An atmospheric pressure swirl-stabilized methane-air burner has been developed as a test platform for nanosecond repetitively pulsed (NRP) discharge plasma-assisted combustion research. Qualitative flame and plasma discharge characterizations were conducted with high-speed video and low-light ICCD imagery, along with a modal acoustic analysis of the entire assembly. A large eddy simulation (LES) of the burner was created using the commercial solver Ansys Fluent to investigate the plasma effects on swirl-stabilized turbulent combustion. A modified version of the solver's premixed combustion mechanism is presented along with a phenomenological plasma discharge model to simulate plasma-assisted combustion. Cold flow particle image velocimetry (PIV) data were collected to validate the non-reacting flow field and assess non-reacting NRP discharge effects. Optical emission spectroscopy (OES) measurements of the second positive system (SPS) of nitrogen mapped temperature characteristics of NRP discharge bursts for comparison to time-resolved simulation data. Finally, time-averaged CH* chemiluminescence data were collected to qualitatively assess the effects of plasma on the experimental burner and simulated flame structure. Overall, the phenomenologically-based combustion mechanism proposed in this work shows good agreement with several experimental observations and provides a promising framework for future plasma-assisted combustion modeling.

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Eleven gas species, including CO, CO2, H2, H2O, H2S, HCl, NOX, O2, SO2, COS and SO3, were measured in a 150 kWth, staged, pulverized coal, down-fired combustor using a Fourier transform infrared (FTIR) spectrometer, gas chromatograph (GC), and a Horiba PG-250 5-gas analyzer. Additional gases such as HCN, NH3, CH4, and other hydrocarbons were also measured. Seven coals of varying rank and composition were investigated. Measurements were obtained in reducing (S.R. = 0.85) and oxidizing (S.R. = 1.15) conditions. In particular, sulfur- and chlorine-containing species including H2S, SO2, COS, SO3, and HCl are discussed. In the reducing zone, all four measured sulfur species were present although SO3 was only 1-3% of the total coal sulfur. A trade-off between SO2, H2S, and COS was clearly identifiable according to S.R. H2S and COS increased and SO2 decreased in highly reducing or high-CO regions. The total amount of sulfur in the measured species in the reducing zone was estimated to be about 65-80% of the total coal sulfur. The total amount of sulfur measured in the four gases increased linearly with coal sulfur in both the oxidizing and reducing zones for the seven coals considered. In the oxidizing zone, SO3 remained low (1-3% of total sulfur) with the only other measurable sulfur bearing species being SO2. Chlorine was found to be released in the reducing zone and form primarily HCl. As the HCl was transported into the oxidizing region, the chlorine remained as HCl. Measurement of HCl was difficult, making some of the data incomplete. The HCl concentration was found to be affected by the flow rate of gases into the sampling line and gas analyzers suggesting HCl is highly reactive and needs to be quenched rapidly or it will react during sampling. Several trends in the data were matched by equilibrium calculations including trends for H2S, COS and SO2 in both reducing and oxidizing conditions. SO3 did not match equilibrium although the amount of SO3 was proportional to the amount of sulfur in the coal. HCl, though consistent with cited literature for several coals, did not agree with equilibrium trends or values.

This degree project is focused on the study of the tumble and the swirlmotions, which develop during the intake stroke, inside a cylinder of a Dieselengine.Nowadays, the reduction of fuel consumption and emissions is a primaryaspect for automotive companies, including Scania. Then, an efficient combustionprocess is required, and a fundamental role is played by tumble andswirl motion.These motions have been studied by means of the Particle Image Velocimetry(PIV) technique. In particular, two different cylinder head designshave been investigated, focusing on the structures present in the flow andtheir evolutions inside the cylinder. Finally, these results have been comparedwith LES results, in order to validate the latest. Analysing the swirl motion, it has been possible to identify three mainregions, along the cylinder, characterized by different vortex structures. Inaddition, the velocity field into the entire cylinder volume has been extractedby means of a three-dimensional three-component reconstruction.

