A Sample of PIV Applications Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated PIV Applications Measuring “micro-flows” Studies of turbulence structure Unsteady or periodic flows Capture transient flow details Complex steady flow fields Extremely low velocity flow fields Spatial gradients (at thousands of points) of instantaneous and average flow properties Obtaining global nature of flows Examining spatial interdependence of flow properties PIV is particularly useful for diagnosing unsteady flows. Latent turbulent structures can be unmasked with PIV whereas averaging techniques (like LDV) tend to wash out the structure. In periodic flows, such as IC engines, and turbines, entire flow field information can be obtained for each phase angle. Even in steady flows with complex geometry (e.g. flow around rod bundles) whereas access may be difficult, PIV can be a useful tool. Time averaged velocity and turbulence values at each point in the flow field can also be obtained with PIV when a sequence of frames are analyzed. PIV has been used to measure flows ranging from low velocity natural convection flows all the way to supersonic flows. Applications include measurement in two phase flows, combustion flows, rotating machinery flows, biological flows, wind/water tunnel flows, flow in between rotating disks, etc. Copyright© 2002 TSI Incorporated

MicroPIV Stereoscopic arrangement The TSI Micro-PIV optical lens assembly is designed to be used in PIV measurements for region smaller than 1 mm, such as micro channels and MEMS devices. The major components included with the assembly are the long working distance microscope objective, the relay lens, the microscope body with traverse mechanism, the camera mount and the fluorescent optical filter. The assembly can be used with any one of the TSI PIV cameras, the PIVCAM series and the PowerView series of cameras. Since the camera is mounted with the assembly as a single system, it provides great flexibility in positioning the system to adapt with the flow model. Additional traverse mechanism could be used to allow fine positioning of the system. Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Micro PIV System The objective lens, nearest the subject under observation, provides a magnified real image of the object. The relay lens functions in a way similar to the eyepiece found in a compound microscope. The eyepiece magnifies the real image provided by the objective lens, and yields a virtual image appropriate for the human eye. In the case of the micro PIV assembly, however, the CCD camera plays the role of the human eye. The microscope focusing body is provided as a solution to the focusing procedure. Depending on the desired magnification, the user can choose an appropriate objective lens. The working distance depends on the magnification factor and the bigger the magnification the smaller the length of the working distance. The main advantage of objectives with large working distances is that they can accommodate incident illumination from above the subject under investigation. TSI microPIV system allow more space and flexibility on accessing the flow apparatus. To obtain successful measurements in a micro flow field, it is necessary to use seeding particles that emit light at a different wavelength than that of the laser. The reason is that reflection from the subject will be very strong that the scattered light overwhelms the particle images on the CCD camera. Therefore, fluorescent particles on the order of 1μm are used as tracers in the vast majority of the micro PIV applications. These particles absorb the green illumination light (λ = 532 nm), and emit a distribution of red light with a peak emission taking place at λ = 610 nm. The emitted light is imaged through the objective and the relay lenses and passed to a high pass optical filter (>550 nm), where the green light from background reflections is filtered out and the red fluorescence from the micron particles is recorded onto the PowerViewTM CCD camera. Copyright© 2002 TSI Incorporated

Measurements in a “microchannel” 800 mm 800 mm Copyright© 2002 TSI Incorporated

Microchannel measurements Width of the channel 100 microns Depth of the channel 30 microns Objective lens x50 PIVCAM 10-30 Fluorescent Particle 0.3 micron diameter Flow: Pressurized - using syringe pump Kobayashi, Taniguchi Oshima Lab University of Tokyo Copyright© 2002 TSI Incorporated

Dual-plane stereoscopic PIV system Image recording system Camera 3 Schiempflug condition Mirror Camera 2 250 Vertically polarized laser sheet (S-polarized light) Polarizing beam Splitter cube Camera 1 Horizontally polarized laser sheet (P-polarized light) Lens plane Image plane Camera 4 To laser system Synchronizer Courtesy: University of Tokyo Copyright© 2002 TSI Incorporated

Dual-plane stereoscopic PIV system Illumination system 7b 8b 5b 10a Laser tube 1 Laser tube 2 Laser tube 3 Laser tube 4 9a 6a Mirror 12 9b 6b 10b SHG Polarizer 13 Mirror 15 Cylinder lens 14 V(s) H(p) V (s) Double-pulsed Nd:YAG laser set A Nd:YAG laser set B Courtesy: University of Tokyo Copyright© 2002 TSI Incorporated

