The design process and construction of the initial modular ramjet attachment to the Cal Poly supersonic wind tunnel is presented. The design of a modular inlet, combustor, and nozzle are studied in depth with the intentions of testing in the modular ramjet. The efforts undertaken to characterize the Cal Poly supersonic wind tunnel and the individual component testing of this attachment are also discussed. The data gathered will be used as a base model for future expansion of the ramjet facility and eventual hot fire testing of the initial components. Modularity of the inlet, combustion chamber, and nozzle will allow for easier modification of the initial design and the designs ability to incorporate clear walls will allow for flow and combustion visualization once the performance of the hot flow ramjet is determined. The testing of the blank ramjet duct resulted in an error of less than 10% from predicted results. The duct was also tested with the modular inlet installed and resulted in between a 13-30% error based on the predicted results. Hot flow characteristics of the ramjet were not achieved, and the final cold flow test with the nozzle installed was a failure due to improper configuration of the nozzle. The errors associated with this testing can largely be placed on the poor performance of the Cal Poly supersonic wind tunnel and the alterations made to the testing in an attempt to accommodate these flaws. The final tests were halted for safety concerns and could continue after a thorough safety review.

The main scope of this project was to determine if a plasma torch could operate on pure hydrocarbon feedstocks and, if so, to catalogue the torch operational characteristics. The future goal of the project is to design a plasma torch for supersonic combustion applications that operates off of the vehicle main fuel supply to simplify onboard fuel systems. Experiments were conducted with argon, methane, ethylene and propylene. Spectrographic tests and tests designed to catalogue current/voltage characteristics, plasma jet phenomena, arc stability dependencies, electrode erosion rate and torch body temperature were performed. Spectrographic analysis of the plasma jet exhaust confirmed the presence of combustion-enhancing radicals for each hydrocarbon gas tested. Also, it was discovered that simple hydrocarbon gases, such as methane, produced smooth torch operation, while even slightly more complex gases, ethylene and propylene, caused unsteady performance. Plasma jet oscillation was found to be related to the voltage waveform of the power supplies, indicating that plasma jet length and oscillation rate could be controlled by changing the input voltage. The plasma torch for this study was proven to have the capability of operating with pure hydrocarbon feedstocks and producing radicals that are known to reduce combustion reaction rate times. The torch was demonstrated to have potential for use in supersonic combustion applications. / Master of Science

The present work was conducted with the intent of developing a high-fidelity numerical model of a unique combustion flow problem combining multi-phase fuel injection with substantial momentum and temperature into a highly complex turbulent flow. This important problem is very different from typical and more widely known liquid fuel combustion problems and is found in practice in pulverized coal combustors and ducted rocket ramjets. As the ducted rocket engine cycle is only now finding widespread use, it has received little research attention and was selected as a representative problem for this research. Prior to this work, a method was lacking domestically and internationally to effectively model the ducted rocket engine cycle with confidence. In the ducted rocket a solid fuel gas generator is used to deliver a fuel-rich multi-phase mixture to the combustion chamber. When a valve is used to vary the fuel generator pressure, and thereby the delivered fuel flowrate, the engine is known as a Variable Flow Ducted Rocket (VFDR). The Aerojet MARC-R282 ramjet engine represents the worlds first VFDR flown, and the first in operational use. Although performance requirements were met, improvements are sought in the understanding of the ramjet combustion process with a future aim of reducing the visible exhaust and correcting uneven combustor heating patterns. For this reason the MARC-R282 combustor was selected as the baseline geometry for the present research, serving to provide a documented baseline case for numerical modeling and also being a good candidate to benefit from an improved understanding of the combustion process. In order to proceed with the present research, experiments were first carried out to characterize the gas generator particulate exhaust in terms of composition and particle size. Equilibrium thermochemistry was used to supplement these data to develop a gas phase combustion model. The gas phase reactions and resulting particle definition were modeling using the FLUENT Computational Fluid Dynamics (CFD) code for the baseline GQM-163A Supersonic Sea Skimming Missile (SSST) operating conditions. These results were compared to direct-connect ramjet ground tests in order to validate the analysis tool. Data were developed to understand the gas and solid phase fuel exhaust characteristics at the propellant surface, exiting the gas generator injector, and following secondary combustion with air. Particles were collected and analyzed from the fuel generator exhaust. While exhibiting some variation with time in the firing, they were roughly an average of 20 microns in diameter, in line with prior experience with pulverized coal combustion experiments. A computational model was developed based on coal combustion parameters using FLUENT. However, despite considerable effort, the CFD analysis was not able to predict effective burning of the carbon particles to the degree seen in testing. In addition, using equilibrium thermochemistry as a basis for determining the carbon particle content in the fuel exhaust, the CFD analysis resulted in trends in performance opposite to the test results. These facts led to a hypothesis that there was actually a significant fraction of small particles or much less carbon produced than equilibrium thermochemistry would predict. A parametric analysis was performed replacing the 20 micron soot particles with fine fraction particles, representing a fraction of the predicted equilibrium carbon soot being still in the gas phase as higher molecular weight hydrocarbons, or in the form of sub-micron particles. When almost all particles were replaced with fine fraction particles, the model was able to correctly predict absolute values of combustion efficiency as well as trends for different injector geometries. The presence of particles was apparent from the visible exhaust and collection data, however they were found not to play a significant role in the combustion process for this fuel and engine configuration. The robustness of the computational model was also evaluated by examining the effects of turbulence model, order of discretization, and grid size. Comparable trends and results were seen for all cases examined. With the successful development of this modeling tool and an improved understanding of the combustion process, future work is enabled to develop improved combustor flow management and fuel injection schemes to improve existing designs and develop new configurations. This research has served to advance the field of combustion modeling by providing: 1) a solid ducted rocket combustion modeling tool considering solid and gas phase combustion, 2) a correlation between primary combustion theory and particulate exhaust sampling, 3) low length/diameter ratio ducted rocket combustor modeling, and 4) combustor CFD coupled with solid particle tracking and combustion models. / Ph. D.

