Variable-rate technologies coupled with broadcast spray systems serve to reduce chemical inputs, misapplication of chemicals, and environmental pollution, thus improving profitability and sustainability. Sprayer variable rate control involves using pulse width modulation (PWM) solenoids and/or direct chemical injection to adjust the application rate. The objectives of this research were to: outfit a conventional broadcast sprayer with PWM and direct inject technologies; evaluate the accuracy of the PWM system to control application rate for strait line and turn segments; and characterize the direct injection system’s transport delay time. For the PWM evaluation, the mean flow rate and coefficient of variation of individual nozzles indicated consistent performance. For the direct injection evaluation, the manufacturer recommended plumbing scheme and injection point location resulted in unsatisfactory delay times, ranging from 105 to 150s for the 8 km h-1 (5 mph) speed and 60 to 90s for the 16 km h-1 (10 mph) speed.

Improvements to heritage gas turbine engines will be needed in the coming years as the demand made on these systems increase. While industry continually presses for higher performance of both military and civilian aero engines, the government simultaneously raises the bar for emissions standards in the commercial sector to support public health. The next generation of aerospace gas turbine engines will be defined by their ability to operate at high power conditions while maintaining efficiency. This challenge is compounded by airlines' proposition of a return to supersonic flight- an operating regime characterized by higher total temperatures, and thus more NOx production. Lean Direct Injection (LDI) is a combustion scheme that was proposed by NASA, and inherently addresses the needs of both the private sector and the military. LDI is a liquid fueled combustor that promotes rapid mixing of fuel and air at the entrance of the combustor. Despite the benefits of LDI, it has never been implemented, nor has any other lean burning scheme been implemented in an aircraft due to the system level complications of such technology. This dissertation focuses on the dynamics of thermoacoustic instability and lean blowout (LBO), two of the major complications that industry will face when they attempt to incorporate LDI in a production engine. The present dissertation investigates these dynamics from a fundamental and applications standpoint. Fundamental insights on thermoacoustic instabilities are developed by investigating droplet dynamics in a self-excited flow field, and significant oscillations in droplet diameters are discerned. PDPA measurement will be taken to identify coupling of the fuel spray with the instability, and a phase locking algorithm will be used to develop a new spray parameter than is more indicative of combustion heat release that the standard Sauter mean diameter. Next, while varying the swirl number and the venturi geometry of the combustor, the evolution of the flow field will be characterized. An in-house innovation called the Direct Rotation Swirler (DRS) is built for this purpose. The DRS uses an active geometry to provide continuously variable swirl number modulation. The effects of these changes on lean blow out, pressure drop and NOx emissions will then be experimentally determined. Venturis were rapidly manufactured using a ii casting procedure that was developed to make venturi geometries from a commercially available ceramic at very low cost. / Doctor of Philosophy / Improvements to heritage gas turbine engines will be needed in the coming years as the demand made on these systems increase. While industry continually presses for higher performance of both military and civilian aero engines, the government simultaneously raises the bar for emissions standards in the commercial sector to support public health. The next generation of aerospace gas turbine engines will be defined by their ability to operate at high power conditions while maintaining efficiency. This challenge in compounded by airlines' proposition of a return to supersonic flight- an operating regime characterized by higher total temperatures, and thus more NOx production. Lean Direct Injection (LDI) is a combustion scheme that was proposed by NASA, and inherently addresses the needs of both the private sector and the military. LDI is a liquid fueled combustor that promotes rapid mixing of fuel and air at the entrance of the combustor. Rapid mixing yields a clean, even flame and eliminates the fuel-rich primary zone which is the heart of NOx production. Despite the benefits of LDI, it has never been implemented, nor has any other lean burning scheme been implemented in an aircraft due to the system level complications of such technology. This dissertation focuses on two of the major complications that industry will face when they attempt to incorporate LDI in a production engine. Drastically reducing the local hot spots in the primary zone is fundamentally necessary to improve pattern factor and emissions, but this change is directly at odds with two dynamic phenomenon that plague combustors. These effects are thermoacoustic instabilities, and lean blow out. Thermoacoustic instabilities are a major concern in any type of combustor and instabilities are more common and more intense in lean engines which is a significant safety risk to aircraft. A thermoacoustic instability occurs when pressure waves in an engine grow to high amplitudes. Small pressure waves are normal in any combustion process, but when the acoustic waves couple with the heat release, the waves can grow uncontrollably. The amplitudes can reach magnitudes capable of damaging the combustor or significantly reducing its cyclic life. Due to the high iv standard of safety in the aerospace industry, lean combustion will not be implemented until engines can be designed to avoid instabilities throughout the entire flight envelope. Lean blow out occurs when the fuel to air ratio of the engine becomes too low to sustain a flame. Lean blow out is a transient phenomenon that is dependent on local flame speeds, local chemical time scales and turbulence parameters. Typically, lean blow out is combated by designing a rich flame anchoring region that burns with plenty of excess fuel so that even if the fuel flow rate is reduced, a core region is still within its flammability regions. The present dissertation investigates these dynamics from a fundamental and applications standpoint. Fundamental insights on thermoacoustic instabilities are developed by investigating droplet dynamics in a self-excited flow field, and significant oscillations in droplet diameters are discerned. PDPA measurement will be taken to identify coupling of the fuel spray with the instability, and a phase locking algorithm will be used to develop a new spray parameter than is more indicative of combustion heat release that the standard Sauter mean diameter. Next, while varying the swirl number and the venturi geometry of the combustor, the evolution of the flow field will be characterized. An in-house innovation called the Direct Rotation Swirler (DRS) is built for this purpose. The DRS uses an active geometry to provide continuously variable swirl number modulation. The effects of these changes on lean blow out, pressure drop and NOx emissions will then be experimentally determined. Venturis were rapidly manufactured using a casting procedure that was developed to make venturi geometries from a commercially available ceramic at very low cost.

