{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/13460"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/13460","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"Shockless explosion combustion - Controlled autoignition in stratified mixtures for pressure gain combustion","abstract":"This work investigates the reliable generation of a homogeneous autoignition in a reactive mixture flow as a pressure gain combustion approach. Pressure gain combustion represents a promising concept to achieve an increase in the thermal efficiency of gas turbine applications compared to conventional constant pressure combustion. The concept is based on a pulsating operation with high frequency injection of a defined mixture profile into a continuous air flow that undergoes homogeneous autoignition. The injected fuel profile has been tailored to compensate for the gradient in residence time and hence, enable the simultaneous ignition of the entire combustor volume leading to an aerodynamic confinement which ultimately results in an increase in pressure. This pressure rise is highly dependent on the homogeneity of the autoignition which can be characterized by the number of quasi-simultaneous ignitions occurring inside the combustor volume. An increased homogeneity results in a greater pressure rise and simultaneously minimized the occurrence of shock waves. This type of combustion is termed as shockless explosion combustion (SEC). The main objective of this work is investigate the SEC process experimentally and enable a repeatable and reliable operation which has been realized within the frame of four publications. First, an initial test rig was modified to allow for the precise injection of a desired fuel profile into a continuous air flow and subsequently observe autoignition within a desired combustor section. Secondly, optical measurement techniques were applied to quantify the successful injection of the desired fuel profile which stays largely preserved during convection in the combustor. As a next step, the correlation between three model injection profiles and the resulting autoignition was investigated. A significant and reproducible influence of the fuel injection on the ignition distribution is observed. These observations are subsequently used to apply an extremum seeking control algorithm which controls the cycle–averaged formation of different autoignition modes by optimizing the fuel injection profile. Optical and pressure measurements reveal a complex interaction between heat release and pressure waves influenced by low and high temperature chemistry of the applied fuel. Four different modes of ignition have been identified which are classified, namely: turbulent deflagration, subsonic autoignition, supersonic autoignition, and aerodynamic confinement by multiple simultaneous ignition fronts. The results presented in this work, demonstrate the experimental feasibility of a shockless explosion combustion. It was shown that autoignition, which is primarily driven by chemical kinetics, and thus, highly sensitive to perturbations, can be greatly affected by the injected fuel profile. The amplitude of the pressure rise was found to viii strongly correlate with the autoignition homogeneity. Moreover, it was found that the autoignition modes observed, are impacted by the applied fuel which exhibits multi-stage ignition behavior. These fuel characteristics can be exploited to trigger different modes of autoignition by the proper adjustment of the injected fuel trajectory. By this, the probability of the occurrence of distinct autoignition modes can be greatly impacted, which was shown by the successful application of a closed-loop control algorithm.","abstract_html":"This work investigates the reliable generation of a homogeneous autoignition in a reactive mixture flow as a pressure gain combustion approach. Pressure gain combustion represents a promising concept to achieve an increase in the thermal efficiency of gas turbine applications compared to conventional constant pressure combustion. The concept is based on a pulsating operation with high frequency injection of a defined mixture profile into a continuous air flow that undergoes homogeneous autoignition. The injected fuel profile has been tailored to compensate for the gradient in residence time and hence, enable the simultaneous ignition of the entire combustor volume leading to an aerodynamic confinement which ultimately results in an increase in pressure. This pressure rise is highly dependent on the homogeneity of the autoignition which can be