Velocity field – Lobed Nozzle Three dimensional velocity vectors Isosurface velocity vectors Courtesy: University of Tokyo Copyright© 2002 TSI Incorporated

Microgravity measurements Combustion in Microgravity Courtesy: CNRS Orleans Copyright© 2002 TSI Incorporated

Microgravity measurements Combustion in Microgravity Powerview PIV system Field of view 51mm Fuel injected through a tube of 4 mm diameter Mean velocity field and a typical image field are shown above Image field Velocity field Courtesy: CNRS Orleans Copyright© 2002 TSI Incorporated

Biomedical flow Measurements in a simulated heart chamber Flow in heart chamber Twin mini YAG lasers 1K x 1K cross correlation camera 15 frames/sec Water-glycerin flow Seeding- glass spheres Courtesy: University of Miami Copyright© 2002 TSI Incorporated

Rotating Machinery Flow in a high-speed compressor Improving the efficiency of in turbomachines requires understanding the flow field occurring within rotating machinery. Although average flow field measurements provide a great deal of insight into the performance of the machines, there are many unsteady flow phenomena occurring in the complex flow fields encountered in turbomachines which may significantly impact the steady state flow. The instantaneous planar velocity measurements obtained with PIV make it an attractive technique for use in the study of the complex flow fields encountered in turbomachinery. Measurements using a Nd:YAG laser based PIV system have been carried out in a single stage 50.8 cm diameter transonic axial compressor facility at NASA Lewis. Measurements were obtained in the blade to blade rotor passage (36 blades) at a rotational speed of 17,128 rpm. Under these operating conditions a shock wave forms off the blade leading edge. A bow wave also forms off each blade extending outward from each blade tip. A specially constructed light sheet delivery system using a periscope type configuration was employed to illuminate the flow region in the rotor passage. A 1K x 1K pixel cross-correlation CCD camera utilizing the frame straddling technique was used to acquire the particle images. A once-per-rev signal on the rotor was used to trigger image acquisition and laser pulse triggering. The camera image acquisition and laser pulsing were all software controlled through the Synchronizer. Courtesy: NASA - Lewis Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Rotating Machinery Dual YAG lasers with about 125 mJ/pulse was used with the light arm Camera: PIVCAM 10-30 1018 x 1018 pixels at 30 frames/sec TSI Model 610032 Synchronizer Analysis: Cross-correlation analysis using InSight-NT analysis package The velocity vectors are color coded by vector magnitude. The results from the measurement are shown in absolute velocity and the position of the blade to blade plane shock is readily observed by the sharply turning vectors in the figure. Courtesy: NASA - Lewis Copyright© 2002 TSI Incorporated

Rotating machinery flow measurement region x y Dual Mini-YAG lasers PIVCAM 10 - 30 1K x 1K crosscorrelation camera TSI Model 610032 Synchronizer Water droplet as seed particle Phase-locked image capture Batch-mode analysis of data, phase averaged mean velocity fields Simultaneous PIV-LDV measurements PIV measurements in the cross-sectional plane at different axial locations Copyright© 2002 TSI Incorporated

Periodic swirling flow Phase-locked PIV measurements Average velocity field Z=1 Z=10 Flow in the exit plane of a fan was measured by doing phase-locked image capture and batch-mode analysis. The figure shows the contours of the velocity magnitude obtained by phase-averaging. Copyright© 2002 TSI Incorporated

IC Engine PowerView PIV Measurements A two component PowerView PIV system was set up on a motored Gasoline Direct Injection (GDI) internal combustion engine such that the light sheet formed a vertical slice through the diameter of the cylinder. The PIVCAM 10-30 digital camera was oriented perpendicular to the light sheet and phase-locked images were captured at multiple crank angles. A once-per-revolution signal from the engine was used to trigger the synchronization electronics of the PIV system. Olive oil that was atomized using a 9307 oil droplet generator and fed in through the intake port of the engine was used to seed the flow. The goal of the experiments were to quantify the flow fields as various crank angle positions during the intake and compression strokes. Mixing of the fuel was of great concern as it greatly effects the performance of the engine. Two intake port configurations were used: 1) an unmodified, dual valve intake port configuration ; and 2) swirl generators added to the intake ports upstream of the valves. Courtesy: MSU Copyright© 2002 TSI Incorporated