As the legislation on vehicle emissions is becoming more and more stringent, increasing attention has been paid to the fine particles emitted by diesel and gasoline vehicles. The high number emission of fine particles has been shown to have a large impact on the atmospheric environment and human health. Researchers have shown that gasoline engines, especially Gasoline Direct Injection (GDI) engines, tend to emit large amounts of small size particles compared to Port Fuel Injection (PFI) gasoline engines and diesel engines fitted with Diesel Particulate Filters (DPFs). As a result, the particle number emissions of GDI engines will be restricted by the EU6 legislation. The particulate emission level of GDI engines means that they would face some challenges in meeting the EU6 requirement. This thesis undertakes research in the following area. Firstly, the filtration efficiencies of glass fibre filters were quantified using a Cambustion Differential Mobility Spectrometer 500 (DMS500) to see if all of the particles from the sampled gas can be collected by the filters. Secondly, various valve timings and different injection modes such as double injection with a second injection after compression, single early injection and split early injection were implemented to measure the Particulate Matter (PM) emissions and combustion characteristics of a GDI engine under warm-up operating conditions. Thirdly, the techniques for removing volatile particles were investigated using a catalytic Volatile Particle Remover (VPR) and an Evaporation Tube (ET) with hot air dilution under various test conditions. The results show that for the glass fibre filters tested here, the transmission efficiencies of the particles are very low, indicating that PM sampling using fibre filters is an effective method of studying the particulate emissions from the engine. Particle number emissions using double injection with injection after compression were much higher than those with single injection during the intake stroke. Under 1200 rpm, 110 Nm cold engine operation, no reduction effect on PM emissions was shown by using split intake injection to further facilitate homogeneous mixture formation compared with single intake injection. Valve timings showed moderate effects on particulate emissions. Properly adjusted timing for exhaust valve closure led to reduced particulate emissions by a factor of about 2 and the combustion characteristics were not adversely affected much. The VPR temperature and exhaust residence time did not show much effect on the catalytic VPR performance once the mass flow rate of exhaust was above 0.09 g/s. Generally, the transmission efficiencies of the VPR follow the trends of the scaled PMP counting efficiency specification. Hot air dilution is effective in reducing the small size particles. At 23 nm, the transmission efficiencies are within the error range of the PMP specification. The catalytic VPR and the Evaporation Tube were all found to be effective in reducing the particle number of small size (nucleation mode) particles. Both systems have some particle loss mainly due to the physical effects of diffusion and thermophoresis. Until now, GDI engines have not been optimised for reducing particulate emissions as the focus has been on gaseous emissions and fuel economy. With careful re-optimisation of the catalyst light-off and engine calibration (especially for transients) then there is scope for GDI engines to meet forthcoming emissions legislation.

The effects of changing nozzle hole patterns and hole geometry in a direct injection natural gas optically accessible engine was investigated. Six nozzles were studied having a 1 hole, 3 hole, and 9 hole pattern; each having either elliptical or circular hole geometries. Combustion images were taken with a high speed camera and the nozzles were compared on the basis of their ignition delay time, rate of heat release, net heat release, fuel utilization, gross indicated thermal efficiency, and particulate emissions. The best performance in all categories was achieved by the 9 hole nozzles which was largely attributed to better fuel mixing as a result of its hole distribution. The elliptical hole geometry exhibited characteristics of improved mixing mainly through reduced ignition delay time and reduced elemental carbon emissions.

