This thesis presents an experimental analysis of the effect of temperature and thermal cycles on the performance of PZT ceramics in fuel injector applications. Due to the increase in the implementation of piezoceramics in applications such as fuel injection technology, it is imperative to understand how temperature affects piezoceramic performance. In this project, the fundamental piezoelectric properties (d_33, ε_33^T, s_33^E) of bulk PZT samples and high electric-field properties of piezoelectric stack actuators were obtained with respect to temperature and thermal cycles. The results show that increasing temperature will increase the fundamental piezoelectric properties of bulk piezoceramics, capacitance of stack actuators, and the displacement of piezoactuators in the absence of external load. Raising the temperature while applying a constant preload will initially increase piezoactuator displacement, but decrease it at higher temperatures. Temperature had a negative effect on the hysteresis in the displacement-voltage. Additionally, thermal hysteresis decreased significantly in subsequent temperature cycles.

Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial’s properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires’ electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.

A mathematically consistent algorithm for simulating interfacial turbulent flows is devised in this work. To minimize numerical errors for imposing dynamic boundary conditions at the interface locations, piezometric pressure is used to limit the effect of gravity forces in a flow field. Consequently, suitable and consistent numerical schemes are designed to accurately implement the new forms of interfacial forces. The proposed numerical methods are challenged for low Froude number flows which tend to trouble conventional algorithms. To capture the effect of turbulence on the interface, standard large eddy simulation techniques are reviewed and discussed. It is shown the standard filtered flow equations encounter numerical and mathematical inconsistencies. To remedy the irregularities of the conventional methods, a new framework for large eddy simulations is grounded. Purely mathematical models are derived and correlated with the conventionally more physical models. Semi implicit SIMPLE method is used to discretize the final flow equations. Taking advantage of the implicit feature of SIMPLE algorithm, an error correction technique is devised by which numerical cost of a turbulent simulation is substantially reduced. The entire framework is finally discussed toward simulating a turbulent interfacial flow.

The physical mechanism responsible for droplet manipulation in electrowetting on dielectric (EWOD) devices is not yet fully understood. This investigation will examine the role of capillary forces on droplet manipulation to further the physical understanding of these devices. An analytical model for the capillary force acting on a confined droplet at equilibrium is developed here. Model predictions were validated using optical measurements of the droplet interface in the vertical plane. It was found that the capillary force and interface shape predicted by the equilibrium model were over an order of magnitude more accurate than predictions from the model commonly used in EWOD investigations. The equilibrium model was adapted to droplets with arbitrary shapes to predict droplet dynamics in EWOD devices. It was found that droplet motion could be described using the driving capillary force and frictional forces from wall shear, the contact line, and contact angle hysteresis. Comparison with experimental data shows that this model accurately predicts the effects of applied voltage and droplet aspect ratio on the transient position and velocity of droplets. This model can be used to design EWOD devices and predict the simultaneous manipulation of droplets required to meet the high throughput demands of practical applications. A robust system for droplet monitoring must be automated before EWOD devices can be used reliably in practical applications. Although capacitance measurements have been used to automate droplet detection in EWOD devices, manual optical measurements are generally used to monitor droplet mixing. This may not be possible in high throughput applications with multiple droplets and limited optical access. Here, capacitance measurements are shown to be an accurate and repeatable means of monitoring droplet composition and real time mixing. Experiments were performed with this technique to show that mixing efficiency is better characterized by the number of translations required for full mixing, not mixing time.

A pneumatic droplet generator is described, which consists of a T-junction with a nozzle fit into one opening, the second opening is connected to a gas cylinder through a solenoid valve and the third connected to a length of steel tubing. The droplet generator is filled with liquid. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the gas above the surface of the liquid. A jet of liquid issues far enough out of the nozzle that its tip becomes unstable, detaches and forms a droplet. Experiments were conducted using water/glycerin mixtures and molten metals including tin, zinc and zinc alloy. Droplet formation was photographed and the pressure variation inside the droplet generator recorded. The effect of various experimental parameters such as nozzle size, pressure pulse width, secondary gas flow pressure, liquid viscosity and temperature on droplet formation were investigated. An analytic model of incompressible liquid motion in the nozzle is used to explain the behavior of water/glycerin solutions inside the nozzle and droplet formation. The model demonstrates that the motion of the surface is out of phase with the exciting pressure oscillation. Experiments showed the oscillation of the liquid surface prior to droplet ejection and the time lag between the pressure oscillation and droplet ejection. The model predicts that maximum liquid velocity is attained at an intermediate value of viscosity, and experiments confirmed that the largest liquid motion was achieved with this intermediate value, which eventually leads to droplet formation. Similarly, with molten metals, a simple analytical method was used to estimate the diameter of droplets. The size of tin droplets measured from experiments was in good agreement with that obtained from the model.

Dusting is one of the major problems in the operation of lime kilns because dust particles interfere with kiln operation and reduce its efficiency. A numerical model is developed to predict the rate of dust formation in rotary lime kilns. The model consists of four major components: 1) a 3D model for the kiln gas, solving fluid flow, heat transfer, and combustion in the gas region; 2) a 1D model for the kiln bed, solving for variation of the solids composition, including moisture content, along the kiln; 3) a 3D model to predict the motion of the solids in the bed, and to estimate the reaction rates; 4) a mathematical model to predict the rate of particle pickup from the bed. Additionally, motion of dust particles was modeled, for the first time, using Stochastic Separated Flow model (a Lagrangian approach). The developed model of particle tracking enables the user to predict distribution of dust particles in the gas section of the kiln. Different components of the model were validated using experimental data published in the literature. The developed model was used to simulate operation of a full-scale lime kiln at typical operating conditions, i.e. at different fuel and air flow-rates. Dusting signatures were also estimated for each setting to determine the effect each operating condition has on dusting. The results presented in this thesis indicate that dust formation is mainly affected by the kiln gas velocity. Effect of other operating conditions was found to be negligible within the ranges studied. The results presented here suggest that dust formation can be controlled by minimizing the input gas flow rate.