characterized by the number of quasi-simultaneous ignitions occurring inside the combustor volume. An increased homogeneity results in a greater pressure rise and simultaneously minimized the occurrence of shock waves. This type of combustion is termed as shockless explosion combustion (SEC). The main objective of this work is investigate the SEC process experimentally and enable a repeatable and reliable operation which has been realized within the frame of four publications. First, an initial test rig was modified to allow for the precise injection of a desired fuel profile into a continuous air flow and subsequently observe autoignition within a desired combustor section. Secondly, optical measurement techniques were applied to quantify the successful injection of the desired fuel profile which stays largely preserved during convection in the combustor. As a next step, the correlation between three model injection profiles and the resulting autoignition was investigated. A significant and reproducible influence of the fuel injection on the ignition distribution is observed. These observations are subsequently used to apply an extremum seeking control algorithm which controls the cycle–averaged formation of different autoignition modes by optimizing the fuel injection profile. Optical and pressure measurements reveal a complex interaction between heat release and pressure waves influenced by low and high temperature chemistry of the applied fuel. Four different modes of ignition have been identified which are classified, namely: turbulent deflagration, subsonic autoignition, supersonic autoignition, and aerodynamic confinement by multiple simultaneous ignition fronts. The results presented in this work, demonstrate the experimental feasibility of a shockless explosion combustion. It was shown that autoignition, which is primarily driven by chemical kinetics, and thus, highly sensitive to perturbations, can be greatly affected by the injected fuel profile. The amplitude of the pressure rise was found to viii strongly correlate with the autoignition homogeneity. Moreover, it was found that the autoignition modes observed, are impacted by the applied fuel which exhibits multi-stage ignition behavior. These fuel characteristics can be exploited to trigger different modes of autoignition by the proper adjustment of the injected fuel trajectory. By this, the probability of the occurrence of distinct autoignition modes can be greatly impacted, which was shown by the successful application of a closed-loop control algorithm.","abstract_has_math":false,"creators":["Yücel, Fatma Cansu"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Paschereit, Christian Oliver","Klein, Rupert"],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021","date_published":"2021","updated_at":"2026-07-27T21:28:44Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://dx.doi.org/10.14279/depositonce-12246"],"render_values":[{"text":"http://dx.doi.org/10.14279/depositonce-12246","href":"http://dx.doi.org/10.14279/depositonce-12246","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/13460","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Paschereit, Christian Oliver","Klein, Rupert"]},{"key":"dc:creator","label":"Author","values":["Yücel, Fatma Cansu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2021-11-02T15:34:29Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2021-11-02T15:34:29Z"]},{"key":"dc:date.issued","label":"Date","values":["2021"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/13460","http://dx.doi.org/10.14279/depositonce-12246"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This work investigates the reliable generation of a homogeneous autoignition in a reactive mixture flow as a pressure gain combustion approach. Pressure gain combustion represents a promising concept to achieve an increase in the thermal efficiency of gas turbine applications compared to conventional constant pressure combustion. The concept is based on a pulsating operation with high frequency injection of a defined mixture profile into a continuous air flow that undergoes homogeneous autoignition. The injected fuel profile has been tailored to compensate for the gradient in residence time and hence, enable the simultaneous ignition of the entire combustor volume leading to an aerodynamic confinement which ultimately results in an increase in pressure. This pressure rise is highly dependent on the homogeneity of the autoignition which can be characterized by the number of quasi-simultaneous ignitions occurring inside the combustor