U.S. patent number 3,890,835 [Application Number 05/269,746] was granted by the patent office on 1975-06-24 for chemical recording of flow patterns.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Richard Dotzer, Winfried Plundrich.
United States Patent |
3,890,835 |
Dotzer , et al. |
June 24, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Chemical recording of flow patterns
Abstract
The flow pattern of a fluid over a surface can be determined by
treating the surface to form a reactive layer, entraining in the
fluid a reagent compound which is capable of chemically changing
the reactive layer, and then passing the fluid over the reactive
layer which is to be examined. This method is illustrated by
treating an aluminum surface of a blade member (such as that in a
vacuum cleaner blower) or adjacent structural members to form a
thin aluminum oxide film by anodic treatment. The microporous film
which is formed is then impregnated with an organic dye. An air
stream containing a reactive substance, such as acid vapors, is
passed over the treated blade member. The acid vapors react with
the dye and/or the oxide layer and produce a visible pattern upon
the blade which is characteristic of the boundary layer flow of the
air stream. An examination of the visible pattern is of assistance
in determining the proper design and operating characteristics of
the blade. The visible pattern may be formed or preserved by
chemical post-treatment, such as etching to leach out dye from
unreacted portions of the layer and to provide a more permanent
record for subsequent use. Alternatively, the microporous aluminum
oxide layer can be treated with a fluid stream containing a
reactive substance to characteristically change the layer, followed
by treatment with a dye to form the visible pattern of the boundary
flow.
Inventors: |
Dotzer; Richard (Nurnberg,
DT), Plundrich; Winfried (Nurnberg, DT) |
Assignee: |
Siemens Aktiengesellschaft
(Munich, DT)
|
Family
ID: |
5812960 |
Appl.
No.: |
05/269,746 |
Filed: |
July 7, 1972 |
Foreign Application Priority Data
Current U.S.
Class: |
73/147;
346/135.1; 430/434 |
Current CPC
Class: |
C25D
11/24 (20130101) |
Current International
Class: |
C25D
11/18 (20060101); C25D 11/24 (20060101); G01m
009/00 () |
Field of
Search: |
;73/147,168 ;346/1,135
;23/253TP |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Swisher; S. Clement
Attorney, Agent or Firm: Kenyon & Kenyon Reilly Carr
& Chapin
Claims
What is claimed is:
1. A method of chemically recording the flow pattern of a fluid
over a surface which comprises:
treating said surface to produce an oxidized layer of aluminum upon
said surface,
passing over said layer a fluid containing a reagent compound which
produces a chemical change upon contact with said layer which is
characteristic of the flow pattern of the fluid over the layer,
and
visibly recording said flow pattern with a dye substance in said
layer.
2. The method of claim 1 wherein said dye is impregnated into said
aluminum oxide layer prior to passing said fluid over said
layer.
3. The method of claim 1 wherein said dye is impregnated into said
aluminum oxide layer subsequent to passing said fluid over said
layer.
4. The method of claim 1 wherein said reagent is a compound which
reacts with said dye to change its color.
5. The method of claim 1 wherein said reagent is a compound which
reacts with said aluminum oxide layer.
6. The method of claim 1 wherein the chemical change in said layer
is further revealed by contacting said layer with an etching
fluid.
7. The method of claim 1 wherein at least two distinguishable dyes
are impregnated into said aluminum oxide.
8. The method of claim 1 wherein said treating comprises applying
to said surface a self-supporting aluminum foil having on one
surface an adhesive and on the opposite surface an aluminum oxide
coating.
9. The method of claim 1 wherein said treating comprises
electro-depositing aluminum upon said surface and treating said
aluminum to form an aluminum oxide layer.
10. The method of recording the flow pattern of a gas over a
surface, which comprises
treating said surface to form thereon an eloxal layer containing
therein an exposed dyeable substance, and
passing over said layer a gas containing a reagent which imparts a
visible change to said dyeable substance.
11. The method of recording the flow pattern of a gas over a
surface, which comprises,
treating said surface to form thereon an eloxal layer which is
microporous,
passing over said layer a gas containing a reagent which reacts
with and seals portions of said layer, and
contacting said layer with a dye to impregnate unsealed portions of
said layer.
12. The method of recording the flow pattern of a gas over a
surface, which comprises,
treating said surface to form thereon a microporous eloxal layer
containing therein an exposed dyeable substance,
passing over said layer a gas containing a reagent which reacts
with at least said eloxal layer to seal portions of said layer,
and
treating said layer to at least remove said dyeable substance from
the portions of said eloxal layer which are not sealed.
