http://smartech.gatech.edu/handle/1853/6027 The Aerospace Systems Design Laboratory was founded in 1992 and has grown to be one of the nation’s premier centers for the development and application of advanced design methods for complex systems, and the training of the next generation engineers and scientists. Search the Channel search http://smartech.gatech.edu/simple-search http://smartech.gatech.edu/handle/1853/10738 Title: Sonic Boom Minimization Using Improved Linearized Tools and Probabilistic Propagation <br/> <br/>Authors: Rallabhandi, Sriram Kishore; Mavris, Dimitri N. <br/> <br/>Abstract: Sonic boom modelling is multidisciplinary involving aerodynamic and aero-acoustics analyses. The near field pressure signature is first obtained using either linearized or non-linear methods. This is then converted into a F-function, which is then propagated to the ground using aero-acoustic routines. Existing linearized methods operate on simple approximations of true geometry. Using improved linearized tools that operate on unstructured water-tight geometries, the accuracy and efficacy of shape optimization can be greatly improved. The sonic boom minimization technique is reformulated as an optimization problem and boom propagation is carried out in a probabilistic fashion. A bi-level reverse optimization is conducted to design aircraft to meet low sonic boom requirements under atmospheric uncertainty. <br/> <br/>Description: Presented at the 43rd Aerospace Sciences Meeting and Exhibit, Reno NV, Jan 10-13, 2005 Thu, 09 Jun 2005 22:58:59 GMT http://smartech.gatech.edu/handle/1853/10737 Title: Power Based Sizing Method for Aircraft Consuming Unconventional Energy <br/> <br/>Authors: Nam, Taewoo; Soban, Danielle Suzanne; Mavris, Dimitri N. <br/> <br/>Abstract: Traditionally, most fixed wing and rotary wing aircraft have been powered by internal combustion engines that consume hydrocarbon fuels. Only in a few exceptional designs, such as solar powered air-vehicles, are attempts made to apply alternate energy sources. In the past decade, however, the aerospace community has shown a renewed interest in alternate energy sources for revolutionary propulsion systems. In particular, fuel cells are increasingly being considered as an alternate power source for their potential outstanding advantages over the traditional power system. Nevertheless, traditional aircraft sizing methods are not immediately applicable for such unconventional-energy consuming air-vehicle designs. This paper proposes a generalized aircraft sizing formulation that is also applicable to revolutionary aircraft concepts powered by unconventional energy sources and/or have revolutionary propulsion systems. A power based formulation, which allows easy tracking of energy transformation process from the first power generation to the last propulsive power production, is introduced. Lastly, a generalized aircraft weight estimation formulation that is also valid for unconventional-energy consuming propulsion systems is developed. <br/> <br/>Description: Presented at the 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan. 10-13, 2005. Sun, 09 Jan 2005 22:58:59 GMT http://smartech.gatech.edu/handle/1853/10610 Title: Probabilistic Matching of Turbofan Engine Performance Models to Test Data <br/> <br/>Authors: Roth, Bryce Alexander; Doel, David L.; Cissell, Jeffrey J. <br/> <br/>Abstract: This paper describes the development of an improved method for reliable, repeatable, and accurate matching of engine performance models to test data. The centerpiece of this approach is a minimum variance estimator algorithm with a priori estimates which addresses both deterministic and probabilistic aspects of the problem. Specific probabilistic aspects include uncertainty in the measurements, prior expectations on model matching parameters, and noise in the power setting parameters. The algorithm is able to produce optimal results using any number of measurements and model matching parameters and can therefore take advantage of all measured data to produce the best possible match. This improves on current matching algorithms which require that the number of measured parameters be equal to the number of model matching parameters. This algorithm has been implemented in the Numerical Propulsion System Simulation (NPSS) and tested on a generic high-bypass turbofan model typical of those used in commercial service. The baseline engine model and simulated test data are described in detail. Several exercises are discussed to illustrate results available from this algorithm including the matching of a typical power calibration data set and matching of a typical production engine data set. <br/> <br/>Description: Proceedings of ASME Turbo Expo 2005: Land Sea & Air, June 6-9, 2005, Reno-Tahoe. Sun, 05 Jun 2005 22:58:59 GMT http://smartech.gatech.edu/handle/1853/10606 Title: Lost Thrust Methodology for Gas Turbine Engine Performance Analysis <br/> <br/>Authors: Roth, Bryce Alexander; De Luis, Jorge <br/> <br/>Abstract: This paper presents and evaluates a lost thrust method for analysis of thermodynamic performance in gas turbine engines. This method is based on the definition of a hypothetical ideal engine that is used as a point of comparison to evaluate performance of the real engine. Specifically, component loss is quantified in terms of decrements in thrust of the real engine relative to the ideal engine having the same design point cycle. These lost thrust decrements provide a basis for accurately evaluating the performance cost of component losses while simultaneously accounting for all component interactions. The analysis algorithm is formally developed in detail and is then demonstrated for a typical separate flow turbofan engine. Various scenarios are examined and the results of these exercises are used to draw conclusions regarding the strengths and weaknesses of this approach to gas turbine performance analysis. <br/> <br/>Description: Proceedings of GT2005: ASME Turbo Expo2005: Land, Sea and Air, June 6-9, 2005, Reno-Tahoe Sun, 05 Jun 2005 22:58:59 GMT