volume. An increased homogeneity results in a greater pressure rise and simultaneously minimized the occurrence of shock waves. This type of combustion is termed as shockless explosion combustion (SEC). The main objective of this work is investigate the SEC process experimentally and enable a repeatable and reliable operation which has been realized within the frame of four publications. First, an initial test rig was modified to allow for the precise injection of a desired fuel profile into a continuous air flow and subsequently observe autoignition within a desired combustor section. Secondly, optical measurement techniques were applied to quantify the successful injection of the desired fuel profile which stays largely preserved during convection in the combustor. As a next step, the correlation between three model injection profiles and the resulting autoignition was investigated. A significant and reproducible influence of the fuel injection on the ignition distribution is observed. These observations are subsequently used to apply an extremum seeking control algorithm which controls the cycle–averaged formation of different autoignition modes by optimizing the fuel injection profile. Optical and pressure measurements reveal a complex interaction between heat release and pressure waves influenced by low and high temperature chemistry of the applied fuel. Four different modes of ignition have been identified which are classified, namely: turbulent deflagration, subsonic autoignition, supersonic autoignition, and aerodynamic confinement by multiple simultaneous ignition fronts. The results presented in this work, demonstrate the experimental feasibility of a shockless explosion combustion. It was shown that autoignition, which is primarily driven by chemical kinetics, and thus, highly sensitive to perturbations, can be greatly affected by the injected fuel profile. The amplitude of the pressure rise was found to viii strongly correlate with the autoignition homogeneity. Moreover, it was found that the autoignition modes observed, are impacted by the applied fuel which exhibits multi-stage ignition behavior. These fuel characteristics can be exploited to trigger different modes of autoignition by the proper adjustment of the injected fuel trajectory. By this, the probability of the occurrence of distinct autoignition modes can be greatly impacted, which was shown by the successful application of a closed-loop control algorithm.","Im Rahmen dieser Arbeit wird das zuverlässige und wiederholbare Erzeugen einer homogenen Selbstzündung innerhalb einer kontinuierlichen Strömung als neuartiges Konzept zur druckerhöhenden Verbrennung untersucht. Die druckerhöhende Verbrennung ist ein vielversprechender Ansatz zur Steigerung des Wirkungsgrades von Gasturbinen verglichen zur herkömmlichen Gleichdruckverbrennung. Das Konzept basiert auf einem zyklischen Betrieb bei dem ein geschichtetes Brennstoffprofil bei hohen Frequenzen in ein kontinuierlich durchströmtes Rohr eingedüst wird und anschließend homogen zündet. Das eingedüste Brennstoffprofil ist präzise geschichtet, um so den Gradienten in der Verweilzeit zu kompensieren der während des Eindüsvorgangs zustande kommt. Somit wird das gleichzeitige Zünden des gesamten Brennkammervolumens erreicht. Die daraus resultierende aerodynamische Begrenzung führt zu einem moderaten Drucksanstieg innerhalb der Brennkammer. Dieser Druckanstieg ist eine Funktion der Homogenität der Selbstzündung, welche durch die Anzahl der simultan auftretenden Zündfronten innerhalb des Brennkammervolumens charakterisiert werden kann. Eine höhere Homogenität der Selbstzündung ist einhergehend mit einer gesteigerten Druckerhöhung bei gleichzeitiger Minimierung des Auftretens von Stößen. Diese Art von Zündung wird als stoßfreie Explosionsverbrennung (englisch: shockless explosion combustion, kurz: SEC) bezeichnet. Das wesentliche Ziel dieser Arbeit ist es den SEC Prozess experimentell zu untersuchen und einen zuverlässigen und wiederholbaren Betrieb zu ermöglichen. Dies wurde im Rahmen von vier Veröffentlichungen realisiert. Hierfür wurde zunächst ein Prüfstand zur präzisen Eindüsung eines geschichteten Brennstoffprofils ausgelegt. In einem nächsten Schritt wurde, unter Anwendung optischer Messverfahren zur Konzentrationsmessung, die Kontrollierbarkeit der Brennstoffverteilung innerhalb des Brennkammervolumens durch gezielte Eindüsung gezeigt. Im Rahmen von reaktiven Verbrennungsversuchen wurden drei ausgewählte Brennstoffprofile hinsichtlich ihres Zündverhaltens untersucht. Ein signifikanter und