@misc{WillerLehmannAmtsfeld, author = {Willer, Lars and Lehmann, Knut and Amtsfeld, Philipp}, title = {Turbinenleitrad einer Gasturbine}, language = {de} } @inproceedings{NouriLehmannKuehhorn, author = {Nouri, Behnam and Lehmann, Knut and K{\"u}hhorn, Arnold}, title = {Investigations on Nusselt Number Enhancement in Ribbed Rectangular Turbine Blade Cooling Channels of Different Aspect Ratios and Rotation Numbers}, series = {ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, San Antonio, Texas, USA, June 3-7, 2013, Vol. 3A, Heat Transfer, Paper GT2013-94710}, booktitle = {ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, San Antonio, Texas, USA, June 3-7, 2013, Vol. 3A, Heat Transfer, Paper GT2013-94710}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-5514-0}, doi = {10.1115/GT2013-94710}, pages = {11}, abstract = {In the drive for higher cycle efficiencies in gas turbine engines, turbine blades are seeing an increasingly high heat load. This in turn demands improvements in the internal cooling system and a better understanding of both the level and distribution of the internal heat-transfer. A typical approach to enhance the internal cooling of the turbine blade is by casting angled 'low blockage' ribs on the walls of the cooling channels. The objective of the present paper is to determine the detailed Nusselt number distribution in rectangular internal channels with ribs. This knowledge can be used to guide the overall design e.g. to achieve high levels of heat-transfer where required. The effects of rotation as well as the interaction effects of the position and direction of ribs on opposite walls of the cooling channel have been investigated. Numerical calculations have been carried out using the commercial CFD code Fluent to investigate the local Nusselt number enhancement factor in rectangular ducts of different aspect ratios (0.5, 1 and 2) which have 45° or 90° angled ribs located on two opposite walls. This has been studied for different Rotation number Ro (0-0.45) and with a Reynolds number >30000. The first series of studies has been carried out with the same experimental setup as by Han [1]. The geometry was slightly changed to avoid the effect of high heat transfer at the entry. This study identifies important vortical structures, which are dependent on the direction and the position of the ribs. This has a profound effect on the distribution of heat-transfer within the passage. It is shown that the two smooth walls of the duct have different average Nusselt number ratio Nu/NuFD enhancement depending on the rib angle. In addition, based on numerical investigations, simple correlations have been developed for the rotational influence of the internal Nusselt number distribution. A major finding is that the effect of rotation is dominant for low aspect ratio channels and the local enhancement due to the rib position and angle is more dominant for high aspect ratio channels.}, language = {en} } @misc{WillerLehmannAmtsfeld, author = {Willer, Lars and Lehmann, Knut and Amtsfeld, Philipp}, title = {Turbinenleitrad einer Gasturbine}, abstract = {Die Erfindung betrifft ein Turbinenleitrad einer Gasturbine mit mehreren um den Umfang beabstandet angeordneten Leitschaufeln. Dabei ist vorgesehen, dass zwei benachbarte Leitschaufeln jeweils zwischen der Saugseite der einen Leitschaufel und der Druckseite der anderen Leitschaufel ausgehend von der Schaufelhinterkante eine Passage ausbilden, welche einen konstanten Passagenabschnitt umfasst, in dem die Passage einen im Wesentlichen konstanten Passagenquerschnitt aufweist. Der konstante Passagenabschnitt weist einen Eintrittsbereich und einen Austrittsbereich auf. Jede Leitschaufel bildet druckseitig einen hinteren Bereich aus, der sich ausgehend von der Schaufelhinterkante angrenzend an den konstanten Passagenabschnitt bis zum Eintrittsbereich des Passagenabschnitts erstreckt, und bildet druckseitig einen vorderen Bereich aus, der sich stromaufw{\"a}rts des hinteren Bereichs erstreckt. Es ist vorgesehen, dass jede Leitschaufel auf der Druckseite eine konvexe Druckseitenkontur aufweist, die einen {\"U}bergang vom hinteren Bereich der Leitschaufel zum vorderen Bereich der Leitschaufel herstellt.}, language = {de} } @misc{WillerLehmannAmtsfeld, author = {Willer, Lars and Lehmann, Knut and Amtsfeld, Philipp}, title = {Turbine guide wheel}, language = {en} }