자료유형  

 학위논문

Control Number  

0017164431

International Standard Book Number  

9798346394112

Dewey Decimal Classification Number  

330

Main Entry-Personal Name  

Hart, Pierce Luc.

Publication, Distribution, etc. (Imprint  

[S.l.] : The Pennsylvania State University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

235 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-05, Section: B.

General Note  

Advisor: Schmitz, Sven.

Dissertation Note  

Thesis (Ph.D.)--The Pennsylvania State University, 2024.

Summary, Etc.  

요약By its very nature, a capitalist economy creates pressure on industries to continuously pursue increased profit margins, and therefore reduced operational expenses. In the civil aviation sector, operational expenses are directly tied to fuel consumption, leading to significant research interest in improved efficiency of aircraft. While the development of new propulsion systems has been the primary contributor to decreased fuel burn, improved aerodynamics has also been a factor. In the last two decades, the financial incentives to reduce fuel burn have been accompanied by societal and governmental pressures to make aviation "more sustainable". Policies have been introduced to restrict air travel within France, and now Spain, introducing bans on short-haul flights. With fossil fuel prices and societal awareness at an all-time high, several roadmaps to de-carbonize aviation have been laid out by both regulatory bodies and industry leaders. As with efficiency improvements thus far, these outlines suggest that a more sustainable future will be dictated by propulsion, and more exactly the propellant. However, optimized aerodynamics will play an essential role in achieving the demands set out.There are several different approaches being considered to improve an aircraft's aerodynamic performance, yet they all share the same desired performance metric, that is a reduction in aerodynamic drag across the flight envelope. Proposed innovative redesigns that incorporate novel aerodynamic concepts come in two forms, whole-scale approaches such as the redefinition of commercial aircraft, i.e. the blended-wing body and the transonic truss-braced wing, or more modular considerations such as winglets, natural laminar-flow technology, boundary-layer ingestion, and distributed propulsion configurations, have all shown various levels of promise relative to the industry baseline.To make an adequate assessment of these technologies, an understanding of the phenomena creating the drag produced on the body is required. So, drag decomposition analysis is used, providing insight that allows one to better optimize the aerodynamics under consideration.Drag decomposition can be evaluated from two perspectives. A near-field decomposition evaluates the aerodynamic force acting over the skin of the aircraft, understood physically as normal or shear stress. The normal stress is attributed to the pressure distribution, while the shear stress is due to the skin friction. Alternatively, one may evaluate the drag in the far field using a momentum-based control-volume analysis. In far-field methods, data in the wake is used to decompose drag into its physiological sources: lift-induced drag associated with vortex shedding and profile drag which contains both wave drag due to shock-waves and viscous drag from the boundary layer. Using volumetric separation, it is theoretically possible to further decompose these drag sources entirely into viscous and wave drag. Because of their ability to decompose total drag into components associated with physiological sources, far-field methods have been preferred to a near-field stress analysis. Although they are informative, there are some inherent drawbacks of these methods. They are reliant on the assumption of lightly-loaded wings and have been derived for traditional aircraft where the nacelle is isolated from the aerodynamic body. New designs such as boundary-layer ingestion concepts have highly coupled propulsion systems, where it can also be difficult to distinguish the nacelle from the airframe. As such, these methods may become somewhat obsolete. Furthermore, the nature of far-field control-volume analyses means that the drag sources provided are single-value integrals, which means they provide limited feedback in the design process. These integrals are inherently difficult to solve in CFD as they require well-defined meshes both in the near field and the wake, which significantly increases the required computational resources. Appropriate implementation of far-field methods requires expert input to accurately capture each drag source.Due to these limiting factors, a near-field decomposition method is highly desirable. Therefore, the research objective of this thesis is to develop a near-field decomposition method relevant to commercial transport aircraft, a task that is undertaken through application of partial-pressure fields (PPFs). To successfully determine the feasibility of PPFs as an analysis tool in aircraft design. PPF theory is applied initially to two-dimensional airfoils in subsonic flow. Current theory allows one to split pressure into an Euler component associated with the bulk flow and a dissipative component accounting for the pressure created as a result of the viscous boundary layer. An evaluation of the drag factor of each PPF is made in subsonic flow. In transonic flow, there is an additional phenomenon to consider: shock formation. A PPF is developed to adequately capture the effects of the shockwave. Comparisons are made to state-of-the-art far-field decompositions to determine the validity of PPFs in such flow conditions. The final contribution of two-dimensional PPF analysis is the added consideration of thrust with a propulsive PPF generated to further our understanding of the impact of airframe/propulsor interactions.PPFs are extended to three-dimensional subsonic flows, introducing the consideration of induced drag, an inertial effect captured by the Euler PPF. The ONERA M6 wing is used as an initial case study in subsonic flow because of its simple geometry. Comparisons of the Euler PPF are made to an inviscid polar with viscous simulation undertaken at two Reynolds numbers, allowing for an investigation into the viscous-inviscid interaction and its impact on PPF drag book-keeping. The wing polar is analyzed in both subsonic and transonic flow where the PPF results are compared to classical far-field methods. Additional perspective is gained through the subsonic analysis of the Ventus-3 sailplane wing. This case study provides an industrial geometry to demonstrate real-world applicability and potential usefulness of the developed theory. The subsonic nature of sailplane aerodynamics means that a comparison between the Euler drag and far-field induced drag can be made, thus providing further insight as to the nature of viscous-inviscid interactions. Furthermore, the high aspect ratio wing means that classical lifting-line theory may also be used to estimate the induced drag, providing an effective comparison of three different decomposition tools.New challenges are introduced when considering transonic three-dimensional flows. In such cases, the profile drag contains both the wave and viscous drag, while the Euler drag includes the wave and induced components. To avoid using volumetric decompositions, a novel method to determine wave drag was considered, using a hybrid near-field and far-field approach. This method was applied to the ONERA M6 wing and the NASA Common Research Model under conditions conducive to drag formation for each of the three sources associated with a commercial transport aircraft in cruise. Through comparison of the latter study to previous far-field investigations, additional insight is gained making it apparent that this wave drag method includes an interactive drag source, leading to the wave drag prediction being higher than that of methods using the volumetric-based alternative. An attempt to overcome issues associated with the hybrid approach are made through the development of an entirely near-field decomposition method, which uses classical aerodynamic theory. The method is applied to the ONERA M6 wing and shows good agreement with far-field data from another study.The results of various simulations indicate that PPFs may be highly useful in the future of aircraft design. They can be used to provide further insight as to the sources of drag on an aircraft, whether they are used independently or in tandem with far-field methods. PPFs overcome some of the difficulties associated with far-field methods, as they provide an entire scalar field for data visualization while removing the requirement for a highly-refined wake. PPFs avoid issues with the separation of profile drag and provide separability of thrust and drag sources allowing for meaningful thrust/drag book-keeping using momentum-based CFD analyses.

Subject Added Entry-Topical Term  

Aircraft.

Subject Added Entry-Topical Term  

Decomposition.

Subject Added Entry-Topical Term  

Pressure distribution.

Subject Added Entry-Topical Term  

Reynolds number.

Subject Added Entry-Topical Term  

Boundary conditions.

Subject Added Entry-Topical Term  

Fluid mechanics.

Subject Added Entry-Topical Term  

Mathematics.

Added Entry-Corporate Name  

The Pennsylvania State University.

Host Item Entry  

Dissertations Abstracts International. 86-05B.

Electronic Location and Access  

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Control Number  

joongbu:656960