Schlieren measurements in the round cylinder of an optically accessible internal combustion engine

Kaiser, Sebastian; Salazar, Victor M.; Hoops, Alexandra A.

doi:10.1364/ao.52.003433

Cited by 19 publications

(16 citation statements)

References 26 publications

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“…Consequently, the application of the technique in interesting environments, such as the in-cylinder flow field of an IC engine, requires special attention. Previous attempts at using qualitative schlieren visualisation in situations where optical access is provided through curved optical surfaces in engines have been reported in [7][8][9]. One approach places appropriate lenses in front and after the curved engine cylinder windows [8], aiming to reshape the incoming parallel light when it passes through the engine cylinder.…”

Section: Introductionmentioning

confidence: 99%

Schlieren-based temperature measurement inside the cylinder of an optical spark ignition and homogeneous charge compression ignition engine

et al. 2015

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Schlieren [1, 2] is a non-intrusive technique that can be used to detect density variations in a medium, and thus, under constant pressure and mixture concentration conditions, measure whole field temperature distributions.The objective of the current work was to design a schlieren system to measure line-of-sight averaged temperature distribution with the final aim to determine the temperature distribution inside the cylinder of Internal Combustion engines. In a preliminary step, we assess theoretically the errors arising from the data reduction used to determine temperature from a schlieren measurement and find that the total error, random and systematic, is less than 3%, for typical conditions encountered in the present experiments. A Z-type, curved-mirror schlieren system was used to measure the temperature distribution from a hot air jet in an open air environment in order to evaluate the method. Using the Abel transform, the radial distribution of the temperature was reconstructed from the line of sight measurements. There was good agreement in the peak temperature between the reconstructed schlieren and thermocouple measurements. Experiments were then conducted in a four-stroke, single-cylinder, optical spark ignition engine with a four-valve, pentroof-type cylinder head to measure the temperature distribution of the reaction zone of an iso-octane-air mixture. The engine optical windows were designed to produce parallel rays and allow accurate application of the technique. The feasibility of the method to measure temperature distributions in IC engines was evaluated with simulations of the deflection angle combined with equilibrium chemistry calculations that estimated the temperature of the reaction zone at the position of maximum ray deflection as recorded in a schlieren image. Further simulations showed that the effects of exhaust gas recirculation and air-to-fuel ratio on the schlieren images were minimal under engine conditions compared to the temperature effect. At 20 crank angle degrees before top dead centre (i.e. 20 crank angle degrees after ignition timing), the measured temperature of the flame front was in agreement with the simulations (730-1320 K 2 depending on the shape of the flame front). Furthermore, the schlieren images identified the presence of hot gases ahead of the reaction zone due to diffusion and showed that there were no hot spots in the unburned mixture.

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Section: Introductionmentioning

confidence: 99%

Schlieren-based temperature measurement inside the cylinder of an optical spark ignition and homogeneous charge compression ignition engine

et al. 2015

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“…The natural progression from a flat plate window is to a fixed radius constant thickness transparent cylinder. Kaiser et al (2013) investigated the use of a thick, pressure resistant transparent cylinder in order to analyse the combustion within an engine with Schlieren imaging. Without any compensation the cylinder acts as a negative cylindrical lens.…”

Section: The Use Of Curved Geometries In Opticsmentioning

confidence: 99%

“…Without any compensation the cylinder acts as a negative cylindrical lens. This causes the beam to diverge heavily, meaning only the light travelling on the central portion of the optical path would extend to the sensor (Kaiser et al, 2013). Figure 5 shows the expected divergence of light as it passes through the cylinder.…”

Section: The Use Of Curved Geometries In Opticsmentioning

confidence: 99%

“…(Kaiser et al, 2013) By using surfaces with positive refractive power the divergent effect of the cylinder can be compensated resulting in a wide field of view. It was noted that to achieve this, off the shelf parts are not available and will most likely require manufacture (Kaiser et al, 2013). The following figure demonstrates this method of compensating for the transparent cylinder.…”

