Smoke Flow Visualization System Group: 9

Smoke Flow Visualization System Group: 911

Smoke Flow Visualization System Group: 9

2012MEC 204 Basic Thermodynamics Lab Project 12/8/2012

MEC 203Basic Thermodynamics Lab

Name of the ProjectSmoke Flow Visualization SystemGroup:9

Section: DayBSME

Prepared ForInstructorSunjida FerdousDepartment of Mechanical Engineering

IUBATInternational University of Business Agriculture and Technology

Fall-2012

Group Member List

Name ID Mobile Number01. Abdullah Al Amin...12107144..0155703681802. Md.Enamul Hoque Khan12107018..0183470828103. Tayeb Hasan12107102..01843819146

Letter of Transmittal Dec 8, 2012Instructor: Sunjida FerdousBasic Thermodynamics Lab (MEC 204)IUBAT- International University of Business Agriculture and Technology4, Embankment Drive Road, Uttara Model Town,Sector # 10, Dhaka-1230, Bangladesh

Dear Madam,

We have pleasure in submitting the report on Smoke Flow Visualization System. According to your requirement we have prepared this report as far as possible. It is so pleasurable work because; we have gained much knowledge about Smoke Flow Visualization System. Now we can determine how Smoke flow visualization work in wind tunnel .We would like to inform you that we have completed our report fully. We have completed our assignment within convenience time.

We tried our level best to achieve our goal to make a realistic and informative research paper. Now we express our heart full gratitude to you to go through this report and make your valuable comments. Thank you, Madam Yours sincerely

------------------------------------- Group: 9

Acknowledgement:

First of all we would like to thank our almighty Allah for his kindness. Then wed like to thanks our faculty Sunjida Ferdous who gives us such an opportunity to make a report and analysis of Smoke Flow Visualization Systems. I finally would like to thanks to all of my group members who support me and supply the information about the topics. We all our group members work hard to make a good and presentable report on Smoke Flow Visualization Systems. We gathered information from books and internet browsing. Thats way we complete our report and gathered much knowledge about it. Finally we tribute our report to our parents as there prayer or bless for us all the time.

Declaration:

We are three student of BSME (BSc in Mechanical Engineering) in IUBATInternational University of Business Agriculture and Technology prepared a report for our honorable faculty Sunjida Ferdous. This report is related to the project of Smoke Flow Visualization System which made by our senior brothers of 7th semester in this university.We also use different books and different websites to make this report. This report is only for our personal study and analysis. And it has not a single purpose to hit any others mind and thinking.

Table of Contents Title Name Page 1. Background.....09 2. Introduction.10 2.1. Objectives..12 2.2. Methodology..13 3. Application of the smoke flow visualization system..13 4. Smoke wire wind tunnel design..14 5. Photographing techniques18 6. Experimental setup.22 7. Discussion....27 8. Progress forecast....29 9. Recommendations..31 10. Conclusions..32 11. References.33

Project Overview: Background Introduction Objectives Methodology Application of the smoke flow visualization system Smoke wire wind tunnel design Photographing techniques Experimental setup Discussion Progress forecast Recommendations Conclusions References

1. Background

o help understand fluid dynamics, heat transfer, and general aerodynamic principles, scientists and engineers have held a great interest in visualizing airflow. Flow phenomena can be studied and used to verify and even introduce theories. A very practical and useful method to visualize airflow is by the use of smoke flow visualization. Because we are not able to see clean air with free eyes. So we need the help of smoke to understand the movement of the air.There have been many scientists who have experimented with airflow methods and testing. Improvements on the techniques and results have been made since the beginning of the century. Today, smoke flow visualization continues to be a valuable technique for studying flow both in the classroom and in industry.

