Many fuel spray characterization studies to date have been conducted in quiescent environments with single-hole fuel injectors. However, in actuality, multi-hole injectors spray into direct injection engine cylinders where significant air swirling and tumbling exist to promote fuel atomization and air-fuel mixing, which result in more efficient combustion. For this reason, researchers have begun developing correlations for fuel sprays where a jet of air acts perpendicularly to the fuel spray, also known as a cross airflow or crossflow, so as to more realistically predict fuel spray characteristics in direct injection engines. Accordingly, there is a need for a foundation of experimental data reflecting the specific conditions of fuel spray in cross airflow which can then be used for model validation and future engine design and development. In this study, fuel sprays are characterized with a commercial 8-hole fuel injector in a wind tunnel enclosure capable of cross airflows upwards of 200m/s. Particle image velocimetry was used to measure air velocities and capture pulsed spray events of biodiesel, diesel, and biodiesel-diesel blend fuels. Spray images were processed and analyzed in LaVision's DaVis and in MATLAB to calculate spray penetration length and axis deflection angle under varying cross airflow velocities, fuel injection pressures, and fuel types. Results show that strong cross airflows can decrease spray penetration by up to 44% and deflect the spray axis by up to 10.5° when compared to the same spray in a quiescent environment. Additional experiments reveal that biodiesel experiences slower spray progression when compared with diesel, resulting in shorter spray penetrations in the early phase of the spray development (up to 0.7ms after the start of injection, or ASOI). The angle between the fuel injector axis and the air jet axis plays an important role in determining the resultant spray characteristics. This angle should be considered in future correlations.

With widespread use of pesticides in modern agriculture, the impacts of spray drift have become a topic of considerable interest. The drifting of sprays is a highly complex process influenced by many factors. Advances in aerial application technology and in our ability to measure drift, coupled with the adoption of new technologies for regulating pesticide application have necessitated further research in the pesticide application process. Experiments were conducted to quantify spray drift and describe its movement from aerial applications of pesticide. The effects of spray quality, atomizer type and ground cover were examined. Initial airborne drift amounts were greater than downwind deposits, thus not all of the drifting spray was deposited in the measuring area. Total off-target movement of spray was significantly greater for Fine compared to Coarse sprays. Rotary and hydraulic atomizers, both producing Fine sprays, produced statistically similar off-target movement of sprays. Similarly, no significant statistical differences in spray drift between applications to bare ground and applications to a headed barley crop canopy were not identified. Contrary to expectations, aerial application to bare ground seemed to result in less off-target movement than application to a crop canopy. The vertical spray cloud profiles were similar for all applications with the greatest amount of spray present at the height of release. Spray concentrations diminished from that height upward with diffusion and downward with deposition. The empirical data disagreed with the mechanistic model AgDISP which is currently used in the Canadian regulatory process. The model over-predicted drift deposition by a factor of two to five. Variability in spray deposit values could not be attributed to average differences in meteorological conditions at the time of application. Experiments with appropriate protocols for increased sensitivity may be required to more accurately report subtle differences in drift at distances greater than 200 m from the target area.

Pesticide use is an important component of the agricultural industry. Pesticides are typically applied to crops as a droplet spray, and these droplets are susceptible to off-target movement due to wind, which is called spray drift. It has recently been recognized that shelterbelts may protect vulnerable downwind areas from spray drift. There is a need to characterize the movement of spray drift past a shelterbelt to better understand the extent of this protection and the variables which affect it. The variables investigated in this research may be classified as meteorological conditions, spray application settings, and shelterbelt properties.<p>This research investigated the movement of spray drift past a 5 m tall carragana/chokecherry shelterbelt. Spray was applied using a conventional sprayer that travelled on a path that was upwind and parallel to the shelterbelt. A tracer substance was mixed into the spray solution, and the deposition and airborne concentration of drift was measured using a variety of collectors placed at perpendicular distances up- and downwind of a shelterbelt. The mass of drift deposit on the collectors was determined using spectrofluoremetry and standard solutions.<p>When the spray swath was a distance of 3H (where H is the height of the shelterbelt) upwind of the shelterbelt, it was found that the ground deposition of drift at a distance of 0.5H downwind of the shelterbelt was reduced by approximately 74%, compared to the drift deposit at 0.5H upwind. The reduction over the same downwind distances was 29% in the open field setting. The airborne drift cloud was attenuated by the shelterbelt and the airborne concentration of drift exiting the shelterbelt was reduced by approximately 85% of the entering drift. The airborne drift concentration profile indicated that there was a greater proportion of drift travelling over the top of the shelterbelt rather than passing through the shelterbelt, with the peak concentration occurring at approximately 1.2H.<p>Qualitative and multiple linear regression analyses were used to determine the significance of a number of meteorological and controlled variables on the deposition of drift. It was found that the mass of drift deposited downwind of the shelterbelt increased with a higher wind speed, higher temperature, and lower relative humidity. For the range of meteorological conditions sampled, the effect of wind direction and atmospheric stability were found to be insignificant. Finer spray qualities and higher shelterbelt optical porosity produced greater airborne drift and deposition downwind of the shelterbelt. With increasing upwind sprayer distance, the mass of drift deposited within the shelterbelt decreased.