IC Engine PowerView PIV Measurements These results show the phase-averaged results from a GDI motored engine with unmodified intake ports. A total of 50 phase-locked measurements at each crank-angle position were used to compute the averaged flow fields. The movie shows phase-average velocity fields at various crank-angle positions. The color of the vectors if proportional to the local vorticity and the total circulation for each phase-averaged velocity field is shown to the right in each frame. Note that a relatively strong coherent structure forms in the left hand portion of the flow field downstream of the intake valves. Mixing appears to be significant during the intake portion of the engine stroke. However, the flow field is relatively “quiet” during the compression stroke and further mixing appears to be subdued. When swirl generators were added to the intake ports, a large scale vortex persists throughout the intake and compression stroke. As a results performance of the engine was enhance due to the increased mixing. Courtesy: MSU Copyright© 2002 TSI Incorporated

GDI Internal Combustion Engine PowerView PIV Measurements For the unmodified and modified intake port cases, the total circulation was computed for each of the phase-averaged velocity fields and plotted against crank angle. For the modified intake port case, the circulation was significantly enhanced when compared to the unmodified case. Hence, there is a strong correlation between circulation and how well mixing occurs inside the combustion chamber and how well the engine performs. Courtesy: MSU Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Flow in an IC Engine The very first PIV system supplied by TSI was used for measurements in an IC engine In-cylinder flow in an IC engine, Velocity around 30 m/s, 5000 vectors, large format camera. PIV is ideal for a periodic flow such as in the IC engine. Image capture of the entire region is accomplished for various crank angle positions. The image fields obtained at one angle can then be ensemble averaged. Most of these experiments are done in motored engines. Optical access is a challenge. Transparent pistons or heads are generally required. For measurements in firing engines seed particles that can survive the temperature are required. Metal oxides (Titanium dioxide, for example) are often used for seeding. Courtesy: General Motors Copyright© 2002 TSI Incorporated

Measurements in an IC Engine 50 mJ/pulse dual YAG laser is used for studying the flow in the cross section of a motored IC engine. The cross section is imaged through a transparent piston. The swirl velocities in the CS plane are around at m/s. Metal particles (less than 5 microns) are used for seed. 1KX1K cross correlation camera is used with a Dt = 5 microsecond. The small time interval is required to capture image pairs when there is strong out-of-plane motion. Copyright© 2002 TSI Incorporated

Helicopter rotor wake StereoPIV measurements Courtesy: University of Maryland Aerospace Engineering Copyright© 2002 TSI Incorporated

Helicopter rotor wake StereoPIV measurements Courtesy: University of Maryland Aerospace Engineering Copyright© 2002 TSI Incorporated

Helicopter rotor flow Stereoscopic PIV Measurements Courtesy: University of Maryland Aerospace Engineering Copyright© 2002 TSI Incorporated

Helicopter rotor flow Stereoscopic PIV Measurements x component of velocity Vorticity field Courtesy: University of Maryland Aerospace Engineering Copyright© 2002 TSI Incorporated

Measurements in flames Flame stabilization is an issue of considerable importance to turbulent combustor design. Investigation of the flame stabilization mechanisms are carried out using a Nd:YAG based PIV system. The 532 nm output of the laser is formed into a 250 mm thick light sheet and passed through of the test section. Particle images were captured using a 1K x 1K CCD camera. The velocity vector field and associated flow properties are calculated from the particle image displacements. Figure shows the instantaneous velocity vector field in a lifted, turbulent CH4 jet flame at a Reynolds number of 7000. The region enclosed by the solid red line and originating from top of velocity vector field indicates high temperature flame zone. The most upstream location of the high-temperature region defines the flame stabilization point. It can be seen the velocities near the flame stabilization point are significantly reduced and typically less than 0.4 m/sec. in the vector field shown. The velocity field in a lifted, turbulent CH4 jet flame was studied over a range of Reynolds numbers from 7000 to 20,000. Courtesy: Sandia Labs Copyright© 2002 TSI Incorporated

StereoPIV Measurements in a Flame Experimental Setup 120 mJ Dual Mini-YAG lasers with Light Arm with light sheet optics Two PIVCAM 10-30 cameras Parallel processing (Quad Processor System) Computer-controlled Synchronizer (Model 610034) High speed interface (Model 600067) on-line transfer of data from camera at the highest camera frame rate INSIGHT Stereo Data Analysis Package Three-component velocity measurements are made in different vertical planes. z = 0 corresponds to the diametrical plane of the jet. Han, Su, Menon and Mungal (Lisbon 2000) Copyright© 2002 TSI Incorporated

Instantaneous vs. Average Han, Su, Menon and Mungal (Lisbon 2000) Copyright© 2002 TSI Incorporated