Description
BACKGROUND
This invention is directed to the art of determining and recording
the flow characteristics of a fluid past a surface. For example, in
blowers (such as vacuum cleaners) it is desirable to provide
devices with a minimum power consumption, a maximum suction or
output capacity, and a minimum noise level. The power consumption,
suction capacity and noise level of a blower are closely
interrelated and depend directly on each other; more power produces
more suction capacity, and higher suction capacity leads in most
cases to an increase in the noise level. In the last analysis the
objective of design efforts is an optimization of the blower
characteristics by modification and compromise between the various
parameters.
In optimizing the blower design, however, exact information is
required regarding the flow conditions in the blower and at the
sources of noise generation. Mathematical solutions are too
difficult and require too much effort. Purely physical efforts
involving the stroboscopic-photographic determination of the
trajectories of light particles of plastic sprinkled into the air
stream have not been successful.
Therefore a need exists for a technique to analyze the flow
conditions, particularly the flow pattern of fluids over surfaces
of rotors, guide vane rings, blades, airfoils and adjacent
structural members and housings for a wide variety of devices, such
as the vacuum cleaner blower referred to above. As far as possible,
such a method should be applicable to the actual surface, and it
should be possible to record the existing flow conditions without
interference and in a reproducible manner.
Accordingly, it is an object of this invention to provide improved
techniques and devices for chemically recording the flow pattern of
a fluid over a surface. This, and additional objects, and the
manner of achieving them, are set forth more fully in the following
detailed specification.
THE INVENTION
This invention is directed to treating a reactive surface with a
fluid containing a reagent which interacts with the reactive
surface; a dye substance added to the reactive surface prior to, or
after contact of the surface with the fluid, provides a visible
record of the flow pattern of the fluid over the surface.
It has been found that the recording of a boundary layer flow by
chemical means is made possible if an anodically oxidized surface
(referred to herein as the formation of an "eloxal" layer) is
exposed (in an unsealed condition) to an air stream mixed with
reactive acid, alkaline or gaseous chemical reagents, and the
eloxal layer which is differentially altered by the gas stream, is
dyed (or stained).
It has also been noted that the eloxal layer and the dye that may
be present undergo characteristic changes which are dependent on
the local concentration of the reagent in the fluid. As the local
concentration of the reagent conforms to the air compression in the
flow profile, the chemical reagent records the flow pattern of the
boundary layer flow very accurately on the eloxal layer, almost
with "molecular" resolution. This process can thus be termed a
method of chemically recording flow patterns of boundary layer
flow. The process is referred to herein as "chemical recording" (or
"chemigraphy"), and the records obtained are called chemigraphs (or
chemical recordings). Very high-contrast chemigraphs can be
obtained in color, or in several colors, they are referred to as
"eloxal-color-layer chemigraphs."
The eloxal layer is illustrative of the type of microporous layer
which is preferred. The microporous layer can be impregnated with a
dye to produce a visible recording of the flow layer upon treatment
with a fluid containing a dye-reactive reagent or a reagent which
seals the pores of the layer followed by leaching of the unsealed
dye. Alternatively an undyed microporous layer can first be treated
with a reagent which reacts with the microporous layer to
selectively seal its pores and then a dye can be used to produce a
visible pattern of the fluid flow. The microporous eloxal layer is
preferred, but other microporous oxides or synthetic layers may be
used.
The method of this invention is particularly suited for the
recording of steady-state flow conditions in blowers. It allows the
recording of existing flow conditions (flow profiles) directly,
unaltered and reproducibly on the portions of the surfaces which
are contacted by the air flow. Thus the air stream records itself
on the adjoining surface portions of the parts of the blower.
The following figures further illustrate the present invention.
FIG. 1 shows the chemical recording of the boundary layer flow of a
radial rotor with straight, centrically or radially, respectively,
arranged blades.
FIG. 2 shows the chemical recordings of a so-called parallel-blade
rotor with blades curved in sickle-fashion.
FIGS. 3, 4 and 5 show chemical eloxal-red-layer recordings, of the
first rotor of the blower, recorded at 30% output of the blower
motor and contrast-etched by means of sodium hydroxide. FIG. 3
shows the base plate and FIG. 4, the cover plate. The concave side
of the curved, sickle-shaped blade is shown in FIG. 5.
FIGS. 6 to 11 show chemical recordings of the boundary layer flow
of different aerodynamic bodies on small eloxal-dye-layer base
plates.
FIG. 12 shows a boundary flow layer of air directed at an angle
against a sheet member.
FIGS. 1 and 2 show in each case the inside surface of the lower
circular disc (base plate) of the first rotor wheel of a two-stage
blower and show clearly the contact edges of the removed blades.
Both rotors were in rotation during the chemical recording in a
clockwise direction, at a speed of rotation of the blower of 12,000
r.p.m.. They were discolored in a manner characteristic of the
flow.