To adhere to the current requirements for NOx and CO emissions in combustion systems, modern land and air based gas turbine engines often operate in the fuel lean regime. While operating near the lean blow out (LBO) limit does reduce some harmful emissions, combustor stability is sacrificed and extinction becomes a major concern. To fully understand the characteristics of lean operation, an experimental study was conducted to map the time averaged flow field in a typical industrial, counter-swirling, liquid fuel combustor. This study examined two steady-state operating conditions, both near the lean extinction limit for this swirl burner. Using an LDV/PDPA system, 2-D mean and fluctuating velocities, as well as Reynolds stresses, were measured throughout the combustor. These measurements were taken for both the non-reacting and reacting flow fields, enabling a direct analysis of the result of heat addition and increased load on a turbulent swirling flow field. To further understand the overall flow field, liquid droplet diameter measurements were taken to determine the fuel spray characteristics as a function of operating pressure and rated spray angle. Chemical composition at the combustor exit was also measured, with an emphasis on the concentrations of both CO and NOx emissions. This large database of aerodynamic and droplet measurements improves understanding of the swirling, reacting flow field and aids in the accurate prediction of lean blow-out events. With this understanding of the lean blow-out limit, increased fuel efficiency and decreased pollutant emissions can be achieved in industrial combustors, especially those used for thrust in the airline industry.

Improving the efficiency of a Pre- Rinse Spray Valve (PRSV) is one of the most cost effective water conservation methods in the Food Services Industry. A significant contributor to this cost efficiency is the reduction in the energy costs required to provide the mandatory hot water. This research paper estimates the potential quantity and dollar value of the water and energy that can be saved annually in Texas A&M University's dining services with the installation of low flow pre-rinse spray valves. The data collection was obtained from four of Texas A&M University's Dining Services facilities. The annual savings were estimated by contrasting the water consumption of the existing T & S Brass B 0107-M PRSVs with the latest and most advanced available low flow T and S Brass B 0107-C PRSV. The annual water consumption of the existing and new PRSVs were predicted by measuring an individual average flow rate for each and observing the number of hours per day the PRSV would be used. The observed and measured values were extrapolated to amount rates to determine cost savings. The dollar value was ascertained using the utility cost data recorded over a semester by the Facilities Coordinator of the Department of Dining Services. The findings of this study show that the water savings from a single PRSV could lead to an estimated annual saving ranging between 46% and 78% of the current operation cost. The T & S Brass B 0107-C PRSV is currently priced between $52- $60 per valve resulting in a payback period ranging between 1.5-6 months per valve. If every valve on campus was replaced, the University could reap a savings in the range of $ 5,400- $22,590 over the 5 year useful life of the valve, having initially invested less than $550.

Spray cooling is one of the most promising technologies in applications which require large heat removal capacity in very small areas. Previous experimental studies have suggested that one of the main mechanisms of heat removal in spray cooling is forced convection with strong mixing due to droplet impingement. These mechanisms have not been completely understood mainly due to the large number of physical variables, and the inability to modulate and control variables such as droplet frequency and droplet size. Our approach consists of minimizing the number of experimental variables by controlling variables such as droplet direction, velocity and diameter. A study of heat transfer for single and multiple droplet impingements using HFE- 7100 as the cooling fluid under constant heat flux conditions is presented. Monosized single and multiple droplet trains were produced using a piezoelectric droplet generator with the ability to adjust droplet frequency, diameter, velocity, and spacing between adjacent droplets. In this study, heaters consisting of a layer of Indium Tin Oxide (ITO) as heating element, and ZnSe substrates were used. Surface temperature at the liquid-solid interface was measured using Infrared Thermography. Heat transfer behavior was characterized and critical heat flux was measured. Film thickness was measured using a non-invasive optical technique inside the crown formation produced by the impinging droplets. Hydrodynamic phenomena at the droplet impact zone was studied using high speed imaging. Impact regimes of the impinging droplets were identified, and their effect on heat transfer performance were discussed. The results and effects of droplet frequency, droplet diameter, droplet velocity, and fluid flow rate on heat flux behavior, critical heat flux, and film morphology were elucidated. The study showed that forced heat convection is the main heat transfer mechanism inside the crown formation formed by droplet impingement and impact regimes play an important role on heat transfer behavior. In addition, this study found that spacing among adjacent droplets is the most important factor for multiple droplet stream heat transfer behavior. The knowledge generated through the study provides tools and know-how necessary for the design and development of enhanced spray cooling systems.

