Turbulent jet flows are very common in engineering applications. One example is that of fuel injection in internal combustion engines, which is closely related to the combustion process. Because of the widespread use, the resulting emissions of such engines have a significant impact on human health and the environment. For a long time, research has sought to improve the mixing in developing turbulent jets to reduce the level of pollutants. Findings have indicated that injection unsteadiness can be used to improve the spray quality. Furthermore, it has been demonstrated that important spray characteristics can be linked to physical phenomena occurring in the region close to the nozzle. In this work, the breakup of an intermittently injected jet is investigated using numerical simulations. Cases of both single-phase and two-phase conditions are studied, characterizing the pulse breakup for different injection timing and varying fluid properties. For single-phase pulsation, mixing efficiency is shown to be connected to the generation of different secondary flow structures and their interaction. The breaking of symmetry along the pulse, responsible for the increased the mixing, is explained through a consideration of vorticity transport. This sequence shows local mixing is faster in the trailing region of pulses that are long enough to form secondary vorticies in the corresponding region. The study is extended to include effects of acceleration and deceleration during injection. The mixing rate depends on the accumulation of jet fluid within the generated flow structures. A rapid injection increase or decrease is found to promote the jet mixing and spreading by triggering jet fluid shedding and destabilization of such flow structures closer to the nozzle. Slow velocity changes promote separation of the injected fluid which instead suppresses near-nozzle mixing. Simulations of intermittent injection of liquid into quiescent gas have also been performed. Primary breakup of liquid pulses is assessed by considering the increase of the liquid-to-gas interface area and volumetric decrease over time. The disintegration process for these cases are less sensitive to the surrounding gas flow because of the higher jet inertia. Increased injection frequency and lower injection to non-injection ratio, is observed to stimulate primary breakup. This is due partly to a stretching action near the nozzle, and partly to a stronger relative influence of collision between liquid pulses. / <p>QC 20160504</p>

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Thesis--Göttingen. / In Periodical Room.

The "Water-Blow" Pulsation generator has been used to produce pulsing fluid flow in an off-the-shelf industrial single pass heat exchanger containing 5/8 in. 0. D. tubes, 37 inches long. Experimental results showed that heat transfer from steam to flowing water could be enhanced by as much as 100%, although a more practical enhancement would likely be about 40%. From the experimental results it was estimated that pulsing air requirement (standard cu. ft. air per cu. ft. water) increased linearly from about 0 to 4.0 over a range of heat transfer enhancement from 0 to 40%. Two factors which influenced pulsing air requirement were the air surge volume sizes and the pressure fluctuations which occurred therein. / Thesis / Master of Engineering (ME)

This thesis has analysed spectroscopic data for three stars in detail, the β Cephei star V2052 Ophiuchus, the γ Doradus star QW Puppis and the γ Doradus candidate star HD139095. Twelve other candidate γ Doradus stars have had their Vrotsin i, binary status and, where possible, the presence of line profile variation determined. A new technique utilising scaled delta functions has been developed to allow the extraction of a single, high S/N line profile from a high resolution and large wavelength range spectrum. This procedure has performed well in the γ Doradus stars examined. The application of the new mode identification technique, the Fourier Parameter Fit method, to the three stars examined in detail has been very successful. For each of the three stars constraints have been placed on the degree (l) and the azimuthal order (m) of the non-radial pulsation modes detected.

This thesis has analysed spectroscopic data for three stars in detail, the β Cephei star V2052 Ophiuchus, the γ Doradus star QW Puppis and the γ Doradus candidate star HD139095. Twelve other candidate γ Doradus stars have had their Vrotsin i, binary status and, where possible, the presence of line profile variation determined. A new technique utilising scaled delta functions has been developed to allow the extraction of a single, high S/N line profile from a high resolution and large wavelength range spectrum. This procedure has performed well in the γ Doradus stars examined. The application of the new mode identification technique, the Fourier Parameter Fit method, to the three stars examined in detail has been very successful. For each of the three stars constraints have been placed on the degree (l) and the azimuthal order (m) of the non-radial pulsation modes detected.