2. Introduction Smoke Flow visualization is an experimental means of examining the flow patterns around a body or over its surface. The flow is visualized by introducing dye, smoke or pigment into the flow in the area under investigation. The primary advantage of such a method is its ability to provide a description of the flow over a model without a complicated data reduction and analysis. Smoke- flow visualization (described by Bradshaw, 1970 and Rae and Pope 1984) involves the injection of streams of vapor into the flow. The vapor follows filament lines (lines made up of all the fluid particles passing through the injection points) in steady flow the filament lines are identical to stream lines. (Lines everywhere tangent to the velocity vector). Smoke- flow visualization thus reveals the entire flow pattern around a body.

It is difficult to exaggerate the value of flow visualization. The ability to see flow pattern on a model often gives insight into a solution to an aerodynamic problem. Flow visualization can be divided into two broad categories the first is surface flow visualization when the visualization media is applied to the surface such as tufts and oil flow etc. The second type is off surface such as smoke and streams. There are basically four methods of recording the flow visualization test. The first and the best but the least permanent method is for the scientist and the engineer to observe with his eyes. Because of the depth perception one can see a three dimensional picture. The other three common methods of recording the result of flow visualization are by film, either still or movie or television camera or video and magnetic tapes. It must be realized that all three of these methods are using a two dimensional medium to often record a three dimensional phenomena. This is especially fine when using a smoke or helium bubbles to trace flow stream lines pass the model. All three of these methods can be used either black and white or color. The photography methods while recording more time for developing and printing stills, when compared to video, yield higher resolution.

2.1 Objectives

Our objectives are as follows,

In this project we will study about how flow air in wind tunnel. Who is the responsible for changing direction of air? How many application of Smoke Flow Visualization System ? What is Smoke Flow Visualization System? Basic principle of Smoke Flow Visualization System. Properties of Wind Tunnel. Air passing system in Wind Tunnel. Measurement the effect of industrial smoke in environment.

2.2 Methodology

Our project methodology has arranged are as follows,

Basic ides about Smoke Flow Visualization System. Make a list of required parts. Collect the all required parts. Arrange the all parts according to instruction. After arrange check all connection. Run the project carefully. Observing the smoke line inside the glass made wind tunnel.

3. Application of the Smoke Flow Visualization System

Aerodynamics Fluid mechanics Heat Transfer

4. Smoke-Wire Wind Tunnel Design

Many designs have done in the past to optimize the use of smoke-wire flow visualization. In order to be able to view a variety of flows to maximize the usefulness of the tunnel, it is important to look at Reynolds numbers. Finding a range of velocities corresponding to the cross-sectional area of the wind tunnel is crucial. Ideally, we would like to achieve both laminar and turbulent flows around a given diameter cylindrical test object. The most interesting wind tunnels come when you can increase the velocities, and visualize flow separations, formation of vortices and backflows.

The airflow in the wind tunnel might need to be conditioned. Ideally, the air that passes through the smoke-wire and over the test object should be a constant velocity, parallel flow. Diffuser boxes, correctly designed, may need to be placed at the inlet and/or outlet of the wind tunnel. These are simply a gradual increase in area that will allow the flow to go through a smooth velocity change. This straightens the flow and makes the velocity less fluctuating where it matters: at the test object. Poorly designed diffuser boxes can be counterproductive, fluctuating the flow into unparallel, rough flows. Another method for conditioning flows which can be used along with diffuser boxes in the use of flow strengtheners. A popular flow straightening device is honeycomb, which is simply material of given thickness with thin parallel holes. It reduces the velocity of the flow and allows for a straighter, more conditioned flow. Other methods have been used, including bunching common drinking straws and placing them in the wind tunnel. The straws are orientated so that the air flows through the straws in a parallel manner. Anything that will allow the flow to be straighter at the test object then it is at the fan housing will produce better flow visualization results. The types of wire and liquid to coat the wire need to be optimized to fit the setup as well. Smoke that produces clearly visible, dense smoke lines are best. Lubricating and mineral oil will work well in most circumstances, but experiments have shown that Model Train oil produces the optimum smoke lines. That is, the lines stay in a dense stream for longer, and are easier to visualize and thus, photograph. Voltage and current through the wire need to be sensitively changed to produce the best results. Best results will lead to nice, visible smoke lines emanating continuously for about two seconds, which will be plenty of time to photograph the results.Once again there is a compromise that needs to be made. You cant gain something in engineering without sacrificing another. In order to get the densest smoke lines, the voltage needs to be at the highest possible without burning out the wire. However, the higher the voltage and the denser the smoke lines, the shorter the time of vaporization. Visualizing the flow requires an optimization of dense smoke lines, combined with enough time to adequately visualize and photograph the results. Combine that with different fan speeds and the entire setup is very sensitive.