An experimental investigation was carried out to examine the jet impingement and spray cooling. There are three parts in this study. The first part was investigated the effects of jet impinging positions on heat transfer from rib-roughened (square and semi-circular) channels with rotational speeds of up to 600 rpm. Results were presented for rotating number (Ro), jet impinging position, surface roughness and jet Reynolds number effects on local Nusselt numbers. The second part was studied instantaneous velocity fields for a single slot liquid microjet using MPIV. The streamwise mean velocity fields and flow evolutions with six nozzle-to-target spacing ratios of 0.86, 1, 1.2, 1.5, 2 and 3 and for eight jet Reynolds numbers Re of 50, 100, 150, 200, 250, 300, 350 and 400 were measured and calculated. The third part was investigated the flow field and heat transfer mechanism for water spray and cryogen (R-134a) spray cooling. An optical image system was used to quantify the droplet size and distribution and Laser Doppler Velocimetry (LDV) measurements to obtain the local velocity distributions. The effects of mass flow rate and average droplet velocity, and spray exit-to-target distance on the surface heat flux including the corresponding critical heat flux (CHF) were explored for R-134a which may enhance the current cryogen spray cooling (CSC) technique that assists laser therapy of dermatoses.

Abstract Spray cooling is frequently encountered in a number of engineering applications. An experimental study was made to investigate the effect of liquid sprays used to cool a hot surface. Both pure water and R-134a were served as a working medium sprayed from a single circular nozzle onto a Pt plated surface of an electrically heated surface. Spray cooling tests were performed for steady state and transient experiment. Cooling characteristics curves were obtained over a range of Weber number(Water¡G80¡B148¡B231¡AR-134a¡G50¡B96¡B152),pressure drop of liquid(0.1Mpa¡B0.15Mpa¡B0.2Mpa),degree of subcooling (Water¡G55¢J¡B60¢J¡AR-134a¡G2¢J¡B4¢J) and initial temperature(Water¡G240¢J¡AR-134a¡G60¢J). Thermal design data of high performance as well as more and further physical insight of the above-stated spray cooling heat transfer can be acquired. The results will hopefully be helpful not only for the academia but for the industry.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "January 2009." Includes bibliographical references (p. 215-236). Also available via the World Wide Web.

The immobilization of antibodies on silica surfaces has been a wide and common practice via cross-linking with the formation of covalent bonds between surface and antibody. The formation of antibody thin films on solid surfaces using pneumatic spray (PS) as the deposition technique and the analysis of the surface morphology of these films were investigated during this study. The pneumatic spray method was compared with the covalent bonding method Avidin-Biotin Bridge (ABB). The intensities and capture efficiency tests showed similar results for both techniques with a lower signal-to-noise ratio (SNR) for the PS deposited films. Specificity tests suggested that the bio-sensitivity of the antibody films that were pneumatically sprayed maintained their capture abilities after the immobilization process. Analysis obtained from the attenuated total reflectance Fourier transform infrared ATR-FTIR support these results indicating that the antibodies retained their native structure and chemical stability thorough the induced physisorption process. The pneumatic spray films also preserve mechanical stability by adhering to the surface after the rinsing procedures. Capture efficiency was tested for both immobilization techniques, the results of which were similar. The pneumatic spray technique was also tested using a diverse range of deposition times. It was shown that a 2 minute deposition time was sufficient to produce a film with similar capture efficiency to the avidin-biotin bridge technique. The surface density obtained for the 2 minute deposition was 9.05 ng/mm2, which is higher than the range of 2.2 to 4.74 ng/mm2 reported for the avidin-biotin bridge technique[1-3]. The contact angle measurements for the pneumatic spray films showed a higher hydrophobicity compared with the avidin-biotin bridge films. This is due to the higher surface roughness obtained for the avidin-biotin bridge films, a higher surface density for the PS and the random orientation of the antibodies in the pneumatic spray films. A study of shelf life showed that the pneumatic spray technique produces stable films that can be used for as long 100 days (study performed only up to 100 days) with similar capture efficiency to those prepared in the same day. To further understand the improvement in capture efficiency of the pneumatic spray films, the surface morphology was investigated to determine its influence in the cell adhesion process. The surface was characterized by several different techniques: ellipsometry to determine the thickness of the films, atomic force microscopy (AFM) to calculate the surface roughness, optical microscopy to identify particle formation during antibody immobilization process, fluorescent microscopy and sandwich fluorescent immunoassay to observe the immobilization patterns of antibodies and antigens on the surface, contact angle measurements to analyze the wettability of the antibody films and X-ray photoelectron spectroscopy (XPS) to confirm the presence of antibody on both deposition methods and to propose a growth model for the pneumatic spray deposition technique. A possible explanation for the similar results of capture efficiency for both techniques can be attributed to three main factors. First, the antibodies retained their native structure thorough the induced physisorption process allowing then to capture antigen normally. Second, the lack of orientation of the antibodies in the pneumatic films was compensated by high surface density thereby offering more binding sites to capture antigens. Third, hydrophobic surfaces are favorable to cell adhesion, therefore the high hydrophobicity of the pneumatic spray films increases the capture efficiency. It is important to mention that the time that it takes to produce the immunoassay surfaces was reduced dramatically from more than twenty four hours for the avidin-biotin bridge films to only a few minutes for the pneumatic spray films. In addition, pneumatic spray films significantly reduce the amount of materials and chemicals used in the deposition process. These factors make the pneumatic spray technique an excellent technique for the immobilization of antibodies on glass slides for commercial bio-sensor devices.