To simulate crowds of people is of great social interest and is also believed to be useful when analyzing situations involving denser crowds. Many simulators seen over the years have however been struggling with simulating larger number of people, often due to a computationally expensive collision avoidance step. Furthermore, many simulators seems to forget the fact that people tend to stick together in smaller social groups rather than walking alone. A simulator for high density crowds has nevertheless been implemented through modeling crowds as a unilateral incompressible fluid. Together with an integration of groups onto this approach, the obtained solution allows for real time simulation of up to 3000 virtual people. The impact of having groups in simulations has furthermore been set as the overall goal of the thesis and has been analyzed through observing the effects of groups in various scenarios. A smaller user study has also been conducted in order to gain perceptual insights of groups in various crowd densities. These have shown that groups have a smaller impact on the crowd flow, and do not put a larger strain on the performance of the simulation. Groups are further proved to be perceived differently in different densities, with a possible difficulty for scenarios in higher density. / Att simulera folkmassor är av stort socialt intresse och tros även vara till nytta när man analyserar situationer som berör mer kompaktare folkmassor. Många tidigare simulationer har dock kämpat med att simulera större folkmassor, oftast på grund av höga beräkningskostnader mot förhindrandet av att två eller fler virtuella människor kolliderar in i varandra. Dessutom verkar många simulationer glömma bort att människor oftast går i mindre sociala grupper snarare än att gå var och för sig hela tiden. En simulering har trots detta gjorts genom att modellera folkmassor som en unilateral inkompressibel vätska. Tillsammans med en integration av grupper på detta tillvägagångssätt har lösningen visat sig alltsomallt ge simulation i realtid för uppemot 3000 virtuella människor. Effekten av att ha grupper i simulationer har vidare analyserats i en rad olika scenarion. En mindre användarstudie har också gett insikter i hur grupper uppfattas i olika kompakta folkmassor. Resultat har visat att grupper har en mindre effekt på folkmassor i det stora hela, och lägger inte en alltför stor påfrestning på simulationers prestanda. Det har också bevisats att grupper uppfattas annorlunda i olika kompakta folkmassor, med en viss möjlighet till svårare uppfattning i högre, mer kompakta folkmassor.

This thesis work aimed at increasing the knowledge regarding phenomena occurring when gas is injected using a top-blown lance on to a bath. All results are based on physical modeling studies carried out both using low and high gas flow rates and nozzle diameters ranging from 0.8 mm to 3.0 mm. At the low gas flow rates, the penetration depth in the bath was studied. The experiments focused on studying the effect of nozzle diameter, lance height and gas flow rate on the penetration depth. It was found that the penetration depth increases with decreasing nozzle diameter, decreasing lance height and with increasing gas flow rate. The results were also compared with previous work. More specifically, it was studied how the previous published empirical relationships fitted the current experimental data. It was found that the relationships of Banks [1], Davenport [2], Chatterjee [3] and Qian [4] agreed well with the experimental data of this investigation for nozzle diameters of 2.0 mm and 3.0 mm. However, for smaller nozzle diameters there were considerable deviations. Therefore, a new correlation heuristically derived from energy conservation consideration was suggested and showed better agreement for small nozzle diameters. The experiments carried out at higher gas flow rates focused on the study of swirl motion. The effects of nozzle diameter, lance height, gas flow rate and aspect ratio on the swirl motion were investigated. The amplitude and period of the swirl as well as the starting time and the damping time of the swirl were determined. The amplitude was found to increase with an increased nozzle diameter and gas flow rate, while the period had a constant value of about 0.5 s for all nozzle diameters, gas flow rates and lance heights. The starting time for the swirl motion was found to decrease with an increased gas flow, while the damping time was found to be independent of gas flow rate, nozzle diameter, lance height and ratio of depth to diameter. / QC 20101217