5. Photographing Techniques

Photographing the specimen in wind flow visualization is perhaps the most important part of the setup. It is interesting to see the action of the smoke lines around the test object, but it isnt practical to do many experiments in a row. Also, two seconds is not a lengthy enough span of time for the observer to really see the results. For these reasons, photographing and videotaping play a crucial role in the experimental setup. The problem at hand, is finding a happy medium between shining enough light on the smoke lines to visibly see them, while maintaining a high contrast with the background. Doing this in a tight space constraint leads to a fairly sensitive setup which needs to be tweaked to optimization. Glare from the transparent wind tunnel sides (often glass or Plexiglas) will cause a large problem when trying to photograph the results.

The photographing setup and procedure is so sensitive to the setup itself (size of wind tunnel, lighting in the room, quality of smoke lines, object in question), and there are so many variables, that an optimal setup cannot be given here. However, types of lighting that have been used in the past that have provided good results can be explored. The two types of light that are used the most often are stroboscopic (strobe) and high intensity continuous lamps. Strobe lights are a popular way to light the smoke lines for photographing because they are fairly inexpensive and readily available. The length and intensity of the flash needs to be adjusted to the shutter of the camera or the framing speed of a video camera. Black and white film should be used to produce a high contrast to the smoke lines. A thin beam of light orientated along the wire and downstream is a practical way to illuminate the flow. However, in that orientation, there is a shadowed region behind the test object. As shown in figure 1, that area does not receive enough light to properly visualize flow. Another light needs to be orientated to properly illuminate that area. Some of the most critical flows that engineers want to be able to visualize occur in that shadowed area. Flow strengtheners, fans, and reflections from the sides of the tunnel make that a difficult obstacle to overcome.

Figure 1Example wind tunnel, showing shadowing A less practical, but very effective lighting innovation for use in wind tunnels has been the introduction of laser light. In fact, it is most likely the largest advancement to happen to smoke-wire flow visualization in the last 15 years. It is more expensive and requires delicate care due to its sensitive lens arrangements.

6. Experimental Setup:

FanVoltage sourceFigure 1Photo of Test wind tunnelHoneycombTest ObjectSlide ProjectorNicrome WireWith what was learned from research on smoke-wire smoke flow visualization from test, classes, and the Internet, testing was done using the 4 x 4 test wind tunnel shown in Figure 1 below. It is about 4 feet long, and is constructed of Plexiglas. The plastic 4 fan (12V, 0.9A) is placed at the outlet, making this wind tunnel work in the suction mode, pulling air through from left to right.

The test object at hand in the figure is a bright orange cylinder, of 2 diameter. The Nicrome smoke-wire is orientated vertically. A 4 x 4 x 2 piece of honeycomb was slide between the test object and the fan, to straighten the flow and reduce the velocity. Different honeycomb setups were investigated at the inlet, outlet, and both while also changing the distance from the test object and fan. The lightning in Figure 1 shows a slide projector on the right at the inlet of the wind tunnel. Although several lighting orientations were investigated, this seemed to give the best results. The slide in the projector is opaque with a thin vertical slit cut through. This sends a thin beam of light down the wind tunnel, along the wire, and downstream to illuminate the area in question. Problems did arise with shadowing from the test object, which will further be examined this spring.