The areas appearing dark in the figures indicate clearly the
pattern of the air flow; the lighter portions of the area are
regions of under-pressure which are hardly touched by the air
stream. From the flow "shadows" of the three central attachment
straps (in the experiment, the two circular discs of the rotor were
held together by six bolted straps in order to make it unnecessary
to cut the blades, which are also chemically recorded), the main
direction of the flow can be seen particularly clearly in FIG. 1. A
comparison of the two chemical recordings discloses clear
fundamental differences in the pattern of the boundary layer
flows.
The method according to this invention is particularly well suited
for making visible the boundary layer flow of moving fluid media,
particularly of air, gases and vapors of high flow velocity, such
as they appear in parts of blowers. It is used to advantage for the
recording of flow profiles in the rotors, stators and housings of
vacuum cleaner blowers, rotary flow dust separators, counter-jet
pulverizers and cyclone separators. The method designated herein as
"chemigraphic recording of boundary layer flow" provides very
durable, high-contrast flow patterns (chemigraphs). With
appropriate pre-treatment of the surfaces it can also be applied to
parts which do not consist of aluminum material. By evaluating the
chemigraphs of the surface portions adjoining the flowing fluid,
informative insights can be obtained into the spatial flow
processes.
Numerous reagents can be readily and uniformly encorporated in a
fluid medium to react with and modify the color of a dye in an
eloxal layer. Strong acids and bases, and reactive gases are
suitable.
Nitric acid vapors can be added as the chemical reagent to the air
stream, and one can record chemically for eight minutes or longer,
if required. The chemographic recording then shows immediately the
contrast reproduced in the image and is very durable. Ozone also
can be added advantageously to the air stream as the chemical
reagent. As almost all aluminum dyes are by oxidation decomposed,
i.e., modified or destroyed and thereby bleached, full-range
chemical recordings can be obtained in a few minutes with an
oxone-containing air stream. With somewhat higher ozone
concentrations, fractions of a minute are sufficient. For example,
the chemical recording of a red eloxal layer with an acid produces
a stronger color hue in the area of contact whereas the
ozone-containing air stream records the flow patterns as lighter to
colorless areas on the dyed eloxal layer background. The
reproducibility of these chemical recordings is very good, as the
amount of ozone can be fixed and apportioned exactly by means of
the accurately adjustable control parameters of conventional ozone
generators.
It has also been found advantageous in some cases, to use an
eloxadized, unsealed and undyed surface of a blower component. This
technique is useful because not only can the aluminum dye be
altered, but the eloxal layer can also be specifically influenced
by the chemical reagent. In carrying out this method, a surface can
be chemically recorded for several minutes with a fluid containing
nitric acid vapors (or with hydrogen chloride mist). Then, if
desired, the parts can be left at room temperature for several
hours, i.e., about 8 hours for a setting of the chemically recorded
layer, and subsequently placed in a dye bath for about 10 minutes.
After rinsing with water, the chemical recordings are finished. The
portions not contacted by the air stream, which therefore have not
been chemically recorded, will have absorbed dye and thereby are
clearly distinguished from the colorless chemically recorded
boundary layer flow areas.
Thus, the reagent in the fluid can be of different functional
types, one which reacts with the dye in the eloxal layer to change
the color of the dye, or which reacts with the eloxal layer to seal
its ports, or a combination of such reactions. The choice of
reagent can be readily made from those known to react with dyes
and/or to seal microporous structures such as an eloxal layer.
A further, particularly advantageous embodiment is to chemically
post-treat the eloxal layer which is differentially altered by the
method of this invention. In the case of chemical eloxal-dye-layer
recording, this process is called "contrast etching". A reduction
of the exposure time is thereby achieved (to 3 to 5 minutes) and a
chemigraph of even higher contrast is obtained, as is shown in
FIGS. 3 to 5.
The flow profiles on the base plate (FIG. 3) as well as those on
the inside of the cover plate (FIG. 4) can be seen most clearly.
Even before the chemigraphic reaction between the chemical reagent
and the eloxal-dye layer becomes optically visible as a color
differentiation, the chemical reagent has changed the structure of
the eloxal layer and the dye so that the chemically recorded
portions of the surface show a considerably more resistant behavior
than the areas which have been exposed less or not at all.
For contrast etching, practically any aluminum dyes can be used,
although the strongly dyed basic colors red, yellow and blue (and
as a mixed color, green) are preferred because they provide sharp
contours and clear contrast.
