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In the development of modern rotorcraft vehicles, many unique challenges emerge due to the highly coupled nature of individual rotorcraft design disciplines therefore, the use of an integrated product and process development (IPPD) methodology is necessary to drive the design solution. Through the use of parallel design and analysis, this approach achieves the design synthesis of numerous product and process requirements that is essential in ultimately satisfying the customers demands. Over the past twenty years, Georgia Techs Center for Excellence in Rotorcraft Technology (CERT) has continuously focused on refining this IPPD approach within its rotorcraft design course by using the annual American Helicopter Society (AHS) Student Design Competition as the design requirement catalyst. Despite this extensive experience, however, the documentation of this preliminary rotorcraft design approach has become out of date or insufficient in addressing a modern IPPD methodology. In no design discipline is this need for updated documentation more prevalent than in propulsion system design, specifically in the area of gas turbine technology. From an academic perspective, the vast majority of current propulsion system design resources are focused on fixed-wing applications with very limited reference to the use of turboshaft engines. Additionally, most rotorcraft design resources are centered on aerodynamic considerations and largely overlook propulsion system integration. This research effort is aimed at bridging this information gap by developing a preliminary turboshaft engine design methodology that is applicable to a wide range of potential rotorcraft propulsion system design problems. The preliminary engine design process begins by defining the design space through analysis of the initial performance and mission requirements dictated in a given request for proposal (RFP). Engine cycle selection is then completed using tools such as GasTurb and the NASA Engine Performance Program (NEPP) to conduct thorough parametric and engine performance analysis. Basic engine component design considerations are highlighted to facilitate configuration trade studies and to generate more detailed engine performance and geometric data. Throughout this approach, a comprehensive engine design case study is incorporated based on a two-place, turbine training helicopter known as the Georgia Tech Generic Helicopter (GTGH). This example serves as a consistent propulsion system design reference highlighting the level of integration and detail required for each step of the preliminary turboshaft engine design methodology.

Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Seitzman, Jerry; Committee Member: Filatyev, Sergei; Committee Member: Jagoda, Jechiel; Committee Member: Lieuwen, Timothy; Committee Member: Shelton, Samuel; Committee Member: Zinn, Ben. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This paper presents an analysis of the potential of Micro Gas Turbines (MGT) with regards to performance, economic and durability considerations. The performance potential was assessed by calculating the cycle efficiency based on the Brayton cycle and the mechanical efficiency of the expansion turbine. The economic potential was evaluated by calculating the specific fuel consumption and estimating the cost and manufacturability of the turbine components. The durability and reliability of the components were assessed by considering the effects of transient thermal stresses and unstable ignition. The results indicated that ceramic materials can achieve a 63% increase in efficiency over nickel-based alloys and a 39% reduction in specific fuel consumption. It was also found that the grinding process on the metal-ceramic shaft connection is the most expensive as it relies on diamond grinding, while ceramic turbines can have an initial procurement cost advantage whenproduced in higher volumes. Finally, it was found that ceramic materials are less reliable due to their higher hardness and sensitivity to pressure spikes, and therefore require careful consideration when designing the components. / I detta dokument presenteras en analys av potentialen hos mikrogasturbiner (MGT) med avseende på prestanda, ekonomi och hållbarhet. Prestandapotentialen bedömdes genom att beräkna cykelns effektivitet baserad på Braytoncykeln och expansionsturbinens mekaniska effektivitet. Den ekonomiska potentialen utvärderades genom att beräkna den specifika bränsleförbrukningen och uppskatta kostnaden och tillverkningsbarheten för turbinkomponenterna. Komponenternas hållbarhet och tillförlitlighet bedömdes genom att man beaktade effekterna av tillfälliga termiska påfrestningar och instabil tändning. Resultaten visade att keramiska material kan öka effektiviteten med 63% jämfört med nickelbaserade legeringar och minskaden specifika bränsleförbrukningen med 39%. Det konstaterades också att slipningen av axelförbindelsen mellan metall och keramik är den dyraste eftersom den bygger på diamantslipning, medan keramiska turbiner kan ha en kostnadsfördel vid den första anskaffningen när de tillverkas i större volymer. Slutligen konstaterades det att keramiska material är mindre tillförlitliga på grund av deras högre hårdhet och känslighet för tryckspikar, och att det därför krävs noggranna överväganden vid utformningen av komponenterna.

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Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study is an introductory investigation into vaporizer technology as implemented in micro gas turbines. Experimental investigations are aimed at the development of expectations concerning the internal flow structure though vaporizers by generating application specific flow maps. Consolidation of these maps with other experimental data suggests that annular flow leads to increased evaporation rates. In addition, it was discovered that flow structure is affected by the injection angle and air and fuel flow rates. An investigation into the numerical modelling of vaporizers is based on two phase flow theory using a flow structure approach. The numerical behaviour is observed for parametric variations to establish the impact of assumptions. A final numerical model is formulated with empirically determined coefficients with fair correlation to experimental data. The results of this study yield recommendations towards the implementation and analysis of vaporizers with applied use in micro gas turbines. / AFRIKAANSE OPSOMMING: Hierdie studie is 'n inleidende ondersoek na verdamper tegnologie soos toegepas in mikro gasturbines. Eksperimentele ondersoeke is gerig op die ontwikkeling van kennis rakende die interne vloeistrukture deur verdampers met die bou van toepassingspesifieke vloeikaarte. Konsolidering van hierdie kaarte met verdere eksperimentele data dui daarop dat annulêre vloei lei tot verhoogde verdampingstempo’s. Daar is ook bevestig dat die vloei struktuur deur die inspuitingshoek en vloeitempo’s affekteer word. 'n Ondersoek na die numeriese modellering van verdampers is gebasseer op twee-fase vloei met 'n vloeistruktuur benadering. Die numeriese gedrag is waargeneem vir parametriese variasies om sodoende die impak van aannames te bevestig. Die numeriese model is voltooi met empiriese bepaalde koëffisiënte en lei tot goeie korrelasie met eksperimentele data. Resultate van hierdie studie lei tot aanbevelings rakende die implementering en ontleding van verdampers met spesifieke toepassing op mikro gas turbines.

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