The effects of changing nozzle hole patterns and hole geometry in a direct injection natural gas optically accessible engine was investigated. Six nozzles were studied having a 1 hole, 3 hole, and 9 hole pattern; each having either elliptical or circular hole geometries. Combustion images were taken with a high speed camera and the nozzles were compared on the basis of their ignition delay time, rate of heat release, net heat release, fuel utilization, gross indicated thermal efficiency, and particulate emissions. The best performance in all categories was achieved by the 9 hole nozzles which was largely attributed to better fuel mixing as a result of its hole distribution. The elliptical hole geometry exhibited characteristics of improved mixing mainly through reduced ignition delay time and reduced elemental carbon emissions.

The study of single-plume sprays into cross-flowing air is found extensively in literature, however, with the continued development of the Spark Ignition Direct Injection (SIDI) engine, the behaviour of multi-plume sprays in cross-flowing conditions is of interest. In the present work, the injection of a multi-plume spray into a high-velocity cross-flow is investigated; an experimental apparatus capable of providing a cross-flow with core velocities higher than 200 m/s is developed; analysis techniques are developed to characterize the cross-flow and multi-plume spray independently; the multi-plume spray is characterized as it issues into the cross-flowing air. The round air jet used for the cross-flow was designed using the concepts put forth for the design of wind tunnel contractions. The axial and radial velocities were measured using a Particle Image Velocimetry system from LaVision Inc. and the potential core length determined for the core velocities corresponding to Mach numbers of 0.35 and 0.58. It was determined that the potential core length increases with increasing Mach number and that increased compressibility, leads to reduced mixing within the core. Furthermore, velocity profiles of the air jet show that self-similarity is preserved within the shear layer of the initial region. The multi-plume spray was also characterized in quiescent conditions for 10 and 15 MPa injection pressures. It was found that the penetration depth and spray width increased with increasing injection pressure, but that the spray angle decreased with increasing pressure. The increase in penetration depth is consistent with the findings presented in literature, while the decrease in spray angle with increasing pressure is contrary to literature. Next, the multi-plume spray, injected at 10 and 15 MPa, is characterized as it issues into the cross-flowing air stream at Mach numbers equal to 0.35 and 0.58. The tail length and penetration are measured and it is found that for the first, the cross-flow velocity is the primary factor with higher cross-flow velocity resulting in a longer tail length, while for the latter, the injection pressure is the major factor, with higher injection pressures resulting in higher penetrations. That being said, the injection pressure does play a small role in the tail length, with the 15 MPa injection having a slightly longer tail length than the 10 MPa injection in the Mach number 0.58 cross-flow. This is attributed to the finer atomization, which is expected from the 15 MPa injection and which leads to quicker entrainment of fuel droplets into the cross-flow. The spray axis was predicted for each set of conditions from 0.1 ms to 1.0 ms after Start of Fuel (SOF). It was found that before 0.3 ms, the spray retains its multi-plume nature, while after 0.3 ms it behaves like a single-plume spray. Once the spray has crossed this transition point, the spray axis is temporally independent and can be predicted by the logarithmic models, similar to those used for single-plume sprays in cross-flow. The accuracy of this fit is improved upon, with the presentation of a modified correlation, which includes the momentum flux ratio inside of the logarithmic term. Finally, the multi-plume spray issuing into the cross-flow is characterized using PIV to measure droplet velocities. It is observed that the cross-flow momentum is imparted to the smaller droplets within the 15 MPa spray more easily than to those of the 10 MPa injection, but that the 15 MPa sprays also retain their momentum in the radial direction longer than the 10 MPa sprays. As such, the 10 MPa sprays align with the cross-flow axis faster.