The chemical post-treatment can be a brief etching, which can be
performed with acids as well as with alkaline solutions. The more
easily and rapidly the dye can be locally dissolved, the less the
eloxal dye layer has been exposed in the chemical recording, i.e.,
the less its state has been changed. Immersion times of between 5
and 30 seconds are sufficient for the etching process; with
immersion times of over five minutes fuller decomposition of the
chemigraphic image will occur. If sodium hydroxide is used,
immersion times of less than 5 seconds are sufficient. For 20%
sodium hydroxide, for instance, an immersion time of three seconds
has been found suitable. Immediately after the etching operation
the surface is rinsed liberally with water and finally dried
between filter paper.
Other etching media which have been found are concentrated aqueous
ammonia and particularly, nitric acid and sulfuric acid with the
immersion times mentioned above. It has been found advantageous to
chemically record and contrast-etch with the same acid. The
chemical recording is perferably done with nitric acid vapor, and
this acid is then used for the contrast etching. A concentration of
about 65% acid produces clear contrast between the chemically
recorded eloxal-dye-layer areas and the colorless parts of the
surface which have not been exposed.
While alkaline solutions attack the eloxal layer structure for
chemical reasons, this is not directly the case with the acid
etching media. However, they dissolve the aluminum dye very rapidly
from the chemically recorded aloxal-dye-layer areas and apparently
do not alter the structure of the eloxal layer. Thus, the eloxal
layer areas relieved of dye in the contrast etching can be dyed
again. It is advantageous to use an aluminum dye which contrasts
with the dye first used, as for instance:
1st dyeing operation 2nd dyeing operation
______________________________________ red blue yellow blue red
black yellow black blue yellow
______________________________________
The chemically recorded eloxal-dye-layer areas of the first dyeing
operation are not altered in the second dyeing operation. Only in
the partially chemically recorded border zones of the flow are they
dyed proportionally. This color contrasting in chemical recording
constitutes a further refinement. It can furnish additional
information regarding the flow pattern in the border zones.
The etching technique is also useful where the reagent in the fluid
does not visibly change the color of the dye. Thus the reagent may
only serve to seal the microporous structure of a dyed eloxal layer
at characteristic areas of the boundary flow layer. Upon etching of
leaching the dye is removed from the unsealed areas to provide a
visible pattern.
The dyeing of the aluminium layer can preferably by carried out
with two or more aluminium dyes. The contrast of the chemical
recording is thereby enhanced.
Almost hte entire spectrum of the so-called aluminium dyes (or
stains) offered commercially for the dyeing of eloxal layers can be
used for the chemigraphic recording of boundary layer flow, for
example Alizarin-, Indigo-, Azo-, Cotton-, Metal-Complex-dyestuffs
according to B. S. WERNICK and R. PINNER handbook "The Surface
Treatment and Finishing of Aluminium and its Alloys" third edition,
in German "Die Oberflachenbehandlung von Aluminium" page
367-369.
The microscopic depressions existing in the eloxal layer are first
filled partially with the one dye, and then partially with the
other dyes. They may, for instance, first be filled with a blue dye
and then on top with a yellow dye. The resulting color effect is
green. In chemical recording, the yellow dye is partially altered
or decomposed, respectively, and at other points, all dyes are
affected, depending on the concentration of the chemical reagent
caused by the flow. Thus a flow pattern differentiated by
green-blue-colorless is obtained.
The chemical recording sensitivity of the eloxal dye layer can be
reduced by partial sealing of the microscopic depressions. To lock
the dye in the eloxal layer, the surface can be sealed in boiling
water for 30 minutes to 1 hour.
Eloxal-red-layer chemigraphs have been found to be excellent on the
basis of their color contrast, which can be obtained by dyeing the
eloxal layer with a red dye, and sealing and exposing with nitric
acid-containing vapors.
Suitable red dyes are, for instance, the following:
Aluminium -- True red B 3 LW Aluminium -- dark red LW Aluminium --
ruby B LLW Aluminium -- red RLW Aluminium -- red GLW Aluminium --
true gold Aluminium -- blue LLW Aluminium -- green GLW Aluminium --
true bronze L Aluminium -- copper 2 RLW Aluminium -- orange GL
Aluminium -- gold yellow GLW Aluminium -- true blue G Aluminium --
purple BLLW Aluminium -- turquoise PLW Aluminium -- red brown
RLLW
With the chemigraphic reagent ozone, indigo and its derivates are
particularly well suited as are Redox indicator dyes such as, for
instance, methylene blue, Congo red, toluylene blue, thiazine,
safranin T, and neutral red. Furthermore, dyes which change by
oxidation in air have been proven highly suitable. Steam vapors can
also be used as the chemical reagent to react with the dyeable
substance or eloxal layer.
The reagent compound, in vaporous or gaseous form, is readily
dispersed in and mixed with the fluid stream by conventional means.