Approved for public release, distribution is unlimited / Methods used for designing the ramjet included conic shock tables; isentropic flow tables and the GASTURB code was used for aerothermodynamic performance prediction. The flow field through the proposed geometry was computed using the OVERFLOW code, and small modifications were made. Geometry and solid models were created and built using SolidWorks 3D solid modeling software. A prototype ramjet was manufactured with wind tunnel mounting struts capable of measuring axial force on the model. Shadowgraph photography was used in the Mach 4 supersonic wind tunnel at the Naval Postgraduate School's Turbopropulsion Laboratory to verify predicted shock placement, and surface flow visualization was obtained of the airflow from fuel injection ports on the inlet cone of the model. All indications are that the cold-flow tests were successful. / Ensign, United States Naval Reserve

La demande pour les ressources énergétiques est en hausse alors que leur disponibilité est en baisse. Dans ce contexte, l’industrie du transport et de l’énergie est à la recherche de petits moteurs efficaces et puissants et le Rim Rotor Rotary Ramjet Engine (R4E) pourrait correspondre à ces critères. Or, en ce moment, le potentiel de ce moteur est limité, car son compresseur supersonique entraîne des pertes d’efficacité lorsque le rotor tourne à son nombre de Mach tangentiel optimal qui est de 2. Le présent mémoire compile toutes les notions requises pour comprendre le fonctionnement d’un compresseur supersonique lors de son démarrage et de concevoir le compresseur le plus approprié pour le R4E, tant en démarrage qu’en régime permanent. Pour se faire, des concepts de cascades inspirés des compresseurs et des méthodes de démarrage des moteurs ramjet actuels ont été générés et validés à l’aide de modèles analytiques. Les concepts sont par la suite essayés expérimentalement sous la forme de cascades à l’aide d’une soufflerie supersonique. Bien que le modèle analytique montre que les cascades munies de canaux de purge soient plus performantes et plus robustes en conditions off-design, ces dernières n’ont jamais démarré lors des expérimentations même si les canaux ont été agrandis et multipliés. Ainsi, parmi tous les concepts essayés, celui qui démarre par survitesse et qui comporte des canaux de succion de couche limite à son col a donné les meilleurs résultats. Il est très stable et permet d’obtenir un ratio de pression statique de 4.25 et un recouvrement de pression totale de 89 %, pour une efficacité isentropique de 92 % à un nombre de Mach tangentiel de 2. Par contre, il est à noter qu’il n’a pas été possible de mesurer la pression totale. Elle a plutôt été estimée à partir des images de strioscopie tirées lors des essais. Comme on ne dispose pas d’une structure permettant d’essayer le compresseur rotatif à Mach 2, il a fallu approximer l’influence de l’accélération centrifuge sur l’écoulement de la cascade et trouver un moyen d’intégrer le nouvel aubage à la roue. Un modèle permettant d’estimer les paramètres d’une couche limite se développant sur une plaque plane en rotation a permis de déduire que l’accélération transverse n’aurait qu’un effet légèrement favorable, puisqu’il permet d’amincir l’épaisseur de déplacement, réduisant ainsi les risques d’interaction en la couche limite et les chocs. Finalement, les canaux de succion de couche limite du compresseur pourraient permettre d’alimenter un système de refroidissement qui limiterait la température à la jante à 820 K. Le R4E pourrait devenir l’avenir des systèmes de régénération électrique pour les véhicules hybrides. Il serait aussi intéressant pour une utilisation dans les petites centrales thermiques des régions éloignées. Ce grand potentiel d’utilisation provient de la grande densité de puissance du moteur, de sa simplicité et de son très faible coût de fabrication et de maintenance.

