Aeronautical engineering: A continuing bibliography with indexes (supplement 232)

This bibliography lists 422 reports, articles, and other documents introduced into the NASA scientific and technical information system in October, 1988

A Modular and Integrated Optimisation Model for Underwater Vehicles

A modular and integrated optimisation model for the design of underwater vehicles is presented. In the proposed optimisation model two modules (i.e. low fidelity and high fidelity) are incorporated and the basic geometric definition of computer aided design (CAD) is integrated with computational fluid dynamic (CFD) analysis. The hydrodynamic drag is considered as single objective with constraints on the geometric parameters of dimension, space and volume. The CAD model is implemented in MATLAB*TM and CFD model is implemented in Shipflow**TM. A real-world design example of an existing underwater vehicles is presented. The applicability of proposed optimisation model is shown. The presented results show that within given set or sets of constraints the application of optimisation model in design results into an efficient hull form.

Aeronautical engineering: A continuing bibliography with indexes (supplement 296)

This bibliography lists 592 reports, articles, and other documents introduced into the NASA scientific and technical information system in Oct. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Bending moment and efficient fatigue assessment in a Subsea Shuttle Tanker under the effect of waves

The subsea shuttle tanker (SST) is the next-generation autonomous submarine designed to transport liquid CO2 from land/offshore facilities to the smaller fields for injection. Unlike normal shuttle tankers, which are highly weather dependent, the SST can carry out freight operations in all weather conditions because it travels underwater between 40 m and 70 m water depth. The first part of the thesis proposes a fast, efficient and reliable multi-body approach to determine the bending moment response of the SST hull at 40 m and 70 m water depth. The chosen approach is based on the discrete-module-beam bending-based hydroelasticity principle. The flexible hull of the vessel is divided into several multi-body rigid modules. All the hydrodynamic and hydrostatic forces are applied to the center of gravity of each rigid module. The parametric models, like the state-space model system, are used to compute the free-surface memory effect more effectively. The multi-body equation of motion is solved to determines the bending moment response of an interconnected multi-body rigid module. The numerical model is prepared using Matlab Simulink to study the dynamics of the vessel. A convergence study is conducted to select the optimal number of bodies needed to perform this study. The result shows that the lower number of bodies (i.e., three and five bodies) does not have enough points to capture all the wave encounter frequencies, thus underestimating the bending moment. Therefore, seven-body SST is used to carry out a further assessment. The bending moment standard deviation is reduced by approximately 50 % when SST travels at 70 m water depth instead of 40 m. The second part of the thesis presents the fatigue assessment of the SST hull, considering the stiffeners' local details. Two FE models (2D axisymmetric and 3D shell element models) representing the local detail of the flooded-mid body of the SST are prepared to determine the stress concentration factor (SCF). The resultant SCF can be given using the superposition concept by taking the product of the SCF for the individual models. The Rainflow counting method and Palmgren-Miner rule are used to calculate the accumulated fatigue damage and fatigue life. The numerical results show that the impact of long waves has contributed to the most damage to the vessel. The minimum fatigue life at the flooded-mid section is 13 and 19 years for the 40 m and 70 m water depths, respectively. The results also shows that fatigue life due to the change in hydrostatic pressure during dive-in and dive-out is five years

Rapid Prediction of Low-Boom and Aerodynamic Performance of Supersonic Transport Aircraft Using Panel Methods

The Utah State University Aerolab developed and tested a set of tools for rapid prediction of the loudness of a sonic boom generated by supersonic transport aircraft. This work supported a larger effort led by Texas A&M to investigate the use of adaptive aerostructures in lowering sonic boom loudness at off design conditions. Successful completion of this effort will improve the feasibility of supersonic commercial transport over land. Funding was provided by a NASA University Leadership Initiative grant to several universities, including Utah State University, as well as industry partners to complete this work over a five year period. The work presented in this thesis was done over the first year of the grant. The Aerolab team was specifically tasked with developing a set of tools for rapidly predicting the sonic boom loudness of supersonic aircraft. Specifically, this work included an assessment of the existing analysis tools available followed by the planning, development, and testing of a framework of tools for performing the needed calculations. Results of the framework were compared against high fidelity solutions available from the 2017 AIAA Sonic Boom Prediction Workshop. These comparisons revealed that panel methods perform well for simple geometries. However, localized errors appear when modeling more complex geometries that reduce the accuracy of the predicted sonic boom loudness. It was found that these localized errors were a consequence of the inherent assumptions built into panel methods. Consequently, in future work, it may be necessary to develop techniques for combining the results of panel methods with higher fidelity methods or to revisit the panel method formulation

Aeronautical engineering: A continuing bibliography with indexes (supplement 193)

This bibliography lists 682 reports, articles and other documents introduced into the NASA scientific and technical information system in October 1985

Aeronautical Engineering: A special bibliography with indexes, supplement 54

This bibliography lists 316 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1975

Aeronautical engineering: A continuing bibliography with indexes (supplement 218)

This bibliography lists 469 reports, articles, and other documents introduced into the NASA scientific and technical information system in September, 1987