The fluid stream may be passed over a vat of rising vapors or a gas
generator can direct reagent gases or vapor into the fluid stream.
A baffle network or mixing device may be used if desired to ensure
even dispersion of the reagent in the fluid stream.
The eloxal layers prepared by customary methods through anodic
oxidation of the surface are suitable for carrying out the method
of this invention. The well-known d-c sulfuric acid method (GS
method) is the most widely employed and most inexpensive process
for the anodic oxidation of aluminum and aluminum alloys. The
eloxal layers produced thereby have a microporous or honeycomb-like
fine structure. These non-conducting, mechanically strong surfaces
are particularly resistant against atmospheric influences and
accept dye very well. When dyeing with commercially available
aluminum dyes, for instance, those marketed by the firm Sandoz, AG,
Basle, Switzerland, the dye molecules (mostly organic azo dyes) are
impregnated into the microscopic depressions of the eloxal layer,
which are about 100A in diameter and about 10 .mu.m depth. The dye
is therefore not on the surface but in the eloxal layer and is not
carried away by gas even of very high flow velocities. At the same
time the eloxal surface presents a very homogenous and, if
required, even polishable surface, which does not interfere with
the flowing media. It is also thermally stable.
Alternative methods of forming an eloxal-type coating can also be
used. For example commercial coating are also made by treating the
aluminum in an electrolyte of chromic acid, oxalic acid, or oxalic
acid mixed with sulfuric acid. Artificial oxide coatings can be
formed in aluminum articles by chemical treatment as well as by
electrochemical treatment. These chemical coating are not as thick
or as hard nor as abrasion-resistant as anodic coatings, but for
many purposes they are adequate.
The chemigraphic recordings can be made of practically unlimited
durability by "sealing" after the chemigraphic exposure. This can
be accomplished,, for instance, by sealing for 30 minutes in
boiling water or in a commercially available sealing salt bath.
The original chemigraphs obtained by the method of this invention
can be preserved by means of photography in color or in black and
white. For comparison purposes the photographs can also be
evaluated quantitatively by means of photometry. The chemigraphs
can also be used as standards of proper flow patterns for purposes
of matching new blade or structural units with a known standard of
a flow pattern that has proven to be effective.
The eloxal layer may consist of an anodically oxidized surface of
an aluminum part. A particularly advantageous embodiment of the
method according to the invention is based on the use of a
self-adhering eloxadized aluminum foil. In many cases it may be
found to be particularly advantageous to dye the eloxal layer.
If the part to be tested is not made of aluminum, or does not have
an aluminum surface, an aluminum foil or sheet coated with an
eloxal dye layer can be cemented on to the surface of the part or
equipment for carrying out the method of this invention. A test
piece can also be aluminum-plated by electro-deposition and
subsequently eloxadized. Rotors or blowers of brass or sheet steel
can, for instance, be aluminum-plated by electroplating, eloxadized
and then dyed and chemically recorded on by the method of this
invention.
By using an eloxadized aluminum foil, the method according to this
invention becomes practically independent of the kind of material
of the part or equipment which is to be tested for its aerodynamic
characteristics. In principle, any kind of aluminum foil is
suitable, which is eloxal-coated on one or both sides, and is
undyed or dyed with a suitable aluminum dye. The foils are cemented
to the surface portions of the part or equipment which is of
interest from a flow point of view, and the boundary layer flow
profiles are recorded by the method according to this invention.
The impregnated paper-laminated, self-adhering aluminum foil, which
is commercially available in sheet form or as yard goods, is
particularly well suited for carrying out the method described
herein. The foil is cut to conform to the surface portions to be
tested by chemical recording and affixed to the surface of the
object with its adhesive side. After the chemical recording, the
self-adhering foil, which has the flow profiles recorded in the
dyed eloxal layer, can be stripped off the surface. The foil can be
preserved for purposes or comparison or documentation, and can be
mounted on a rigid support, such as cardboard, for ease of
handling.
Particular advantages of this embodiment are seen, for instance, in
the fact that the self-adhering eloxal-dye-layer aluminum foil is
applicable regardless of the base material of the part or equipment
to be chemically recorded. The use of such foil furthermore makes
the method independent of anodizing and dyeing equipment, and it
can be used at any location. The boundary layer flow at given
portions of the surface of parts or equipment can be chemically
recorded with different foil pieces as many times as desired under
different flow conditions and can be compared very well visually by
juxtaposition of the chemical recordings on the foil pieces and
evaluated with respect to changes that may have occured.