Lifted-jet Flame Stereoscopic PIV Measurements Z = 10mm plane Center plane Turbulent kinetic energy Han, Su, Menon and Mungal (Lisbon 2000) Copyright© 2002 TSI Incorporated

Industrial spray burner StereoPIV Measurements Palero, Ikeda, Nakajima and Shakal (Lisbon 2000) Copyright© 2002 TSI Incorporated

Measurements in a Plume Ultrahigh resolution PIV Measurements Courtesy: MIT Copyright© 2002 TSI Incorporated

Measurements in a Plume Ultrahigh resolution PIV Measurements Courtesy: MIT Copyright© 2002 TSI Incorporated

Bubbly two-phase flow Two-camera Arrangement Copyright© 2002 TSI Incorporated

Bubbly two-phase flow Two-camera Arrangement Air Water Copyright© 2002 TSI Incorporated

Flow around a robotic fruit fly Courtesy: University of California, Berkeley Copyright© 2002 TSI Incorporated

Pressurized Water Reactor Velocity field Vorticity field CFD Results PIV Measurements Stefanini, Mignot, Saldo, Baroi and Conte (Lisbon 2000) Copyright© 2002 TSI Incorporated

Cylindrical Couette Flow Copyright© 2002 TSI Incorporated

Atmospheric Boundary layer Measurements 2m x 2m Field of view 4 PIVCAM cameras Courtesy: University of Illinois Copyright© 2002 TSI Incorporated

StereoPIV Measurements Pier Measuring region Measurements were made in a horizontal plane downstream of a cylindrical pier. Water flow measurements. Courtesy: S. Dakota State University Copyright© 2002 TSI Incorporated

Flow Behind a cylindrical pier Stereoscopic PIV Measurements POWERVIEW Stereoscopic PIV System Model 610032 Synchronizer Two PIVCAM 10-30 Cameras - 30 frames/sec (each) Scheimpflug Stereoscopic Arrangement INSIGHT-Stereo Data Analysis Package U component W component Courtesy: S. Dakota State University Copyright© 2002 TSI Incorporated

Measurements in a spray Copyright© 2002 TSI Incorporated

Gravity waves StereoPIV Measurements Lengrich, Graw and Kronewetter (Lisbon 2000) Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Channel Flow This is one of the early applications of PIV. Uniform water channel flow, 1850 vectors, Dual YAG, 35 mm film, Mirror image shift, 1 m/s. PIV is an ideal technique to unmask hidden turbulent structure. In a relatively simple channel flow, one can subtract the global mean value to look at the structure of turbulence. Time averaged techniques such as thermal anemometry and LDV cannot provide such detail. (Note: Mirror image shifting is a way of introducing an artificial displacement of the second image. This is used with autocorrelation analysis approach). Courtesy: University of Illinois Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Flow in a cavity Data Courtesy of Sandia National Laboratory. Slide shows a two dimensional water channel with a square cross section cavity in the lower surface. Illumination: Continuous Argon laser light sheet Camera: TSI PIVCAM 4-30 analog CCD camera 1024 X 1024 pixel resolution, 15 frames/sec Field of View: Approx. 40 mm X 30 mm t: 33 ms Seeding: Unknown Processing: Two frame cross correlation Shows velocity vectors overlaid on contours of velocity magnitude. Data output is from TSI InSight-NT software. Raw image field Velocity vector field Courtesy: Sandia Labs Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Swirling Flow in a Pipe 100 mJ/pulse dual YAG is used to measure in the cross-section of the pipe. Axial velocity is around 20 m/s. The cross-section velocity is around 3-5 m/s. The image is captured using a mirror at the bottom of the pipe. RS170 CC camera is used to obtain the images. Copyright© 2002 TSI Incorporated

Measurements in a steady Jet Flow This slide shows an example PIV image with calculated velocity vectors overlaid. The flow is circular jet. The power of PIV to capture the transient vortex structure is clearly shown. Measurements were made in an air-jet using water droplets as seed particle. The images were captured by a PIVCAM 10-30 camera. Crosscorrelation analysis was used to obtain the velocity field. Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Sonic jet Data courtesy of NASA Lewis center Slide shows a sonic jet flow. Illumination: Dual Nd:YAG, 400 mJ/pulse Camera: TSI PIVCAM 10-30 1024 X 1024 pixel resolution, 30 frames/sec Field of View: Approx. 60 mm X 60 mm t: 0.4 s Seeding: Liquid droplets from TSI 9306 atomizer Processing: Two frame cross correlation Courtesy: NASA - Lewis Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Sonic jet Analysis results from previous slide Shows velocity vectors overlaid on contours of velocity magnitude, contour units in m/s. Courtesy: NASA - Lewis Copyright© 2002 TSI Incorporated