[ Abstract ] This research is for the purpose of to Kaoshiung south funds of utilization and the development tendency the area someone public industry high-level vocational school, makes the partial analyses and the research. The discussion affects this school funds budget disposition factor with whether has the decision-making by chance and of relativity utilization of and the social pulsation the funds. Disposition of in view of the education funds and effectiveness proposed the research suggestion, will be advantageous to future establishes reference the long-term education resources plan as the school, the display education resources effectiveness maximization. Front in order to achieve states the goal and studies budget, the final accounts material the school using the Kaoshiung municipal government, with same economic activity target and so on time economical growth rate, each kind of stock price index, labor productivity index, using the number of times percentage analysis, the mean value and the standard difference analysis, to examine and statistical method analysis and multiple regression analysis tests each hypothesis. Specifically says below, this research obtains the conclusion: (1) School frequently disburses the funds influence factor, from to the student counts for guides carries on the plan funds, this research real diagnosis demonstrated has the high relativity for to reveal the factor with the literature research discussion conclusion is consistent, but the Kaoshiung municipal government frequently budgets also for reveals the factor, obviously the public school frequently disburses mainly admires the municipal government to allocate funds to take from a surplus to supply an insufficiency, frequently disburses take the student counts as the guidance, carries on frequently disburses the plan pattern, basically is the direction which the present stage should maintain. (2) Capital funds counts take the student as the explanation variable, is possible in this research institute supposition to affect in the variable to demonstrate school of capital outlay investment the research changes certain part and the student number presents the reverse relations. (3) The capital outlay makes the analysis by the detail material, the information branch and the information equipment funds possibly explains the variable, has the student to count, the electronic stock price index all for reveals the negative direction explanation factor. (4) Is possible by the school total funds analysis to affect the variable, for reveals with the teaching and administrative staff number to, change influence possible factor and the teaching and administrative staff number the total funds have to the relativity, but the student number reveals the negative direction change, has the difference with the universal cognition, after or is most mainly included the capital outlay the total funds, causes the student to count this variable to make the regression analysis to the total funds to present reverse reveals the influence. (5) The student counts the growth, with the labor production index, the economical growth index changes the movement explanation variable, finally demonstrated the student counts the change, in certain degrees by the labor production index, the economical growth index is possibly changed two factors to explain. (6) Practice equipment budget various branches capital disbursement, studied the school still to have the many branches other student to practice the equipment unit cost to reveal is outdoing other branches, discovered possibly had the decision-making in this aspect school by chance.

In der Hydraulikindustrie gibt es einen großen Bedarf, mit einer einfachen Methode Volumenstrompulsationen messen zu können. Diese Arbeit beinhaltet die Entwicklung einer neuen Technik, die auf Differenzdruckmessung zwischen zwei Punkten der instationären Strömung basiert. Um die dynamische Antwort des Sensors zu bestimmen, wurde der Zusammenhang zwischen Volumenstrompulsation und Druckdifferenz bestimmt. Die niedrige Eigenfrequenz der vorherigen Sensorversionen wurde mit Hilfe eines optischen Druckwandlers erhöht. Dieser Wandler wurde zu diesem besonderen Zweck adaptiert, einschließlich die Analyse der reflektierenden Membran, die die Druckdifferenz in mechanische Bewegung umwandelt. Es wurde eine kompakte Positionierung der Optik entwickelt, die es ermöglicht, die Verformung der Membran zu messen. Nach der Konstruktion des optischen Sensors wurde er in einem hydraulischen Versuchstand eingebaut. Der Sensor kann die Frequenz des Erregersignals gut messen, jedoch ist die dynamische Antwort des ganzen Systems anders als erwartet. Die Ursache dafür wurde mit einem Rohrleitungsmodell untersucht, das viskose Verluste beinhaltet, aber auch dieses Modell konnte keine hundertprozentige Systemantwort liefern. Die Messungen wurden durch Lufteinschlüsse der Messflüssigkeit und Resonanzfrequenzen des Versuchstandes gestört. Dennoch konnte die Funktion des Sensors bei der Erkennung eines gebrochenen Zahnes einer Zahnradpumpe nachgewiesen werden.

Within automotive industry, Noise, Vibration and Harshness (NVH) has emerged to be one of the main research topics. Unlike attributes such as vehicle safety, drivability, and durability which are functionality criteria, NVH is closely tied to quality and comfort of the ride. The recent trend in consumer market shows that NVH is becoming increasingly important in purchasing decisions and can significantly affect competitive edge of vehicles. Among various factors that contribute to vehicle noise, pressure pulsation inside vehicle fuel system has been subject to studies for several decades. In gasoline vehicles, with the introduction and wide spread of returnless fuel delivery system, the pressure pulsation phenomenon has become more and more prominent and has raised several issues, including noise. Similar phenomenon can be found in EVAP system where pressure is small. However, the information regarding pressure pulsation and noise issue in EVAP system is very limited. This thesis investigated the noise issue caused by pressure pulsation inside EVAP system of a current production vehicle by one of the major automotive Original Equipment Manufacturers (OEM). There are two main parts in this research. First part is to build a test stand integrating the original parts provided by the OEM to re-create the noise, then to observe and collect data on the noise issue to understand the noise generation mechanism. Second part of this research is to, through literature survey, generate ideas on noise reduction, and then to test these ideas. Due to limited information, literature survey was focused on researches done on the fuel delivery system. By collecting and analyzing pressure data on various running conditions, utilizing inspection camera, and carefully designed experiments, this research made findings on pressure pulsation and noise phenomenon, examined possible scenarios for the noise generation mechanism, and provided key evidences regarding various components and their effects on the pressure pulsation/noise. This thesis presented 8 different approaches to achieve noise reduction. Among those, 5 focused on pressure pulsation attenuation, which heavily drew inspiration from pulsation attenuation methods used in fuel delivery system. The methods tested in this thesis achieved various degree of success in noise reduction. However, each had its own drawbacks: they caused flow restriction in the line, and/or reduced the vacuum level going to the fuel tank system, and/or required design changes on critical parts in the system.