In particular, the self-adhering eloxal-dye-layer aluminum foils
can be cemented on non-planar, convex- or concave-cylindrical
surfaces or differently shaped surface portions, and the chemically
recorded parts of the foils can be cemented side-by-side on flat
cardboard for comparison purposes. The foil also offers the
possibility to investigate, on the basis of different aluminum dyes
and chemical recording reagents, the surface areas of interest
under the same flow conditions by means of chemical recording
methods which record with different speed and resolution, and so to
obtain more information regarding the flow process. For example an
eloxal layer can be formed with an acid-reactive dye and
basic-reactive dye(or more generally, two or more dyes which are
subject to distinguishable visible changes at different pHs). A
first flow condition can then be established with a fluid
containing an acid entrained therein and subsequently a second flow
condition (i.e. a faster rate) can be established with the fluid
containing a base entrained therein. This leads to a single eloxal
layer containing two distinguishable patterns which reflect the
changes in boundary layer flow caused by the different flow
conditions.
In order to protect the exposed (unsealed) and therefore
dirt-sensitive eloxal-dye layers against contamination and
modifying influences, it may be advisable to cover them with a
removable protective foil. This is recommended particularly if the
self-adhering eloxal-dye-layer foil is to be stored for an extended
period of time. In the case of sheets and yard goods, the insertion
of an inert sheet, for instance, a commercially available thin
polyethylene foil, is sufficient for this purpose.
The invention will be explained more fully by the following
examples:
EXAMPLE 1
A 1-mm thick sheet of "Raffinal" (a high-purity aluminum sheet),
which had eloxadized to a thickness of about 10 .mu.m by the GS
method, was dyed for 10 minnutes at room temperature in a dye bath
with an Azo-dyestuff like A1 True Red B3LW (made by Sandoz) at a
concentration of 5 g/liter. From a nozzle of 2 mm diameter (placed
onn the left side) the eloxal-dye layer was exposed to an air
stream of 500 liter/h at an angle of inclination of 5.degree.C. The
air stream contained at the chemical reagent the vapors carried
along by it from the gas space above 65-% nitric acid at room
temperature. The chemical recording time was 75 seconds
(approximately 50 mg of HNO.sub.3). The boundary layer flow pattern
shown in FIG. 12 was obtained, which shows the heavily exposed
inner cone and the wide outer cone, which is differentiated by its
color. Although the chemigraph was not sealed, it was very
durable
EXAMPLE 2
According to the description in Example 1, an eloxal-red-layer
chemigraph was prepared, pursuant to the following
specifications.
Object: P-wheel of the VS 26 vacuum cleaner blower
Material: Sheet of aluminium alloy
Pre-treatment: Degreased in TRINORM A1: GS eloxation for for 30
min;
Dyeing: in a dye bath with 5 g/liter of an Azo-dyestuff like A1
True Red B3LW(made by Sandoz); 10 minutes at room temp.;
Chemical reagent: 65 % HNO.sub.3 vapors at room temperature
(approx. 20 mg of HNO.sub.3.min);
Exposure time: 8 minutes at a suction rate of 32 liter/sec of
air.
The eloxal-red-layer chemigraph obtained corresponds to that of
FIGS. 1 and 2.
If the chemical recording exposure is only 3 to 5 minutes, a
high-contrast chemigraph can also be obtained by a 3-min heat
treatment at 100.degree.C in a drying cabinet, and also by contrast
etching, as described above.
EXAMPLE 3
According to the description in Example 1 and using the object,
material and pre-treatment of Example 1, an eloxal-blue-layer
chemigraph was prepared pursuant to the following
specifications.
Dyeing: 3,5 g/liter of an Indigo-dyestuff like A1 Blue LLW; 10
minutes at room temperature
Chemical reagent: Ozone, approximately 30 ml of O.sub.3 gas to 1920
liter of air per minute;
Exposure time: 1 minute at a suction rate of 32 liter/sec of
air;
Result: Immediate chemigraph with blue-colorless contrast.
EXAMPLE 4
According to the description in Example 1 and using the object and
material, and according to the pre-treatment, of Example 1, an
eloxal-yellow-layer chemigraph was prepared and contrast-etched
under the following conditions:
Dyeing: 10 g/liter of an Alizarin-dyestuff like A1 Yellow; 5
minutes at room temperature;
Chemical reagent: Nitric acid vapors of 65-% NHO.sub.3 at room
temperature; approximately 20 mg of HNO.sub.3 per minute;
Exposure time: 5 minutes at a suction rate of 18.5 liter/sec of
air;
Etching medium: 65-% NHO.sub.3 ;
Etching time: 5 sec, then liberal rinsing with water;
Result: Immediate chemigraph with yellow-colorless contrast.
