On Particle Image Velocimetry (PIV) Measurements in the Breathing Zone of a Thermal Breathing Manikin

1. On Particle Image Velocimetry (PIV)Measurements in the Breathing Zoneof a Thermal Breathing Manikin D. R. Marr, T. A. Khan, M. N. Glauser, H. Higuchi, Jianshun Zhang, ASHRAE Trans., vol. 111, pt. 2, paper no. 4813, p. 299-305 Srikar R Kaligotla SU# 206365487 MAE-741

2. What is PIV? • Particle Image velocimetry (PIV) is a measurement technique for obtaining instantaneous whole field velocities. The flow field is made visible by naturally buoyant tiny particles/markers (seeding) that follow the flow. Velocity measurement is accomplished by measuring the motion of the small markers in the fluid. • The local velocity is then estimated from the fundamental definition of velocity : u( x, t ) = [x( t + dt) – x(t)] / dt Where x(t) and x(t+dt) are the spatial locations of a marker at time t and (t + dt) respectively, dt being a short time interval.

3. PIV Principle Basic Principles : 1. Flow Visualization a. Seeding b. Illumination 2. Image Recording a. Cameras b. Synchronization 3. Image Analysis a. Correlation techniques b. Validation and further analysis fig-1 PIV Principle

4. Introduction • A time-resolved PIV system has been employed to obtain quantitative velocity vectors in the breathing zone (nose only, fig-4). • Phase averaged (with breathing cycle) velocity measurements were taken in a vertical plane down the center of the manikin face. • The research presented in this paper includes measurements taken in a vertical plane along the face of a thermal breathing manikin using a TRPIV system. • The results from this research provide insight on the transport phenomenon occurring around persons in the indoor environment with breathing and can be used for CFD validation • The primary focus of this referenced work is part of a larger study including aerosol spatial distribution, ventilation effectiveness, and aerial contaminant control strategy development.

5. Experimental Setup fig-2 IFL Chamber fig-3 TRPIV system • IFL chamber ( dimensions- 12x16x10 ft) • Hans Rudolph Simulator ( series 1120 flow simulator in use, capacity - 8.5 ltrs, flow capability of 16 ltrs/sec) • 17 Zone heated Manikin( Watlow and Watview) • DANTEC Dynamics TRPIV system (Nd:YAG laser of wavelength 532 nm).

6. Manikin Temperatures Table-1 Thermal Manikin Surface Temperatures

7. Adaptive Correlation Technique • Adaptive correlation is used for the velocity computations which essentially is an extension of cross correlation technique. • The cross functions may be expressed as follows. Where f and g are the intensities of light within the interrogation area recorded at time t and t+dt , denotes the interrogation area and (k, l) & (m, n) describe image co-ordinates.

8. PIV Results • Using an adaptive correlation, they were able to reduce in-plane drop out, or particles that travel outside the correlation window. To compensate for this signal loss, the correlation software searches for particles into a specified percentage of the surrounding windows. • This adaptive correlation also inserts velocity vectors in locations where none were measured using an averaging technique. • Approximate Error ranges from 1.6% to 1.9%. (from the references Zhao et al. (1998) and Riskowski et al. (1993).

9. PIV Results • Since they were dealing with the unsteady flow and the unchanging PIV burst interval time, an optimal burst time is difficult to set that minimizes the error associated with the analysis. • Hence Laskin Atomizer was used. (here air is blown in to a pressurized line into reservoir liquid creating droplets 1-10 microns in diameter).

10. Breathing Cycle fig-4 Instantaneous PIV snapshot fig-5 Average Breathing Waveform

11. Phase Average approach • Averaging is achieved by breaking the breathing cycle in to 25 different slices. This type of averaging is useful for identifying the unsteady structure of mean flow. • The Equation for the turbulent intensity. • Where

12. Results and Conclusions fig-6 Thermal buoyancy in the breathing zone (maximum velocity 0.03 m/s, spatial scales are in mm)

13. Results and Conclusions fig-6 timestep 1( Max- vel =0.11m/s spatial scales in mm) fig-7 timestep 2 ( Max- vel =0.13m/s spatial scales in mm) fig-9 timestep 4 ( Max- vel =0.2m/s spatial scales in mm) fig-8 timestep 3 (Max- vel =0.16m/s spatial scales in mm)

14. Combination

15. Turbulence Intensity • The TI looks to be greatest (fig-10) in the region of exhaled air while the largest velocity vectors lie slightly lower as part of the thermal plume created by the thermal manikin. fig-10 Local turbulence intensity (window size same as in Figures 5-9).

16. References Papers: • Khan, T.A., H. Higuchi, D.R. Marr, M.N. Glauser. 2004. Unsteady Flow Measurements of Human Micro Environment Using Time Resolved Particle Image Velocimetry. Proceedings of ROOMVENT 2004, 9th International Conference on Air Distribution in Rooms, Coimbra, Portugal, 5 – 8 September. • Marr, D.R., R., Sheth, M.N., Glauser, H. Higuchi. 2005. A PIV Analysis Around a Thermal Breathing Manikin. Proceedings of 2005 ASME conference Orlando, FL, 6-11 Nov 2005. • Marr, D.R., T. Khan, M. Glauser, H. Higuchi. 2004. Velocity Measurements Along the Average Breathing Waveform. Proceedings of the 1000 Islands Fluid Dynamics Meeting, Gananoque, Ontario, Canada. Web: • http://www.dantecdynamics.com/Download/pdf_files/pi800307.pdf

17. QUESTIONS??