Section: The Use Of Curved Geometries In Opticsmentioning

confidence: 99%

“…The following figure demonstrates this method of compensating for the transparent cylinder. (Kaiser et al, 2013) Although this research is focused on Schlieren imaging, it is relevant to any optical technique.…”

Section: The Use Of Curved Geometries In Opticsmentioning

confidence: 99%

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Thermal imaging of ducted hypersonic flows

Fredatovich¹

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The development of scramjet technology has presented the need for methods to analyse the temperature of the hypersonic flow experienced internally by the scramjet. A new technique has been proposed that incorporates an infrared window in the wall of a duct, a thin black film is placed between the flow and the window. This allows an infrared sensor to measure the surface temperature by reading the radiation emitted from the underside of the film, through the window.A semi-infinite analysis was performed on the thin film, assuming the material was either a graphite coating, or a Krylon™ matte black paint coating. It was found that the graphite film would have to be below 14μm, and the Krylon™ film below 4.5μm for the temperature on the underside of the film to experience a third of the change seen by the surface. Magnesium fluoride was chosen for the IR window due to its transmissivity and material properties. Bench tests were performed by applying heat to one side of the film, and measuring the cooling of either side with IR sensors. This showed a trend for temperature decrease but with a temperature difference of 35°C with the Krylon™ film. The graphite film showed similar trends with a larger temperature difference between surfaces, which is thought to be due to the calibration process only being performed on the paint.An experiment was carried out in the X2 expansion tube using both the painted film and graphite film, and two flow conditions; a Venus atmospheric entry condition and an air condition. Analysis with Schultz and Jones' (1973) exact thin film theory showed an increase in temperature was expected for the graphite film underside, but was unlikely with the painted film. The painted film showed an oscillating response followed by a 40°C, and 20°C temperature change in the Venus and air conditions, respectively. The graphite film shows a temperature change of 325°C and 150°C for the Venus and air conditions, respectively. It was concluded that the Krylon™ film is likely due to errors because of the trend, whilst the graphite film is too transmissive at its current thickness of 5-6μm.The new method of infrared thermography to measure ducted hypersonic flows remains invalidated, which was the main aim of this study. A greater understanding has been gained, and in future development it is recommended that a thicker graphite film is used, or other carbon materials researched, and that the calibration process is undertaken in the exact conditions of which the experiment will be performed.ii AcknowledgementsThe completion of this thesis has been a large undertaking and would not have been possible without the assistance and expertise of a number of people. I would like to acknowledge the following people:Prof Richard Morgan; His wealth of knowledge and experience often provided a simple solution to a complex task, and despite a large number of responsibilities he was always able to make time to discuss this thesis.All of the post-graduate students within the X-labs. Everyone has helped me in one way o...

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Trends und Herausforderungen bei der Entwicklung von Wasserstoffmotoren

Kubach,

Bucherer,

Gerber

et al. 2023

Chemie Ingenieur Technik

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Auf dem Weg zu einer klimaneutralen Mobilität können Wasserstoffmotoren vor allem im Bereich der Nutzfahrzeuge einen entscheidenden Beitrag leisten. Die Basistechnologie der Motoren ist bereits vorhanden und kann durch geringe Modifikationen angepasst werden. Der vorliegende Artikel beschreibt Trends bei der Wasserstoffmotorenentwicklung und wie deren Herausforderungen gemeistert werden können. Neben Aspekten der Infrastruktur und des Gesamtfahrzeugkonzepts stehen vor allem die Punkte Gemischbildung, Verbrennung und Emissionen im Fokus.

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Schlieren measurements in the round cylinder of an optically accessible internal combustion engine

Cited by 19 publications

References 26 publications

Schlieren-based temperature measurement inside the cylinder of an optical spark ignition and homogeneous charge compression ignition engine

Schlieren-based temperature measurement inside the cylinder of an optical spark ignition and homogeneous charge compression ignition engine

Thermal imaging of ducted hypersonic flows

Trends und Herausforderungen bei der Entwicklung von Wasserstoffmotoren

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