EXAMPLE 5
Similarly as in Example 4, an eloxal-green-layer chemigraph with
color contrast was prepared, using the following:
Dyeing: 3.5 g/liter of an Indigo-dyestuff like A1 Blue LLW, 2.5 min
at room temp.,
Chemical reagent: Nitric acid vapors of 65-% HNO.sub.3 at room
temperature, approximately 20 mg of HNO.sub.3 per min;
Exposure time: 5 minutes at a suction rate of 18.5 liter/sec of
air;
Etching medium: 65-% HNO.sub.3 ;
Etching time: 10 sec, then liberal rinsing with water;
Dyeing: 10 g/liter of A1 Black MLW; 5 min at room temperature;
Result: Chemigraph with strong green-black contrast.
EXAMPLE 6
Eloxal-red-layer chemigraphs according to FIGS. 6 to 8 were
obtained using the following:
Object: Aerodynamic body model (drop 1, cylinder 2, cup 3) between
sheet metal surfaces (4, 5, and 6 respectively) in the flow
channel. The aerodynamic bodies of the same cross section (10
.times. 10 mm), exhibit different flow resistance due to their
different shapes, which can be made visible chemigraphically via
the width of the pressure head zone;
Material: Aluminium for the aerodynamic bodies, Raffinal for the
sheet metal pieces;
Pre-treatment: TRINORM A1 degreasing; chemical burnishing; GS-
eloxation for 30 minutes;
Dyeing: in a dye bath with 5 g/liter of an Azo-dyestuff like A1
True Red B3LW (made by Sandoz); 7 minutes at room temperature;
Chemical reagent: Nitric-acid vapors from 65-% HNO.sub.3,
approximately 50 mg/min;
Exposure time: 2 min at a suction rate of 7 liter/sec of air;
Result: Chemigraphs of the boundary layer flow on the surfaces of
the aerodynamic bodies and on the adjoining surfaces of the sheet
metal surfaces were obtained.
EXAMPLE 7
Eloxal-red-layer chemigraph according to FIGS. 9 to 11 were
obtained with material, pre-treatment, dyeing, chemical reagent and
exposure time as in Example 6. The objects were a wing profile 7,
triangular wedge 8 and an asymmetrical angle piece 9 as model forms
between sheet metal surfaces (10, 11 and 12, respectively) in a
flow channel.
Chemigraphs of boundary layer flow with dark-red contrast were
obtained on the model forms and sheet-metal surfaces, which
correspond to the aerodynamic expectations.
EXAMPLE 8
An eloxal-red-layer chemigraph with contrast etching was prepared
by using the following.
Object: P-wheels of the VS 26 blower;
Material: Sheet steel and brass, respectively;
Pre-treatment: Aluminium-plated by electrodeposition (approx. 25
.mu.m of A1) and eloxadized (eloxal layer about 8 .mu.m thick);
Dyeing: in a dye bath with 5 g/liter of an Azo-dyestuff like A1
True Red B3LW; (made by Sandoz) 8 minutes at room temperature;
Chemical reagent: Nitric acid vapors from 65-% HNO.sub.3 ;
approximately 20 mg of HNO.sub.3 per min;
Exposure time: 3 minutes at a suction rate of 32 liter/sec of
air;
Etching medium: 65-% HNO.sub.3 ;
Etching time: 10 sec, then liberally rinsing with water.
A chemigraph with red-colorless contrast was obtained as with the
P-wheels made entirely of aluminium, i.e., the eloxadized and dyed
electro-deposited aluminium corresponds fully to a equivalent
eloxal-dye layer and accordingly produces fully equivalent
chemigraphs.
EXAMPLE 9
A chemigraph with colorless-blue contrast was prepared as
follows:
Object: P-wheel of the VS-26 vacuum cleaner blower;
Material: Sheet of aluminium alloy;
Pre-treatment: Degreasing in TRINORM A1, eloxa dizing form 30
min;
Chemical reagent: Nitric acid vapors from 65-% HNO.sub.3 at room
temperature, approximately 20 mg HNO.sub.3 /min;
Exposure time: 5 minutes at a suction rate of 32 liter/sec of
air;
Settling time: About 8 hours at room temperature;
Dyeing: 8 g/liter of an Indigo-dyestuff like Blue LLW; 10 minutes
at room temperature;
Result: Colorless-blue chemigraph with sharp contours.
EXAMPLE 10
Similarly as in the descriptions in the preceding examples, a
vacuum cleaner blower was eloxadized and chemical recordings made.