Figure 2Side View of Smoke-WireSetupThe setup for the voltage source is shown in figure 2 (not to scale). Two diameter holes were drilled in the Plexiglas to pressure fit two polycarbonate plugs. The plugs have a small, thin metal tube running through the center. The wire is run through a plug, through the 4 wind tunnel test section, and out the other plug, assuring that the wire is in contact with the metal tubes, the voltage source is applied via alligator clams to the metal tubes. The advantage of this is that the wire is free to be slid out, oil to be applied, and slid back in place, without disconnecting the alligator clamps. The smoke naturally flows up because it is lighter then air, so in order to get parallel, horizontal smoke-lines, it is crucial to only apply the voltage to the wire once the fan has been turned on and there is a constant air flow in the tunnel. Because I was using one voltage source with one on-off switch, but with two connections, it was tricky to be able to have the fan on before the voltage was applied to vaporize the oil. I had to physically plug in the voltage to the voltage source in the on position. This setup is almost exactly to the setup that will be used for the final design. The new wind tunnel will be larger however. It will be 6 x 6 cross-sectional area and about 6 long. This length includes a diffuser box and a fan casing at the outlet. We will diffuse to a 8 x 8 cross-sectional area which houses a 6 diameter fan. Honeycomb will be placed in strategic locations if needed. Lighting orientations will be examined further once the final design is constructed. The current oil application technique will most likely be used as well. The wire is held taunt by tying the bottom end to a weight. Currently, that weight is a wrench but will be more attractive on the final design. A tightening crack method will be investigated in the spring. Ideally, the wind tunnel will be transferable to be able to place it in classroom to study Fluid Dynamic and other principles. However, if the lighting and photographing techniques are too sensitive to change, it will be setup downstairs in N007 and left there.

7. Discussion: After studying various visualization techniques in a variety of mediums, I have decided that the best system for this experiment is smoke-wire flow visualization in a wind tunnel. The setup will be used to study flow patterns around objects to learn the concepts and the theories of fluid mechanics, heat transfer, and aerodynamic principles in general. This system will consist of an inexpensive setup, that is easy to produce and easy to run, that can be used in classrooms. Brainstorming the optimal system setup will follow from the materials used and the chosen size of the system. Ideally, it should be easily moved and reconstructed to be placed anywhere for demonstration. If the lighting orientation is too sensitive to change, then perhaps it will not be transferable. There were a number of qualities of the smoke-wire flow visualization system that made it the obvious choice for the desired setup. The most apparent was the price and availability of the materials involved. The wire that can be used is a common wire that can be purchased anywhere. Model train oil, which can be picked up at any hobby store, produces the best results. A Plexiglas wind tunnel fit around a plastic fan is effective, easy to assemble, and durable. Standard Aluminum can be used to make the diffuser boxes and fan casing. With all of the materials purchased and assembled, the design of rest of the system depends on the results. A damping system will most likely need to be added to straighten the flow before it hits the smoke-wire, and the photographing setup will be tested in a variety of positions. For the most part, it is a simple setup with readily available materials that produces great results. The main motivation for this project came from the failure to produce good flow visualization in the Blue Wind Tunnel for the term project in Fluid Dynamics class (ME who knows?). A Frisbee was placed in the wind tunnel at different attach angels and velocities and the lift and drag were analyzed. The project was a complete success, but any attempts to visualize flow were unsuccessful. The addition of foreign substances into the airflow were examined, including smoke from incense sticks, and small pieces of foam. Unfortunately due to time constraints, the project was finished without ever getting good flow visualization around a Frisbee. This wind tunnel will be able to do just that. Students and professors can take a common object, perhaps on a smaller scale, and view the flow in and around it. It will be able to be used by classrooms with relative ease, and produce results in a quick, effective manner. Photographing can be done in order to aid in the presentation of the material in a written lab form, or in presenting to engineering students in the future.

