Final Report for RERF proposal titled

High-sensitivity, High-speed Camera

Submitted to the

Research Office

Oregon State University, Corvallis

by

Vinod Narayanan

Associate Professor, Mechanical Engineering

Oregon State University

May 10th, 2012

 

 

 

Summary The RERF proposal titled “High-sensitivity High-speed Camera” requested funding to the tune of $21,675 for acquisition of a high-speed camera (Vision Research Phantom v310). In addition, matching funds totaling $23,045 from two current NSF projects was used towards the acquisition. The camera was delivered in April 2010. Over the past 2 years, it had to be sent twice to the company for repairs, but is in working order now. Three current projects- two funded by NSF and one by NASA are benefitting from the acquisition. One PhD student and 1 MS student have graduated using data obtained from the camera, while another PhD student and two MS students are currently using the camera for their research. Recently, the camera was used to gather high-speed videos in a fluid physics microgravity flight experiment sponsored by NASA.

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Context Support for procurement of a state-of the-art high-speed camera from Vision Research, Phantom v310, was requested. The camera is being used for a phenomenological understanding of phase-change (boiling and condensation) heat transfer and fluid flow. Phase-change heat transfer is of great importance in several applications such as in (a) cooling of electronics, high power electrical systems, and avionics, (b) refrigeration and air-conditioning, (c) phase-change chemical operations such as absorption and desorption, and (d) propulsion systems components such as rocket combustors and injectors. NASA has recognized that the inability to fully understand boiling processes in microgravity is a key bottleneck to increased levels of power generation that is vital for space exploration [1]. For development of energy-efficient new designs of devices for the above applications, it is crucial to identify the fundamental processes that govern phase-change as well as to enhance these processes. Current numerical simulations are unable to capture several events associated with the boiling process, the most important of these being bubble nucleation. This has necessitated development of phenomenological models to predict boiling flows. The boiling process is associated with high frequency events such as bubble nucleation, bubble growth and release from the surface, multiple bubble interactions and bubble oscillations. The time scales of these events are typically in the order of milliseconds all the way to tens of microseconds (10-3 s to 10-5 s). These events need to be documented as well as interpreted along with other data such as surface temperatures, fluid temperatures, and fluid velocity around bubbles, in order to determine the different forces that play a role in phase-change processes. The procured high speed camera is helping us document such short time scale phenomena. Timeline The camera was delivered in April 2010. A technical representative from the company stopped over to train us on use of the camera. Examples of Camera Use in Research Over the past two years, information gathered from the camera has elevated the quality of our research and findings. Data and image sequences from the camera have already been used in one PhD dissertation and 1 MS thesis. Five archival journal publications [2-6] and seven conference papers also present images and video sequences recorded using the camera. Three projects namely jet impingement boiling, self-cavitating jet thermally actuated pumping currently make use of the camera presently. In jet impingement boiling research, the camera images and video sequences are being used to qualitatively supplement heat transfer data. Ongoing work will aim to use high speed image sequence of bubble growth and departure from a single site to determine the growth rate and bubble size and help develop phenomenological models of the impact of jet inertia on the bubble dynamics. Figure 1 shows a sample video sequence of jet impingement boiling research recorded using the v310 camera. The high-speed camera is being used to both qualitatively and quantitatively visualize the phenomenon of self-cavitation in a modified circular nozzle. Both free jet and impinging jet configurations are being studied. High speed videos will be analyzed using image processing methods developed by the PI [7] in order to determine the dominant structures and periodicity of

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the cavitation cloud. Figure 2 shows an example of the cavitation cloud recorded by the high-speed camera [8].

(Ia) t=0.000 s

(Ib) t=0.026 s

(Ic) t=0.148 s

(Id) t= 0.341 s

(Ie)t= 0.510 s

(If) steady state at incipience

heat flux

(IIa) t=0.000 s

(IIb) t=0.028 s

(IIc) t=0.057 s

(IId) t=0.085 s

(IIe) t=0.142 s

(IIf)steady state at incipience

heat flux Figure 1: Example of use of high-speed camera in jet impingement boiling research. Boiling progression at incipience for (I) a scenario of low incipience temperature overshoot- dj=3.96 mm, Re= (II) a scenario of high incipience temperature overshoot at ∆Ti=27.5 oC - dj = 1.16 mm, Re=12484. Note that t=0.000 corresponds to the first frame of the movie sequence for scenario I and inception for scenario II. The bright areas on the surface correspond to fluid in contact with the polished copper surface.