ABSTRACT CONCEPTUAL INTERNAL DESIGN AND COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF A SUPERSONIC INLET ALEMDAROgLU, Mine M. S., Department of Aerospace Engineering Supervisor: Prof. Dr. Yusuf &Ouml / ZY&Ouml / R&Uuml / K May 2005, 144 pages In this thesis, the conceptual internal design of the air inlet of a supersonic, high altitude, solid propellant ramjet cruise missile is performed. Inviscid, compressible CFD analysis of the designed inlet is made in order to obtain qualitative and quantitative performance characteristics of the inlet at different operating conditions. The conceptual design of the inlet is realized by using analytical relations and equations, correlations derived from numerous available past experimental data and state-of-the-art design examples. The performance estimation of the designed inlet at different operating conditions is done by using one and two dimensional gas dynamics equations. The results of the performance estimation study are compared with the results of the CFD analysis and these results are discussed in detail. A commercial tool, CFD-FASTRAN&Ograve / , is used for the CFD analysis. Inlet flow phenomena such as, different shock patterns and shock positions, performance degradation at off-design operating conditions and inlet unstart are observed. Keywords: Supersonic Inlet, Ramjet, CFD, Inlet Performance Characteristics, Operating Conditions, Unstart

ABSTRACT DESIGN OF A CONNECTED PIPE TEST FACILITY FOR RAMJET APPLICATIONS SARISIN, Mustafa Nevzat M.S., Department of Mechanical Engineering Supervisor: Asst. Prof. Dr. Abdullah ULAS Co-Supervisor: Prof. Dr. Kahraman ALBAYRAK April 2005, 164 pages Development of the combustor of a ramjet can be achieved by connected pipe testing. Connected pipe testing is selected for combustor testing because pressure, temperature, Mach number, air mass flow rate can be simulated by this type of testing. Real time trajectory conditions and transition from rocket motor (booster) to ramjet operation can also be tested. The biggest advantage of connected pipe testing is the low operation cost and simplicity. Air mass flow rate requirement is less than the others which requires less air storage space and some components like supersonic nozzle and ejector system is not necessary. In this thesis, design of a connected pipe test facility is implemented. Three main systems are analyzed / air storage system, air heater system and test stand. Design of air storage system includes the design of pressure vessel and pressure &amp / flow regulation system. Pressure and flow regulation system is needed to obtain the actual flow properties that the combustor is exposed to during missile flight. Alternatives for pressure and air mass flow rate regulation are considered in this study. Air storage system designed in this thesis is 27.8 m3 at 50 bar which allows a test duration of 200 seconds at an average mass flow rate of 3 kg/s. Air heater system is utilized to heat the air to simulate the aerodynamic heating of the inlet. Several different combustion chamber configurations with different flame holding mechanisms are studied. The most efficient configuration is selected for this study. Combustion analysis of the air heater is performed by FLUENT CFD Code. Combustion process and air heater designs are validated using experimental data. Designed air heater system is capable of supplying air at a temperature range of 400-1000 K and mass flow rate range of 1.5-8 kg/s at Mach numbers between 0.1-0.5 and pressure between 2-8 bar. Finally the design of the test stand and ramjet combustor analysis are completed. 3D CAD models of the test stand are generated. Ramjet combustor that will be tested in the test setup is modeled and combustion analysis is performed by FLUENT CFD Code. The ramjet engine cruise altitude is 16 km and cruise Mach number is 3.5. Key-words: Air Breathing Engines, Ramjet, Connected Pipe, Direct Connect, Vitiator.

The study presented in this thesis comprises the development of the longitudinal autopilot algorithm for a ramjet powered air-to-surface missile. Ramjet Missiles have short time-of-flight, however they suffer from limited angle of attack margins due to poor operational-region characteristics of the ramjet engine. Because of such limitations and presence of uncertainties involved, Robust Control Techniques are used for the controller design. Robust Control Techniques not only provide an easy limitation/uncertainty/performance handling for MIMO systems, but also, robust controllers promise stability and performance even in the presence of uncertainties of a pre-defined class. All the design process is carried out in such a way that at the end of the study a tool has been developed, that can process raw aerodynamic data obtained by Missile DATCOM program, linearize the equations of motion, construct the system structure and design sub-optimal H&amp / #8734 / controllers to meet the requirements provided by the user. An autopilot which is designed by classical control techniques is used for performance and robustness comparison, and a non-linear simulation is used for validation. It is concluded that the code, which is very easy to modify for the specifications of other missile systems, can be used as a reliable tool in the preliminary design phases where there exists uncertainties/limitations and still can provide satisfactory results while making the design process much faster.

Thesis -- University of Adelaide, 1966. / [Typescript].

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