Person:
Mavris, Dimitri N.

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Now showing 1 - 7 of 7
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    A Method for Probabilistic Sensitivity Analysis of Commercial Aircraft Engines
    (Georgia Institute of Technology, 1999-09) Mavris, Dimitri N. ; Roth, Bryce Alexander ; Macsotai, Noel I.
    The objective of this paper is to illustrate how probabilistic methods can be utilized to rationally and analytically make design decisions in the presence of uncertainty, with emphasis on the use of probabilistic sensitivities in the aircraft gas turbine engine preliminary design process. A brief review of risk and uncertainty in the engine design process is given, and the role of probabilistic methods is discussed. Probabilistic sensitivity analysis, used in conjunction with response surface methods, is proposed as a computationally-efficient method to address defined sources of uncertainty and risk in engine design from a system level perspective. The method outlined is then applied to the analysis of engine component performance uncertainty impact on the performance of a notional four-engine wide-body commercial transport. More specifically, uncertainty in engine design parameters is shown to have a direct and quantifiable impact on aircraft system figures of merit such as design range and fuel burn. The methods developed are then used to create a set of contour plots showing the behavior of vehicle performance uncertainty over the design space of interest.
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    Analysis of Advanced Technology Impact on HSCT Engine Cycle Performance
    (Georgia Institute of Technology, 1999-06) Roth, Bryce Alexander ; Mavris, Dimitri N.
    The objective of this paper is to describe and apply methods that could assist the propulsion system designer in the evaluation and selection of propulsion technologies. The focus here is on the aerothermo-dynamic aspects of the problem, particularly estimation of engine internal losses. This is accomplished by leveraging developments in second law analysis methods that are able to quantify the theoretical work potential as well as the loss in work potential. Two basic methods, exergy and suitability of each for propulsion systems analysis is discussed. These are used to develop a simple approach to engine internal loss estimation, and are then demonstrated on several basic technology scenarios for a High Speed Civil Transport Propulsion System. The various sources of loss for each concept are examined in detail, and the results for the two methods are compared.
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    Additional development and systems analyses of pneumatic technology for high speed civil transport aircraft
    (Georgia Institute of Technology, 1999) Willie, F. Scott ; Lee, Warren J. ; Niebur, Curt S. ; Gregory, Scott D. ; Mavris, Dimitri N. ; Tai, Jimmy C. M. ; Kirby, Michelle Rene ; Roth, Bryce Alexander ; Engler, R. J. (Robert J.)
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    A Stochastic Approach to Designing Affordable, Environmentally Acceptable Systems
    (Georgia Institute of Technology, 1999-01) Mavris, Dimitri N. ; Roth, Bryce Alexander
    The focus of the work being conducted under this grant is to create a virtual stochastic l environment that will enable designers to make decisions in the presence of uncertainty while considering all aspects relevant to the design at the earliest possible time. This paper describes a portion of this research involving the application of a probabilistic method which allows designers to make direct trades between probability of meeting design goals and product performance (such as specific fuel consumption). The example described here is focused on the cycle selection for a notional commercial aircraft engine such that the design merit can be quantified in terms of a probability of meeting a design target. Ultimately, this research will be extended to include environmental aspects such as acoustic noise and emissions requirements.
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    A Probabilistic Design Methodology for Commercial Aircraft Engine Cycle Selection
    (Georgia Institute of Technology, 1998-09) Mavris, Dimitri N. ; Macsotai, Noel I. ; Roth, Bryce Alexander
    The objective of this paper is to examine ways in which to implement probabilistic design methods in the aircraft engine preliminary design process. Specifically, the focus is on analytically determining the impact of uncertainty in engine component performance on the overall performance of a notional large commercial transport, particularly the impact on design range, fuel burn, and engine weight. The emphasis is twofold: first is to find ways to reduce the impact of this uncertainty through appropriate engine cycle selections, and second is on finding ways to leverage existing design margin to squeeze more performance out of current technology. One of the fundamental results shown herein is that uncertainty in component performance has a significant impact on the overall aircraft performance (it is on t he same order of magnitude as the impact of the cycle itself). However, this paper shows that uncertainties in component efficiencies, pressure losses, and cooling flow losses do not have a significant influence on the variance of aircraft performance. This paper also shows that the probabilistic method is very useful for formulating direct trades of design margin against performance or other figures of merit such as engine weight, thus enabling the existing design margin to be capitalized upon in the interest of obtaining better system performance. In terms of a comparison between techniques, one can conclude that the probabilistic approach is inherently more computationally intensive that the deterministic approach. It therefore behooves the designer to choose wisely when setting up the problem in order to avoid unnecessary work. However, a properly formulated probabilistic method provides a much clearer picture of how the various system trades another and enables the ultimate cycle selection to be analytically determined based on the level of risk that is consistent with program objectives.
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    A Probabilistic Approach to UCAV Engine Sizing
    (Georgia Institute of Technology, 1998-07) Roth, Bryce Alexander ; Mavris, Dimitri N. ; Elliott, Don
    This paper describes a probabilistic approach to aircraft engine thrust sizing which is intended to assist the designer in making decisions during the very early stages of the design process when the operational concept is still evolving and uncertainty abounds (in both mission requirements and technological capability). The focus of this paper is on analysis of mission uncertainty such as that due to ambiguity in payload, range, maneuver requirements, etc. and its impact on propulsion system sizing. Several analysis tools appropriate for probabilistic thrust sizing are discussed and one is applied to the probabilistic thrust sizing of an unmanned combat aerial vehicle designed for a deep-strike mission. The result is a distribution for thrust which can then be used in combination with the core engine design space to estimate the design? probability of successfully meeting the thrust requirements. Finally, a method for tracking mission uncertainty as the requirements develop is described and illustrated for the UCAV example.
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    A Methodology for Robust Design of Impingement Cooled HSCT Combustion Liners
    (Georgia Institute of Technology, 1997-01) Mavris, Dimitri N. ; Roth, Bryce Alexander
    This paper describes the use of a robust design simulation methodology for the determination of an optimum lean, premixed, prevaporized combustor liner cooling configuration for a High Speed Civil Transport. The objective of design robustness as developed at the Georgia Institute of Technology is to find settings for design parameters which will not only maximize performance, but also minimize the influence of uncertainty on performance. This robust design simulation methodology is formulated here as a very general approach that lends itself to any design problem where uncertainty exists. This general methodology is applied to the design of a combustor liner in order to quantify the effect of cycle parameter and heat transfer coefficient uncertainties on combustor liner metal temperature variance. The results show that for the parameter ranges of interest, impingement hole spacing and thermal barrier coating thickness have the greatest effect on metal temperature variance and are used to find a robust liner configuration.