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0s 

 

100 µs 

 

200 µs 

 

300 µs 

 

400 µs 

Figure 2: Example of use of high-speed camera in self-cavitating jet research. High-speed visualization of a bubble cloud emanating from the self-cavitating nozzle using subcooled water.

In the thermally actuated pumping project, the camera is the primary means of extracting quantitative data and developing phenomenological models. The goal of the project is to demonstrate that if the microstructure of a heated surface that needs to be cooled is engineered appropriately, bubbles departing from the surface could pump the cooling fluid without the need for an pump. Figure 3 shows an example of high speed images taken using the camera and how these images are used to determine bubble and fluid velocities. During the first week of May, the camera was used to document boiling phenomena associated with thermally actuated pumping in microgravity in a fluid physics flight experiment sponsored by NASA.

Figure 3: Example of use of high- speed camera in thermally actuated pumping research. (a)- (g) Sequence of high speed images in near and far field (h) Bubble velocity vector corresponding to (d) - (g)

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Current Support Related to this Acquisition

1. Current: “CAREER: Enhanced Two-phase Thermal Management Using Self-sustained Flow Oscillations at the Microscale,” PI, National Science Foundation, June 15, 08 – May 31, 2013.

2. Current: “Collaborative Research: Thermally Actuated Pumping Mechanism During Boiling on Asymmetrically Structured Surfaces,” PI (with S. Bhavnani); June 1, 09 – May 31, 2013.

3. Current: “Boiling Heat Transfer Mechanism During Thermally-actuated Pumping by Asymmetrical Surface Structures,” (with S. Bhavnani); June 1, 09 – September 30, 2012.

References 1. Committee on Microgravity Research, Division of Engineering and Physical Sciences,

National Research Council, 2003, Assessment of Directions in Microgravity and Physical Sciences Research at NASA, National Academies Press, Washington DC.

2. Thiagarajan, N., Kapsenberg, F., Narayanan, V., Bhavnani, S. H., and Ellis, C. D., “Development of a heat sink with periodic asymmetric structures using gray-scale lithography and deep reactive ion etching,” Electron Devices Letters, submitted February 6th 2012, accepted April 20th 2012

3. Cardenas, R., and Narayanan, V., 2012, “Heat Transfer Characteristics of Submerged Jet Impingement Boiling of Saturated FC-72,” International Journal of Heat and Mass Transfer, published online April 2012, DOI-10.1016/j.ijheatmasstransfer.2012.03.063

4. Cardenas, R., and Narayanan, V., 2012, “Critical Heat Flux in Submerged Jet Impingement Boiling of Water at Sub-atmospheric Conditions,” ASME Journal of Heat Transfer, in print.

5. Mani, P., Cardenas, R., and Narayanan, V., “Comparison of area-averaged and local boiling curves in pool and jet impingement boiling,” Int. J. Multiphase Flow (2012), doi:10.1016/j.ijmultiphaseflow.2012.02.002

6. Cardenas, R., and Narayanan, V., 2012, “Submerged Jet Impingement Boiling of Water Under Sub-atmospheric Conditions,” ASME Journal of Heat Transfer, 020909, Vol. 134, pp. 020909-1-9.

7. Narayanan, V., Lightfoot, M. D. A., Schumaker, S. A., Danczyk, S. A., and Eilers, B., “Use of Proper Orthogonal Decomposition Towards Time-resolved Image Analysis of Sprays,” ILASS Americas, 23rd Annual Conference on Liquid Atomization and Spray Systems, Ventura, CA, May 2011.

8. Cardenas, R., Mani, P., Narayanan, V., Dokken, C., 2012, “On the elimination of temperature overshoot during jet impingement boiling of highly wetting fluids,” Paper #1466, ECI 8th International Conference on Boiling and Condensation Heat Transfer, Ecole Polytechnique Federale de Lausanne, 3-7 June 2012.