As a contribution to advancing turbofan engine ground test technology in support of propulsion system integration in modern conceptual aircraft, a novel inlet distortion generator (ScreenVaneTM) was invented. The device simultaneously reproduces combined inlet total pressure and swirl distortion elements in a tailored profile intended to match a defined turbofan engine inlet distortion profile. The device design methodology was intended to be sufficiently generic to be utilized in support of any arbitrary inlet distortion profile yet adequately specific to generate high-fidelity inlet distortion profile simulation. For the current investigation, a specific inlet distortion profile was defined using computational analysis of a conceptual boundary layer ingesting S-duct turbofan engine inlet. The resulting inlet distortion profile, consisting of both total pressure and swirl distortion elements, was used as the objective profile to be matched by the ScreenVane in a turbofan engine ground test facility. A ScreenVane combined inlet total pressure and swirl distortion generator was designed, computationally analyzed, and experimentally validated. The design process involved specifying a total pressure loss screen pattern and organizing a unique arrangement of swirl inducing turning vanes. Computational results indicated that the ScreenVane manufactured distortion profile matched the predicted S-duct turbofan engine inlet manufactured distortion profile with excellent agreement in pattern shape, extent, and intensity. Computational full-field total pressure recovery and swirl angle profiles matched within approximately 1% and 2.5° (RMSD), respectively. Experimental turbofan engine ground test results indicated that the ScreenVane manufactured distortion profile matched the predicted S-duct turbofan engine inlet manufactured distortion profile with excellent agreement in pattern shape, extent, and intensity. Experimental full-field total pressure recovery and swirl angle profiles matched within approximately 1.25% and 3.0° (RMSD), respectively. Following the successful reproduction of the S-duct turbofan engine inlet manufactured distortion profile, a turbofan engine response evaluation was conducted using the validated ScreenVane inlet distortion generator. Flow measurements collected at discrete planes immediately upstream and downstream of the fan rotor isolated the component for performance analysis. Based on the results of this particular engine and distortion investigation, the adiabatic fan efficiency was negligibly altered while operating with distorted inflow conditions when compared to nominal inflow conditions. Fuel flow measurements indicated that turbofan engine inlet air mass flow specific fuel consumption increased by approximately 5% in the presence of distortion. While a single, specific turbofan engine inlet distortion profile was studied in this investigation, the ScreenVane methodology, design practices, analysis approaches, manufacturing techniques, and experimental procedures are applicable to any arbitrary, realistic combined inlet total pressure and swirl distortion. / Doctor of Philosophy / As a contribution to advancing turbofan engine ground test technology in support of propulsion system integration in modern conceptual aircraft, a novel inlet distortion generator (ScreenVaneTM) was invented. The device simultaneously reproduces combined inlet total pressure and swirl distortion elements in a tailored profile intended to match a defined turbofan engine inlet distortion profile. The device design methodology was intended to be sufficiently generic to be utilized in support of any arbitrary inlet distortion profile yet adequately specific to generate high-fidelity inlet distortion profile simulation. For the current investigation, a specific inlet distortion profile was defined using computational analysis of a conceptual boundary layer ingesting S-duct turbofan engine inlet. The resulting inlet distortion profile, consisting of both total pressure and swirl distortion elements, was used as the objective profile to be matched by the ScreenVane in a turbofan engine ground test facility. A ScreenVane combined inlet total pressure and swirl distortion generator was designed, computationally analyzed, and experimentally validated. The design process involved specifying a total pressure loss screen pattern and organizing a unique arrangement of swirl inducing turning vanes. Computational and experimental results indicated that the ScreenVane manufactured distortion profile matched the predicted S-duct turbofan engine inlet manufactured distortion profile with excellent agreement in pattern shape, extent, and intensity. Following the successful reproduction of the S-duct turbofan engine inlet manufactured distortion profile, a turbofan engine response evaluation was conducted using the validated ScreenVane inlet distortion generator. Flow measurements collected at discrete planes immediately upstream and downstream of the fan rotor isolated the component for performance analysis. Based on the results of this particular engine and distortion investigation, the adiabatic fan efficiency was negligibly altered while operating with distorted inflow conditions when compared to nominal inflow conditions. Fuel flow measurements indicated that turbofan engine inlet air mass flow specific fuel consumption increased in the presence of distortion. While a single, specific turbofan engine inlet distortion profile was studied in this investigation, the ScreenVane methodology, design practices, analysis approaches, manufacturing techniques, and experimental procedures are applicable to any arbitrary, realistic combined inlet total pressure and swirl distortion.