wiederholbarer Einfluss der Befüllungskurve auf die Homogenität der Selbstzündung konnte gezeigt werden. Basierend auf diesen Beobachtungen wurde ein Regelalgorithmus zur zyklus-gemittelten Generierung verschiedener Selbstzündungsmoden durch die Optimierung der Endüsung entwickelt und angewandt. Optische Messungen in Kombination mit Druckmessungen zeigen ein komplexes Zusammenspiel zwischen Wärmefreisetzung und Druckerhöhung beeinflusst durch das Zündverhalten des verwendeten Brennstoffs. Vier verschiedene Moden der Selbstzündung wurden identifiziert: turbulente Deflagration, subsonische Selbstzündung, supersonische Selbstzündung und das simultane Entstehen mehrerer Selbstzündungen. Die Ergebnisse dieser Arbeit zeigen, dass eine stoßfreie Explosionsverbrennung experimentell realisierbar ist. Die Homogenität von Selbstzündungsprozessen wurde erfolgreich durch das gezielte Eindüsen eines geeigneten Brennstoffprofils beeinflusst. Es wurde gezeigt, dass die erzeugten Druckamplituden mit der Homogenität der Zündfront korrelieren. Weiterhin wurde beobachtet, dass die Brennstoffeingenschaften eine entscheidende Rolle bei der Entstehung bestimmter Flammmenausbreitungsmoden spielen. Diese Brennstoffeigenschaften können durch das gezielte Eindüsen eines Brennstoffprofils ausgenutzt werden, um somit bestimmte Moden zu generieren. Dies wurde im Rahmen dieser Arbeit durch die erfolgreiche Anwendung eines Reglers gezeigt."]},{"key":"dc:title","label":"Title","values":["Shockless explosion combustion - Controlled autoignition in stratified mixtures for pressure gain combustion"]}]}],"canonical_facts":{"dc:contributor.advisor":["Paschereit, Christian Oliver","Klein, Rupert"],"dc:creator":["Yücel, Fatma Cansu"],"dc:date.accessioned":["2021-11-02T15:34:29Z"],"dc:date.available":["2021-11-02T15:34:29Z"],"dc:date.issued":["2021"],"dc:description.abstract":["This work investigates the reliable generation of a homogeneous autoignition in a reactive mixture flow as a pressure gain combustion approach. Pressure gain combustion represents a promising concept to achieve an increase in the thermal efficiency of gas turbine applications compared to conventional constant pressure combustion. The concept is based on a pulsating operation with high frequency injection of a defined mixture profile into a continuous air flow that undergoes homogeneous autoignition. The injected fuel profile has been tailored to compensate for the gradient in residence time and hence, enable the simultaneous ignition of the entire combustor volume leading to an aerodynamic confinement which ultimately results in an increase in pressure. This pressure rise is highly dependent on the homogeneity of the autoignition which can be characterized by the number of quasi-simultaneous ignitions occurring inside the combustor volume. An increased homogeneity results in a greater pressure rise and simultaneously minimized the occurrence of shock waves. This type of combustion is termed as shockless explosion combustion (SEC). The main objective of this work is investigate the SEC process experimentally and enable a repeatable and reliable operation which has been realized within the frame of four publications. First, an initial test rig was modified to allow for the precise injection of a desired fuel profile into a continuous air flow and subsequently observe autoignition within a desired combustor section. Secondly, optical measurement techniques were applied to quantify the successful injection of the desired fuel profile which stays largely preserved during convection in the combustor. As a next step, the correlation between three model injection profiles and the resulting autoignition was investigated. A significant and reproducible influence of the fuel injection on the ignition distribution is observed. These observations are subsequently used to apply an extremum seeking control algorithm which controls the cycle–averaged formation of different autoignition modes by optimizing the fuel injection profile. Optical and pressure measurements reveal a complex interaction between heat release and pressure waves influenced by low and high temperature chemistry of the applied fuel. Four different modes of ignition have been identified which are classified, namely: turbulent deflagration, subsonic autoignition, supersonic autoignition, and aerodynamic confinement by multiple simultaneous ignition fronts. The results presented in this work, demonstrate the experimental feasibility of a shockless explosion combustion. It was shown that autoignition, which is primarily driven