PIV in Supersonic Flow umax ~ 1400 m/sec U - component V- component Supersonic flow umax ~ 1400 m/sec Supersonic flow PIV measurements Courtesy: ISL Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Supersonic Jet Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Flow field behind a car Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Air Flow In a Chamber Air flow in a 62 x 62 cm chamber Region imaged 60 x 60 cm Flow seeded using smoke Flow out Air flow in the flow model is similar to air motion in a room. There is large scale circulating air motion in the chamber. Light sheet in the vertical plane and the cameras are in the horizontal plane. PIV System used (2D Measurements) 120 mJ Dual Mini-YAG lasers with Light Arm with light sheet optics Light sheet height more than 60 cm PIVCAM 10-30 camera Parallel processing (Dual Processor System) Computer-controlled Synchronizer (Model 610034) High speed interface (Model 600067) on-line transfer of data from camera at the highest camera frame rate INSIGHT Data Analysis Package Flow in Copyright© 2002 TSI Incorporated

Air flow - Large Chamber (60 x 60 cm) Magnitude of velocity x- component of velocity Large Scale Flow Pattern Copyright© 2002 TSI Incorporated

PIV Results - Large Chamber Air flow StereoPIV measurements of the same air flow Plot of the w component of velocity normal to the light sheet. w - component of velocity Copyright© 2002 TSI Incorporated

PIV Measurements Tank Water flow Water flow - 35 x 50 cm tank, Region imaged 30 x 30 cm, seeded water flow Water flow is created by flow from a tube mixing with the water in the tank PIV System Dual Mini-YAG lasers with Light Arm with light-sheet optics PIVCAM 10-30 camera Parallel processing (Dual Processor System) Computer-controlled Synchronizer (Model 610034) High speed interface (Model 600067) INSIGHT Data Analysis Package Magnitude of velocity x- component of velocity Copyright© 2002 TSI Incorporated

PIV Measurements 3-component measurements in a channel flow Vorticity W-component Khalitov, Longmire and Anderson (1999) Copyright© 2002 TSI Incorporated

Underwater Flow measurements These systems have Sealed housing for the camera for underwater use. A special light sheet housing for placing the light sheet underwater Underwater Laser Light sheet Underwater Camera Courtesy: INSEAN Copyright© 2002 TSI Incorporated

Water flow behind a propeller Near wake: axial velocity field Measurements in the flow field behind a propeller An experimental investigation of a five-blade propeller wake behind a ship model was performed using Stereo Particle Image Velocimetry (stereo-PIV) in a large free surface cavitation tunnel. Investigation of the wake at different longitudinal stations and its evolution in phase with the propeller pointed out the capability of stereo-PIV in resolving the complexity of the flow field. Phase-averaged results provide a detailed picture of the nature of the flow field. The blade viscous wake, which develops from the blade surface boundary layers, the trailing vortex sheets that are due to the radial gradient of the bound circulation, and the velocity fluctuation distributions were identified. The complex interaction between the hull wake and propeller was described through the evolution of the mean velocity components and the velocity fields. From the 2002 Lisbon Conference paper“Application of Stereo-PIV: Propeller wake analysis in a large circulating water channel” by M. Felli, F. Pereira, G. Calcagno and F. DiFelice. (Courtesy INSEAN-Italian Ship Model Basin) Axial velocity field at x = 0.59R Cross flow at x = 0.59R Courtesy: INSEAN Copyright© 2002 TSI Incorporated

Water flow behind a propeller Wake evolution: Turbulent field X = 0.76 R X = 1.85 R X = 0.59 R Courtesy: INSEAN Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Underwater PIV A StereoPIV system that can be configured to meet the different needs for under water measurements. Copyright© 2002 TSI Incorporated

Copyright© 2002 TSI Incorporated Flowfield in a fan Copyright© 2002 TSI Incorporated

Flowfield in a fan Experimental Arrangement Volute Air flow Laser Camera 1 Camera 2 Copyright© 2002 TSI Incorporated

Flowfield in a fan Results Velocity Vorticity Copyright© 2002 TSI Incorporated

Flowfield in a fan Results vort Strain rate Strain rate vel Copyright© 2002 TSI Incorporated