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The pig has similar features to the human in aspects such as physiology, immunology, and organ size. Because of these similarities, genetically modified pigs have been generated for xenotransplantation. Also, when using the pig as a model for human diseases (e.g. cystic fibrosis transmembrane conductance regulator), the pig exhibited similar symptoms to those that human patients present. The main goal of this work was to examine the efficacy of direct injection of the CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeats/ CRISPR associated protein 9) in pigs and to overcome shortcomings that resulted after direct injection into the cytoplasm of developing zygotes. By using direct injection of CRISPR/Cas9 into developing zygotes, we successfully generated fetuses and piglets containing 9 different mutations. The total number of aborted fetuses was 20 and of live piglets was 55. Moreover, one issue that was encountered during the production of mutated pigs was that insertion or deletion (indel) mutations did not always introduce a premature stop codon because it did not interfere with the codon read. As a result of these triplet indel(s) mutations, a hypomorphic phenotype was presented; consequently, the mutated gene was partially functional. To prevent this hypomorphic phenotype, we introduced two sgRNAs to generate an intended deletion that would remove a DNA fragment on the genome by causing two double-strand breaks (DSB) during non-homologous end joining (NHEJ). The injection of two sgRNAs successfully generated the intended deletion on the targeted genes in embryos and live piglets. Results after using intended deletions, in IL2RG mutation pigs, did not show hypomorphic phenotypes even when a premature stop codon was not present. After using the intended deletion approach, function of the targeted genes was completely disrupted regardless of the presence or absence of a premature stop codon. Our next aim was to introduce (i.e. knock-in) a portion of exogenous (donor) DNA sequence into a specific locus by utilizing the homology direct repair (HDR) pathway. Because of the cytotoxicity of the linear form of the donor DNA, the concentration of the injected donor DNA was adjusted. After concentration optimization, four different donor DNA fragments targeting four different genes were injected into zygotes. Efficiency of knock-in was an average of 35%. Another donor DNA was used in this study which is IL2RG-IA donor DNA carried 3kb of exogenous cassette. It showed 15.6% of knock-in efficiency. IL2RG-IA Donor DNA injected embryos were transferred into surrogates, and a total of 7 pigs were born from one surrogate, but none of the 7 were positive for the knock-in. Future experiments need to be developed to optimize this approach. Overall, the direct injection of CRISPR/Cas9 is advantageous in cost, time, and efficiency for large animal production and for biomedical research. However, there are still unsolved challenges (off-targeting effects, low efficiency of knock-in, and monoallelic target mutation) that need to be elucidated for future application in humans and other species. / Doctor of Philosophy / The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9) system is commonly used to make genetically modified pigs. The CRISPR/Cas9 system can break the DNA on a desired gene region. During the DNA repair process, random DNA base pairs can be inserted or deleted on the broken regions, thus generating a mutation on the desired gene. Scientists have adopted new methods to disrupt genes in many species. One of these new methods is the direct injection of CRISPR/Cas9 into a fertilized oocyte. In our first project, we used direct injection of the CRISPR/Cas9 system into the fertilized one-cell embryo. A total of 55 live pigs and aborted 20 fetuses with specifically disrupted genes were produced for biomedical research model. During these studies, one critical drawback of the direct injection method was encountered. Partial function of the gene was possible. To prevent this problem, two DNA broken regions were generated by the CRISPR/Cas9 system to remove the middle part the DNA by two DNA breaking. This method successfully removed the middle portion of the DNA targeted region in the pig embryos. Embryos injected with the CRISPR/Cas9 system to cut the two specific DNA regions were transplanted into surrogate pigs, and a total of 15 piglets were produced. All 15 pigs confirmed that a specific part of the gene had been removed by two DNA breakage. Also, no function of the desired gene was found in the 15 pigs. The objective of the last experiment was to introduce a specific exogenous DNA sequences into specific region of DNA using the CRISPR/Cas9 system. For this study, four different exogenous DNA fragments were synthesized for four different genes. When injected, one exogenous DNA along with the CRISPR/Cas9 system, the average integration efficiency of the four exogenous DNA fragments was 35% in the embryo. Another exogenous DNA, which was longer than other four DNA fragments showed 15.6% integration efficiency. The embryos injected with the long exogenous DNA fragment, along with the CRISPR/Cas9 system, were transferred into surrogate pigs. The result was that a total of 7 piglets were born, but the exogenous DNA sequence was not found in none of the seven piglets. In conclusion, the CRISPR/Cas9 system showed effective removal of the entire gene function of specific genes in the pig. However, for future application in the human and other species, some problems (un-wanted region mutation and low efficiency of exogenous DNA integration) continue to emerge and need to be addressed in future experiments.

Increasing concerns over the condition of our environment and its long term health have led to the development of greener combustion techniques for use in turbomachinery applications. Lean Direct Injection is an active area of research for how fuel is introduced and burned in the combustor section of a jet engine or land based liquid fuel turbine. Overall lean combustion results in lower NOx emmisions while direct injection insures shorter combustor lengths. Lean Direct Injection and other lean burning combustor designs are susceptible to thermoacoustic instabilities. The SARA or Synchronously Actuated Response Atomizer is a liquid fuel atomizer and supply system designed to allow for the active control of droplet size, cone angle, and mass flow rate. These three parameters have been shown to be important in controlling combustion quality and heat release. This research investigates the capabilities of the SARA design in a series of non-reacting tests. Static and Dynamic tests were performed on the SARA nozzle with a maximum actuation of 400 Hz. Also, a novel use of hot-film anemometry was developed to measure the dynamic flow rate fluctuations. / Master of Science