8. Progress Forecast:

With what was learned from research and testing from the 4 x 4 wind tunnel, a 6 x 6 cross-sectional area wind tunnel will be constructed. Comparable oil application will be used on this tunnel as was used with the test tunnel. Improvements however will come with accessibility to the wire, and repeatability of results.

Figure 3Wind tunnel SchematicThe new wind tunnel (Figure 3) will be larger both in length, and in cross-sectional area. It will be primarily made of Plexiglas, but contain an aluminum diffusing box at the outlet. There will be three possible wire placements, corresponding to three polycarbonate plugs at the top and the bottom of the tunnel. The front panel, which will be viewed through to observe the air flow, will have a removable slab of Plexiglas. This will serve as a place to interchange test objects, repair any unforeseen difficulties with the test section, and also be a convenient place to clean the Plexiglas easily. Lighting and photographing techniques, not chown in the figure, will be optimized to produce the best flow visualization results. This project, properly designed and optimized, will produce repeatable, high quality flow visualization around a variety of test objects. It will be able to be used in classrooms to show engineering students first hand, the principles and concepts of fluid dynamics, heat transfer, and aerodynamics. Photographs can be taken to aid in the presentation of the material both in the written form, and in aural presentation. Well into the next millenium, with proper maintenance, fluid dynamics classes will use this tunnel along side the text as a teaching aid, making our department and its resources even more valuable then it is presently.

9. Recommendations If the wind tunnel too much slander, it is not enough comfortable for observing. If the speed of air flow in the wind tunnel is so much it can radius its performance. The limited flow of air in the wind tunnel should remain at the time of observation. For taking photography needed dark room with high regulation camera. For better understanding should use PaintShop Pro 5 softwere. It should need a honeycomb or a safety net.

10. Conclusion:

I would like to mention that in thermodynamics are we lucky, in that the subject in question is so easily visualized. Applications for the use of flow visualization are virtually endless, requiring a wind range of visualization techniques. Beautiful, fascinating, and captivating visions of flow in nature are out there waiting for engineers to visualize. Addition of a foreign agent into the flow field, proper lighting and photographing techniques, and the drive to understand nature has helped to fill in the gaps of previously unknown fluid dynamic principles.

In twelve weeks, a great deal was learned about the importance of flow visualization, the techniques used to visualize flow, and in particular, smoke wire flow visualization. In just a few minutes, visualization can be done at low speeds around a variety of different test objects. Qualitative results can explain principles found in nature as well as explain the theories behind new technologies such as aeronautics. Quantitative data can be taken in the form of Reynolds numbers to help to standardize the procedure as well as compare to what others have done in the past.

The setup has its limitations as previously discussed. However, for its application, smoke-wire flow visualization is a dependable, repeatable, and efficient way to help engineers understand the principles of fluid dynamics, heat transfer, and aerodynamics in general. With the design and development of a transport cart to mount the finished wind tunnel to, the entire system will be easily brought in and out of classrooms and labs to aid students and teachers alike. Now, a useful supplement is found to be used with text to hopefully strike increasing interest in teachers and students who will drive us into the technologically unknown future.

11. References:

I. Bradshaw, P., Experimental Fluid Mechanics. pp 142 161. Pergamon Press, Oxford. 1964.

II. Merzkirch, Wolfgang, Flow Visualization (Second Edition). Academic Press, Inc., Orlando. 1987.

III. Van Dyke, Milton, An Album of Fluid Motion. Parabolic Press, Stanford, California. 1982.

IV. Yang, W.-J., Werle, H., Mueller, T.J., Reznicek, R., Moffat, R.J., Kasagi, N., Hirata, M., Crowder, J.P., et al. Handbook of Flow Visualization (Wen-Jei Yang editor). Taylor & Francis, 1989.

V. Preliminary Design of an Intermittent Smoke Flow Visualization System By Donald T. Ward and James H. Myatt

VI. World Wide Web.

December 8, 2012