The vacuum cleaner blower is a two-stage blower. Two rotor wheels,
which are mounted in tandem on a shaft and are separated from each
other by a stationary guide vane wheel, are driven by an electric
motor. The air entering the first rotor wheel centrally is
accelerated radially outward, is deflected at the housing and is
fed through the guide vane wheel inward to the second rotor wheel,
which accelerates the air again radially outward. The two rotor
wheels have the same shape and each consist of two circular discs
which are rigidly connected by six curved, sickle-shaped, radially
and symmetrically arranged webs, the so-called rotor blades. With a
circular disc diameter of 130 mm, the rotor blades are 8 mm high
and are riveted by means of suitable tabs firmly to the circular
discs. The guide vane wheel which, with a diameter of 150 mm, is
somewhat larger, looks similar, and consists likewise of two
circular discs perforated in the center, which are firmly connected
with each other by eight, 8 mm high guide vanes in a similar
manner. The guide vanes are straight webs, symmetrical, but are not
arranged centrically about the center. The rotor wheels are fixed
on the shaft of the electric motor by means of a balancing nut and
can reach up to 20,000 r.p.m. The parts of the blower and the
electric motor are enclosed by a housing with a cover and they
constitute the vacuum cleaner blower.
The rotor wheel and the guide vane wheel are made of aluminum. The
chemigraphs obtained give information regarding the parts of the
blower, the influence of the shape of the blades, the inner and
outer attack angle of the blades, the shape of the entrance
openings and, in the last analysis, information regarding the flow
distribution and noise generation in the flow spaces between the
blade and disc surfaces. They make it therefore possible to
optimize the blower parameters and to improve the blower efficiency
without increasing the noise level.
EXAMPLE 11
A sheet, 500 .times. 700 mm, of aluminum foil from JACKSTAEDT and
Company, Wuppertal-E, with about 50.mu.m of aluminum, with shiny
aluminum surface (WI-CA 1 52125) or matte (WI-52124) and laminated
on one side with adhesive and removable impregnated paper, is freed
of the thin protective lacquer film applied for manufacturing
reasons by means of dischloromethane. In order to remove the last
lacquer residue, the laminated aluminum foil is briefly immersed in
diluted sodium hydroxide (10 to 20 %) and subsequently thoroughly
rinsed in water. Any degreasing that may be necessary is done by
immersion for 10 to 20 seconds in TRINORM A1 (Schering).
The aluminum foil, which is laminated on one side, is then
anodically oxidized in the well-known d-c sulfuric-acid GS
eloxadizing bath at 18.degree.C for 30 minutes with a current
density of 1.5 A/dm.sup.2 at a voltage of 16 V, and an eloxal layer
of 10 to 12 .mu.m thickness is produced. subsequently the aluminum
foil, now coated with an eloxal layer, is washed thoroughly for 5
to 10 minutes in water and dyed red for 10 minutes at room
temperature in a dye bath with an Azo-dystuff like Aluminum True
Red B3LW (SANDOZ AG, Basel) at a dye concentration of 5 g/liter.
After a brief rinse in distilled water, the eloxal-red-layer
aluminum foil is wiped off with filter paper and is allowed to dry
at room temperature in clean air. The unsealed, self-adhering
aloxal-red-layer aluminum foil is now ready for the chemical
recording of boundary layer flow.
The inner wall of a glass tube of 30 cm length and 10 cm side
diameter is coated with the self-adhering eloxal-red-layer aluminum
foil, after the calculated area was first cut out from the 500
.times. 700 mm sheet and the impregnated paper foil stripped off.
In order not to contaminate the eloxal-red-layer in handling, it is
recommended to use clean protective gloves. The boundary layer flow
within the tube was determined from an air jet with a discharge
orifice of 2 mm in diameter, inclined 45.degree. from the axis of
the tube. An air stream from the jet, at a 500 liter/hr nominal
flow rate, was mixed with nitric acid vapors which were carried
along from the gas space over 65% HNO.sub.3, (approximately 50 mg
of HNO.sub.3 were fed into the air stream per minute). An exposure
time of 75 seconds (duration of the blast of air containing
HNO.sub.3 vapors), was used to produce the corresponding boundary
layer flow profile on the eloxal-red-layer aluminum foil within the
tube.
The flow profile can be made permanently and clearly visible by
removing it from the wall of the glass tube, covering the adhesive
with the impregnated-paper foil, and contrast etching the
chemigraphic image. The finally sealed chemigraphic picture can
then be mounted and is permanently available for evaluation and
comparison.
The inside wall of the glass can be covered again with a
self-adhering eloxal-red-layer aluminum foil made under the same
conditions and chemigraphs can be recorded under different flow
conditions.
This invention has been described in terms of specific embodiments
set forth in detail. Alternative embodiments will be apparent to
those skilled in the art in view of this disclosure, and
accordingly such modifications are to be contemplated within the
spirit of the invention as disclosed and claimed herein.
* * * * *