by chemical kinetics, and thus, highly sensitive to perturbations, can be greatly affected by the injected fuel profile. The amplitude of the pressure rise was found to viii strongly correlate with the autoignition homogeneity. Moreover, it was found that the autoignition modes observed, are impacted by the applied fuel which exhibits multi-stage ignition behavior. These fuel characteristics can be exploited to trigger different modes of autoignition by the proper adjustment of the injected fuel trajectory. By this, the probability of the occurrence of distinct autoignition modes can be greatly impacted, which was shown by the successful application of a closed-loop control algorithm.","Im Rahmen dieser Arbeit wird das zuverlässige und wiederholbare Erzeugen einer homogenen Selbstzündung innerhalb einer kontinuierlichen Strömung als neuartiges Konzept zur druckerhöhenden Verbrennung untersucht. Die druckerhöhende Verbrennung ist ein vielversprechender Ansatz zur Steigerung des Wirkungsgrades von Gasturbinen verglichen zur herkömmlichen Gleichdruckverbrennung. Das Konzept basiert auf einem zyklischen Betrieb bei dem ein geschichtetes Brennstoffprofil bei hohen Frequenzen in ein kontinuierlich durchströmtes Rohr eingedüst wird und anschließend homogen zündet. Das eingedüste Brennstoffprofil ist präzise geschichtet, um so den Gradienten in der Verweilzeit zu kompensieren der während des Eindüsvorgangs zustande kommt. Somit wird das gleichzeitige Zünden des gesamten Brennkammervolumens erreicht. Die daraus resultierende aerodynamische Begrenzung führt zu einem moderaten Drucksanstieg innerhalb der Brennkammer. Dieser Druckanstieg ist eine Funktion der Homogenität der Selbstzündung, welche durch die Anzahl der simultan auftretenden Zündfronten innerhalb des Brennkammervolumens charakterisiert werden kann. Eine höhere Homogenität der Selbstzündung ist einhergehend mit einer gesteigerten Druckerhöhung bei gleichzeitiger Minimierung des Auftretens von Stößen. Diese Art von Zündung wird als stoßfreie Explosionsverbrennung (englisch: shockless explosion combustion, kurz: SEC) bezeichnet. Das wesentliche Ziel dieser Arbeit ist es den SEC Prozess experimentell zu untersuchen und einen zuverlässigen und wiederholbaren Betrieb zu ermöglichen. Dies wurde im Rahmen von vier Veröffentlichungen realisiert. Hierfür wurde zunächst ein Prüfstand zur präzisen Eindüsung eines geschichteten Brennstoffprofils ausgelegt. In einem nächsten Schritt wurde, unter Anwendung optischer Messverfahren zur Konzentrationsmessung, die Kontrollierbarkeit der Brennstoffverteilung innerhalb des Brennkammervolumens durch gezielte Eindüsung gezeigt. Im Rahmen von reaktiven Verbrennungsversuchen wurden drei ausgewählte Brennstoffprofile hinsichtlich ihres Zündverhaltens untersucht. Ein signifikanter und wiederholbarer Einfluss der Befüllungskurve auf die Homogenität der Selbstzündung konnte gezeigt werden. Basierend auf diesen Beobachtungen wurde ein Regelalgorithmus zur zyklus-gemittelten Generierung verschiedener Selbstzündungsmoden durch die Optimierung der Endüsung entwickelt und angewandt. Optische Messungen in Kombination mit Druckmessungen zeigen ein komplexes Zusammenspiel zwischen Wärmefreisetzung und Druckerhöhung beeinflusst durch das Zündverhalten des verwendeten Brennstoffs. Vier verschiedene Moden der Selbstzündung wurden identifiziert: turbulente Deflagration, subsonische Selbstzündung, supersonische Selbstzündung und das simultane Entstehen mehrerer Selbstzündungen. Die Ergebnisse dieser Arbeit zeigen, dass eine stoßfreie Explosionsverbrennung experimentell realisierbar ist. Die Homogenität von Selbstzündungsprozessen wurde erfolgreich durch das gezielte Eindüsen eines geeigneten Brennstoffprofils beeinflusst. Es wurde gezeigt, dass die erzeugten Druckamplituden mit der Homogenität der Zündfront korrelieren. Weiterhin wurde beobachtet, dass die Brennstoffeingenschaften eine entscheidende Rolle bei der Entstehung bestimmter Flammmenausbreitungsmoden spielen. Diese Brennstoffeigenschaften können durch das gezielte Eindüsen eines Brennstoffprofils ausgenutzt werden, um somit bestimmte Moden zu generieren. Dies wurde im Rahmen dieser Arbeit durch die erfolgreiche Anwendung eines Reglers gezeigt."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/13460","http://dx.doi.org/10.14279/depositonce-12246"],"dc:language.iso":["en"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Shockless explosion combustion - Controlled autoignition in stratified mixtures for pressure gain combustion"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:44Z"}