The use of serpentine boundary layer ingesting (BLI) diffusers offers a significant benefit to the performance of Blended Wing Body aircraft. However, the inherent diffuser geometry combined with a thick ingested boundary layer creates strong secondary flows that lead to severe flow distortion at the engine face, increasing the possibility of engine surge. This study investigated the use of enabling active flow control methods to reduce engine-face distortion. An ejector-pump based system of fluidic actuators was used to directly manage the diffuser secondary flows. This system was modeled computationally using a boundary condition jet modeling method, and tested in an ejector-driven wind tunnel facility. This facility is capable of simulating the high-altitude, high subsonic Mach number conditions representative of BWB cruise conditions, specifically a cruise Mach number of 0.85 at an altitude of 39,000 ft. The tunnel test section used for this experiment was designed, built, and tested as a validation tool for the computational methods. This process resulted in the creation of a system capable of efficiently investigating and testing the fundamental mechanisms of flow control in BLI serpentine diffusers at a minimum of time and expense. Results of the computational and wind tunnel analysis confirmed the large potential benefit of adopting fluidic actuators to control flow distortion in serpentine BLI inlets. Computational analysis showed a maximum 71% reduction in flow distortion at the engine face through the use of the Pyramid 1 ejector scheme, and a 68% reduction using the Circumferential ejector scheme. However, the flow control systems were also found to have a significant impact on flow swirl. The Pyramid 1 ejector scheme was found to increase AIP flow swirl by 64%, while the Circumferential ejector scheme reduced flow swirl by 30%. Computational analyses showed that this difference was the result of jet interaction. By keeping the jet flows separate and distinct, the diffuser secondary flows could be more efficiently managed. For this reason, the most practically effective flow control scheme was the Circumferential ejector scheme. Experimental results showed that the computational analysis slightly over-predicted flow distortion. However, the trends are accurately predicted despite slight variances in freestream Mach number between runs and a slightly lower tested altitude. / Master of Science

Due to global warming, all industries must do everything they can to prevent temperature increases. In this bachelor thesis, the reader will get a description of how the marine industry is tackling the environmental problem and more precisely what a vessel can be equipped with to reduce fuel consumption.   The thesis deals with how different energy saving devices (ESD) affect the propulsion efficiency of a chemtanker sailing on the sea. The thesis will address the following three different concept: Pre-swirl stator, Pre-swirl duct, Pre-duct. The work will step-by-step describe the different optimization parameters that need to be adjusted and what impact these parameters have on the wake field of the propeller plane.  The work addresses some different devices that will reduce the fuel consumption of ships and that these devices not only reduce fuel consumption, but also have a positive impact on cavitation. The result of this thesis was that ESD will reduce the power needed to reach the desired speed of the vessel and after post-processing was made, the best result, which was Pre-swirl stator, showed an energy saving percentage of as much as 3.15% and the risk of cavity occurring at the propeller tip was also reduced.

The prevalence of gas turbines operating in primarily lean premixed modes is predicated on the need for lower emissions and increased efficiency. An enhancement in the mixing process through the introduction of swirl in the combustion reactants is also necessary for flame stabilization. The resulting lean swirling flames are often characterized by a susceptibility to feedback between velocity, pressure and heat release perturbations with a potential for unstable self-amplifying dynamics. The existing literature on combustion dynamics is predominantly dedicated to premixed flame configurations motivated by power generation and propulsive gas turbine applications. In the present research effort, an investigation into the response of atmospheric, non-premixed swirling flames to acoustic perturbations at various frequencies (fp = 0-315Hz) and swirl intensities (S=0.09 and S=0.34) is carried out. The primary objective of the research effort is to broaden the scope of fundamental understanding in flame dynamics in the literature to include non-premixed swirling flames. Applications of the research effort include control strategies to mitigate the occurrence of thermoacoustic instabilities in future power generation gas turbines. Flame heat release is quantitatively measured using a photomultiplier with a 430nm bandpass filter for observing CH* chemiluminescence which is simultaneously imaged with a phase-locked CCD camera. Acoustic perturbations are generated with a loudspeaker at the base of an atmospheric co-flow burner with resulting velocity oscillation amplitudes, u'/Uavg in the 0.03-0.30 range. The dependence of flame dynamics on the relative richness of the flame is investigated by studying various constant fuel flow rate flame configurations. The effect of varying fuel flow rates on the flame response is also examined using with dynamic time-dependent fuel supply rates over the data acquisition period. The Particle Image Velocimetry (PIV) method is used to study the isothermal flow field associated with acoustic pulsing. The acoustic impedance, wavelet analysis, Rayleigh criteria and phase conditioning methods are used to identify fundamental mechanisms common to highly responsive flame configurations.