In recent years, there has been a growing shift in the world towards sustainability. For civil aviation, this is reflected in the goals of several organizations including NASA and ACARE as significantly increased fuel efficiency along with reduced harmful emissions in the atmosphere. Achieving the goals necessitates the advent of novel and radical aircraft technologies, NASA's X-57, is one such concept using distributed electric propulsion (DEP) technology.
Although practical implementation of DEP is achievable due to the scale invariance of highly efficient electric motors, the current battery technology restricts its adoption for commercial transport aircraft. A Hybrid Electric Distributed Propulsion (HEDiP) system offers a promising alternative to the all-electric system. It leverages the benefits of DEP when coupled with a hybrid electric system. One of the areas needing improvement in HEDiP aircraft design is the fast and accurate estimation of wing aerodynamic characteristics in the presence of multiple propellers. A VLM based estimation technique was developed to address this requirement.
This research is primarily motivated by the need to have mature conceptual design methods for HEDiP aircraft. Therefore, the overall research objective is to develop an effective conceptual design capability based on a proven multidisciplinary design optimization (MDO) framework, and to demonstrate the resulting capability by applying it to the conceptual design of a regional transport aircraft (RTA) with HEDiP systems. / Master of Science / Recent years have seen a growing movement to steer the world towards sustainability. For civil aviation, this is reflected in the goals of key organizations, such as NASA and ACARE, to significantly improve fuel efficiency, reduce harmful emissions, and decrease direct heat release in the atmosphere. Achieving such goals requires novel technologies along with radical aircraft concepts driven by efficiency maximization as well as using energy sources other than fossil fuel. NASA’s all-electric X-57 is one such concept using the Distributed Electric Propulsion (DEP) technology with multiple electric motors and propellers placed on the wing. However, today’s all-electric aircraft suffer from the heavy weight penalty associated with batteries to power electric motors. In the near term, a Hybrid Electric Distributed Propulsion (HEDiP) system offers a promising alternative. HEDiP combines distributed propulsion (DiP) technology powered by a mix of two energy sources, battery and fossil fuel. The overall goal of the present study is to investigate potential benefits of HEDiP systems for the design of optimal regional transport aircraft (RTA).
To perform this study, the aerodynamics module of the Pacelab Aircraft Preliminary Design (APD) software system was modified to account for changes in wing aerodynamics due to the interaction with multiple propellers. This required the development of the Wing Aerodynamic Simulation with Propeller Effects (WASPE) code. In addition, a Wing Propeller Configuration Optimization (WIPCO) code was developed to optimize the placement of propellers based on location, number, and direction of rotation. The updated APD was applied to develop the HERMiT 2E series of RTA. The results demonstrated the anticipated benefits of HEDiP technologies over conventional aircraft, and provided a better understanding of the sensitivity of RTA designs to battery technology and level of hybridization, i.e., power split between batteries and fossil fuels. The HERMiT 6E/I was then designed to quantify the benefits of HEDiP systems over a baseline Twin Otter aircraft. The results showed that a comparable performance could be obtained with more than 50% saving in mission energy costs for a small weight penalty. The HERMiT 6E/I also requires only about 38% of the mission fuel borne by the baseline. This means a correspondingly lower direct atmospheric heat release, reduction in carbon dioxide and NOx emissions along with reduced energy consumptions.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/84494 |
| Date | 03 August 2018 |
| Creators | Rajkumar, Vishnu Ganesh |
| Contributors | Aerospace and Ocean Engineering, Raj, Pradeep, Choi, Seongim Sarah, Allison, Darcy L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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