 3/8 inch across the flats of each hexagonal cross-section.
Shaped equalizer honeycomb sections like 4 having lengths of 6 to
10 inches for the honeycomb passages and dimensions of 3/8 to 3/16
inch across the flats of the hexagonal cross-sections have been
found to be useful.
It will be apparent that the descibed velocity equalizing apparatus
is useful in a number of fluid flow applications. Various
modifications of the described system will become apparent to those
skilled in the art without departing from the scope of the
invention defined in the following claims.
* * * * *