The fouling of heat transfer surfaces in kraft recovery boilers is a significant concern for the pulp and paper industry. The usual approach to controlling fouling is the use of so-called ``sootblowers,'' that utilize boiler steam to generate supersonic steam jets that are literally used to knock deposits off of the boiler tubes. About 3 to 10\% of the total steam produced in a recovery boiler is used for sootblowing. This high energy cost demands that they be operated as efficiently as possible. It is thus essential to devise improved strategies for maximizing sootblower efficiency and minimizing steam consumption. To achieve this, the behaviour of sootblower jets, and the effects of various parameters on sootblowing, must be well understood. This thesis documents a study of the performance of sootblower jets using numerical simulation; CFDLib 3.02, a CFD code from the Los Alamos National Laboratory, was used for the simulations. This work had two main parts. In the first part, sootblower jets that perform at the design condition (fully-expanded jets) were studied; in the second part, the study was extended to off-design (under/over-expanded) sootblower jets. In the first part, a compressibility-corrected version of CFDLib was validated against a wide range of available experimental data, of subsonic and fully-expanded supersonic free and impinging jets; simulations successfully predicted all of the cases. This compressibility-corrected model was then deemed suitable for modeling the fluid mechanics of fully-expanded sootblower jets, and so was used to study the effects of two parameters on sootblower jets: the lance pressure, and the rate of rotation of a sootblower. To study the effect of the lance pressure, numerical simulation was used to model fully-expanded sootblower jets corresponding to a range of lance pressures. To study the effect of rotation, the equations of motion were modified by adding the Coriolis and centrifugal terms, so that computations could be performed in a rotating frame of reference. Simulations were then run to study a fully-expanded sootblower jet operating at different rotation rates. The results indicate that sootblowers operate more efficiently at lower lance pressures, and that the rate of rotation does not significantly affect the structure of a sootblower jet. In the second part, the study was extended to sootblower jets not operating at the design condition. The compressibility-corrected code failed to properly simulate these under-over/expanded supersonic jets. A wide series of tests was carried out to determine that the problem was due to the turbulence model. The model was then modified to account for turbulence/shock wave interaction, by adding corrections to take into account shock unsteadiness and a realizability constraint. The new model yielded good agreement with some available measurements. The new model was then used to successfully predict some actual sootblower measurements, and to study the interaction of a sootblower jet with geometries similar to tube banks in recovery boilers. A parametric study was carried out to examine the effect of the offset between a sootblower jet and a tube bank, and of deposit size on a sootblower jet. The results indicate that the shock cell structure of a jet is only slightly affected by the offset, but that the size of a deposit strongly affects the pressure exerted by the impinging sootblower jet, which depends both on the jet shock cell structure, and on the location where the interaction occurs.

Physical pick-and-place promises specificity, precision, and programmed motion, a feature making microrobotic manipulation amenable to automation for the construction of microsystems. Despite the significant progress made, a long-standing difficulty is the release of micro objects from the end effector due to strong adhesion forces at the micro scale. This research focuses on the development of microelectromechanical systems (MEMS) based microgrippers that integrate an active release mechanism for pick-and-release micromanipulation. The performance was experimentally quantified through the manipulation of 7.5-10.9µm glass spheres, and for the first time, achieves a 100% success rate in release (based on 700 trials) and a release accuracy of 0.45±0.24µm. Example patterns were then constructed through automated microrobotic pick-and-place of microspheres, achieving a speed of 6sec/sphere. To further miniaturize the devices for nanomanipulation, a novel fabrication process was developed. Through the manipulation of 100nm gold nano-particles inside a scanning electron microscope (SEM), preliminary demonstrations were made.

This thesis focuses on the development of a novel hybrid linear actuator (HLA). The research includes the optimal design, the particular fabrication, and the experimental validation. The principle of the HLA is based on the integration of the mechanisms of the solenoid actuator and the voice coil actuator. Such integration is achieved by a magnetic circuit consisting of a magnetic flux orientator, a permanent magnet, a composite shell, and a special coil. The HLA is capable of having a high repelling force at one end and a high attractive force at another end. A step-optimization technique is developed and used to determine the key parameters of the HLA, with the aid of sweeping functions in finite element analysis. Moreover, a single-pulse power supply is specially designed and prototyped for driving the HLA. The performance of the HLA is systematically characterized by simulations and experiments.

A series of steady-state water condensation experiments were conducted to determine the effects of Marangoni convection on the condensation flux. The interface was flat so that the results of the interfacial temperature discontinuities could be compared to past condensation experiments conducted under similar experimental conditions using a spherical interface. Two experimental methods were used. Method 1 was to vary the temperature in the cooling pipes (Tcp ) with the position of the interface relative to the cooling pipes fixed. Method 2 was to vary the position of the interface while Tcp was held constant. The interfacial temperature discontinuities in this study were approximately 2.3-9 times smaller in magnitude, than those measured using a spherical liquid-vapour interface. The experimental results showed that the condensation flux increased as thermocapillary convection increased (increase in interfacial temperature gradients and speed). This increase resulted in a 1.37-12.5 times enhancement in the condensation flux of pure water.