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You searched for subject:(excrescence). Showing records 1 – 3 of 3 total matches.

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Texas A&M University

1. Crawford, Brian Keith. Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing.

Degree: 2015, Texas A&M University

Laminar flow has the potential to dramatically reduce fuel consumption and/or extend the range of modern aircraft. However, before laminar-flow aircraft can be made practical, the effect of surface imperfections must be better understood. Many studies have been performed on the effects of distributed roughness and other types of imperfections. Two-dimensional step excrescences, however have not been studied in significant detail until recently. Two-dimensional steps are common on real aircraft due to practical considerations such as skin-panel junctions, high-lift-device interfaces, deicing mechanisms, etc. Traditionally, these 2-D excrescences have been treated as just another form of roughness; however, the behavior of these steps is fundamentally distinct. The present study tests the effect of 2-D excrescences near 1% chord in order to examine the effects of pressure gradient and curvature. Testing on a 30? swept-wing model is performed in both the flight environment aboard a Cessna O-2A Skymaster, as well as in the Klebanoff-Saric Wind tunnel at Texas A&M University. In both environments, IR thermography is utilized to detect the global laminar?turbulent transition location. In the wind tunnel, a hotwire traverse is also utilized to map out the boundary layer and further measure the influence of these excrescences. Interactions between the crossflow instability and these excrescences are observed. Both critical and subcritical step induced transition behavior is present. Comparisons are made to other contemporary experiments in order to draw conclusions about the influence of pressure gradient, sweep, and curvature on the step-induced transition behavior. The resulting data are intended for use in validating an ongoing companion computational effort. Advisors/Committee Members: Saric, William S (advisor), Reed, Helen L (committee member), White, Edward B (committee member), Staack, David A (committee member).

Subjects/Keywords: laminar; transition; flight test; wind tunnel; excrescence; step; leading edge; transport aircraft

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Crawford, B. K. (2015). Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/154979

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Crawford, Brian Keith. “Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing.” 2015. Thesis, Texas A&M University. Accessed December 05, 2019. http://hdl.handle.net/1969.1/154979.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Crawford, Brian Keith. “Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing.” 2015. Web. 05 Dec 2019.

Vancouver:

Crawford BK. Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing. [Internet] [Thesis]. Texas A&M University; 2015. [cited 2019 Dec 05]. Available from: http://hdl.handle.net/1969.1/154979.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Crawford BK. Laminar-Turbulent Transition Due to 2-D Excrescences at 1% Chord on a Swept Wing. [Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/154979

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Hedderman, Simon Peter. Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition.

Degree: 2013, Texas A&M University

Skin friction drag reduction is one of the most promising paths in the investigation of the reduction of aircraft fuel burn. 40 ? 50% of overall drag comes from the surfaces of the wings and stabilizers. Natural laminar flow airfoils can extend the region of laminar flow and reduce skin friction drag. However, real-world aircraft wings do not have perfectly smooth surfaces, and therefore the tolerances for step and gap excrescences on these airfoils must be investigated. Previous work has focused on excrescences on flat plates, and only recently included pressure gradient effects. A new three-dimensional swept wing airfoil with an actuated leading edge (SWIFTER) has been constructed, and will extend the body of knowledge of step and gap excrescences to a more real-world configuration and higher Reynolds numbers. An integrated control system for the leading edge actuation system is proposed, including both interface hardware and control code. A heating system for the test surface is also discussed, and the controller hardware, sensors, and code specified. For wind tunnel testing, a proposed set of wall liners are developed from zero-lift condition streamlines and divided into parts suitable for manufacturing, assembly, and installation. Finally, preliminary wind tunnel step excrescence tests using an existing swept-wing model and applique step material were conducted, and the results are discussed with relevance to testing on the new model. Advisors/Committee Members: Saric, William S (advisor), Reed, Helen L (committee member), Bowersox, Rodney DW (committee member), Duggleby, Andrew T (committee member).

Subjects/Keywords: boundary layer; stability; excrescence; excrescences; SWIFT; SWIFTER; step; gap; airfoil; swept wing; actuation control system; heating sheet; wind tunnel; wall liners; natural laminar flow; nlf

excrescence height U∞ Freestream velocity VI Virtual Instrument β Pressure parameter β Model… …Angle of Attack/Aircraft Yaw Angle ν Kinematic viscosity νk Viscosity at excrescence… …23 Swept Wing In-Flight Testing Excrescence Research (SWIFTER) Model… …2 Figure 2 - Step excrescence tolerances (Drake et al., 2010)… …x29; .. 11 Figure 5 - Flat plate step excrescence study setup (Wang and Gaster, 2005… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hedderman, S. P. (2013). Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149269

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hedderman, Simon Peter. “Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition.” 2013. Thesis, Texas A&M University. Accessed December 05, 2019. http://hdl.handle.net/1969.1/149269.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hedderman, Simon Peter. “Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition.” 2013. Web. 05 Dec 2019.

Vancouver:

Hedderman SP. Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition. [Internet] [Thesis]. Texas A&M University; 2013. [cited 2019 Dec 05]. Available from: http://hdl.handle.net/1969.1/149269.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hedderman SP. Developments for a Swept Wing Airfoil to Study the Effects of Step and Gap Excrescences on Boundary Layer Transition. [Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149269

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Dos Santos Carvalho, Steve Francois. Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe.

