Particle Image Velocimetry (PIV), Planar Laser Induced Fluorescence (PLIF)
Particle Image Velocimetry and Planar Laser Induced Florescence are non intrusive methods for quantitative measurements of fluid flow. In PIV, movement of tracer particles being carried by a fluid is used as a means to observe velocity field. Another similar method incorporates different types of dye to give a measurement of scalar field using almost the same equipment. This method is called PLIF and can be used to measure different fluid phases, varying temperature, or different species in reaction. Both methods use laser optics and image processing. We are working with Nd:YAG laser for PIV and passive scalar PLIF, and dye laser for temperature PLIF along with reactive PLIF. Different kinds of fluorescent dyes are incorporated for each method.
The above image is really cool, but you need red/blue 3D goggles to see what it shows. Open the actual image and there, the red dots are the particles in the first frame and blue dots are the particles in the second frame. That movement of particles you can see alternating between red and blue. The white arrows then show the velocity calculated based on that movement of particles. Scan through the image to see different directions and magnitudes of velocity in different regions. It is worth mentioning that it is a real image I took for the case of a single sphere in flow.
Prof. Olsen has worked with founders of these methods and throughout past years, his research group have developed the knowledge and expertise to carry out a broad range of experiments using methods related to PIV.
Fluidized bed reactors have application in catalytic reactions for different types of plants in different petroleum and biologic industries. We are trying to use simultaneous PIV/PlIF to quantitatively measure flow and temperature fields in such a reactor. My experiment involves liquid-solid two phase flow that incorporates the technique of matching index of refraction of fluid and particles. This enables us to visually access the inside of the reactor without interrupting its behavior.
This is the main project I have been working on. I started with designing this facility based on the proposal and then manufacturing and assembly of it as the next step. The last step was to get the instrumentation for data collection and process to work. I finally started collecting data for the regular 2C velocity field, 3C velocity field, and finally the exciting simultaneous SPIV/PLIF. Based on the preliminary results, we could identify a serious problem with our method. It was quite discouraging to find out that the type of data resulting from the experimental method is in its nature different from the simulation results.
The upside of the current situation is that now, I am building the concept of experiment by myself rather than just performing some tests. The new design will allow me to collect data in a real fluidized bed rather than the current fixed particle scheme. I am focusing on sedimentation as a starting point and I will be working to get 3D particle tracking data in the new facility. Stay tuned!
Flow of a fluid between rotating cylinders is called a Taylor-Couette flow. This type of reactor is being used in algae growth application in our labs in which air as a second phase fluid is injected from the bottom of the reactor containing water and algae. We are setting out to gather precise data of bubble shape and transport in such a flow regime. The idea is to use two immiscible fluids with the same index of refraction inside a reactor so that we can prevent distortion of laser sheet and image due to the bubble shape. a fluorescence dye in the bubbling phase would enable us to use PLIF for distinguishing the two phases.
Multi Inlet Vortex Mixer
In production of nano particles, certain conditions need to be maintained for a reaction in order to keep the products within the required size. This would generally be achieved by a relatively fast mixing of reactants and swift purge of product to prevent agglomeration for the most part. Our research group has already done different experiment with a micro MIVM in the past. In a pursuit of scaling up the facilities for larger amount of production, we are extending our knowledge by developing a macro MIVM using the same concepts. We will investigate fluid flow and reaction using SPIV and Reactive PLIF in this reactor.
Simulation of a Diesel engine combustion merely is a matter of simulating fuel sprays in the cylinder. As the MSc final project I developed a multi-zone spray simulation which is used for 1-D numerical engine model. Such models are used for overall engine performance investigations. Later, my PhD adviser, Ali Salavatizadeh, incorporated a soot formation model in that code.
Free and Forced Convection Heat Transfer
My BSc project was in collaboration with Mohammad Mazaheri who is one my best friends. Most of the credit of it goes to him, but our project turned to be chosen as the best in Iranian Society for Mechanical Engineers (ISME). We experimentally investigated convection Heat transfer of air in eccentric annulus.
I am not necessarily a fan of numerical simulation, but I have a knowledge of CFD through being involved in different research projects.