Degree: Docteur es, Neurosciences, 2016, Bordeaux

La Polarité Cellulaire Planaire (PCP) est une voie de signalisation originellement identifiée chez les invertébrés pour son rôle dans l’établissement d’une asymétrie cellulaire perpendiculaire à l’axe apico‐basal. Elle définit une polarité dans le plan d’un épithélium et coordonne cette polarité dans tout l'épithélium. L'activation de la voie PCP conduit à une réorganisation ducyto squelette en passant par une modulation des zones d'adhésion, régulant ainsi la forme et les mouvements des cellules. La voie de signalisation de la PCP est conservée tout au long de l'évolution jusqu'au mammifères, et contrôle la morphogénèse de divers tissus dont les tissus épithéliaux et mésenchymateux, ainsi que pour les tissues cardiaques, osseux, pulmonaire ou encore rénaux, mais aussi le système nerveux pour n'en citer que quelques‐uns.Afin d'identifier le rôle de vangl2, un des gènes centraux de la PCP, dans la mise en place de la circuiterie hippocampale, nous avons créé un modèle murin où vangl2 est supprimé de façon conditionnelle (cKO) dans le télencéphale à des stades précoces de l’embryogénèse. J’ai d'abord montré que Vangl2 est enrichi dans les neurones immatures de la zone sous granulaire du DG, ainsi que dans l’arborisation des neurites (axones et dendrites) des cellules granulaires (CG) du gyrus denté (DG) de l’hippocampe. Ainsi, Vangl2 est enrichi dans le stratum lucidum (sl), une région dense en contacts synaptiques entre le DG et le CA3. Dans cette région a lieu une synapse très particulière entre l'axone des CG, la fibre moussue (Mf) qui forme des boutons géants (MfB) et les excroissances épineuse (TE) issues de la partie proximale des dendrites apicaux. L'analyse structurale et ultra structurale de ces épines démontre que l'élargissement et la complexification de la synapse MfB/TE est bloquée dans nos mutants, alors que les zones actives (PSD) des épines sont présentes, mais réorganisées. De façon intéressante,dans une zone plus distale des dendrites des neurones du CA3 (sl), les épines sont, elles, plus grosses, suggérant un remodelage complexe du réseau en l'absence de vangl2. Enfin, j’ai pu montrer que ces défauts morphologiques étaient corrélés à des problèmes de mémoire complexe (mémoire déclarative) qui dépendent de l’hippocampe mais aussi du cortex. Cette étude montre pour la première fois l’importance du signal PCP dans maturation in vivo d’un circuit hippocampique spécifique ainsi que ces conséquences cognitives. D'autres résultats in vitro montrent que la suppression de vangl2 augmente la vitesse de déplacement des cônes de croissance sur des substrats de N‐cadhérine. J’ai utilisé la microscopie en super résolution spt‐PALM‐TIRF pour montrer que cette augmentation de croissance est inversement proportionnelle à la vitesse du flux rétrograde d’actine. Des expériences de FRAP permettent de suggérer que les molécules de N‐cadhérine engagées dans des interactions hémophiliques (adhésion) est plus importante dans les mutants vangl2 Je propose que Vangl2 contrôle le recyclage et la stabilité des protéines… Advisors/Committee Members: Montcouquiol, Mireille (thesis director).

Subjects/Keywords: Polarité Cellulaire Planaire; Vangl2; N-cadhérine; Cône de croissance; Croissance neuronale; Adhésion; Flux rétrograde d’actine; Embrayage Moléculaire; Hippocampe; Gyrus Denté; CA3; Fibre Moussue; Bouton Fibre Moussue; Excroissance épineuse; PSD; Mémoire de Travail; Mémoire déclarative; Planar Cell Polarity; Vangl2; N-cadherin; Growth cone; Neuronal outgrowth; Adhesion; Actin Retrograde Flow; Molecular Clutch; Hippocampus; Dentate Gyrus; CA3; Mossy Fiber; Mossy Fiber Bouton; Thorny Excrescence; PSD; Working Memory; Declarative Memory

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dos Santos Carvalho, S. F. (2016). Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe. (Doctoral Dissertation). Bordeaux. Retrieved from http://www.theses.fr/2016BORD0276

Chicago Manual of Style (16th Edition):

Dos Santos Carvalho, Steve Francois. “Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe.” 2016. Doctoral Dissertation, Bordeaux. Accessed December 05, 2019. http://www.theses.fr/2016BORD0276.

MLA Handbook (7th Edition):

Dos Santos Carvalho, Steve Francois. “Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe.” 2016. Web. 05 Dec 2019.

Vancouver:

Dos Santos Carvalho SF. Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe. [Internet] [Doctoral dissertation]. Bordeaux; 2016. [cited 2019 Dec 05]. Available from: http://www.theses.fr/2016BORD0276.

Council of Science Editors:

Dos Santos Carvalho SF. Morpho-functional impact of Vangl2 on hippocampus development : Impact morpho-fonctionnel de Vangl2 sur le développement de l’hippocampe. [Doctoral Dissertation]. Bordeaux; 2016. Available from: http://www.theses.fr/2016BORD0276

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