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Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT: The hydrocarbon-fueled scramjet is capable of providing hypersonic air-breathing propulsion for high-speed applications. The effective operation of high-speed air-breathing engines (ram- and scram-jets) over a wide range of flow parameters (velocity and altitude) is one of the most technically difficult challenges in the design of hypersonic vehicles. The most promising approach to overcome these difficulties is a scramjet having flexible gasdynamic configurations that meet a number of extremely challenging technical issues such as mitigation of unsteady separation, peaks of thermal loads, material durability, etc. Combustion Science & Engineering, Inc. and the University of Notre Dame propose to use a plasma-based combustion actuator, several types of sensors, and robust algorithm of feedback control built on predictive scenarios to permit stable operation of the combustion process during scramjet operation. The main advantage of plasma application for control of fuel ignition/combustion is due to the non-equilibrium, non-uniform, and transient nature of electrical discharges, which deliver a synergy with thermal effects (heating). The work proposed will focus on the use of passive sensors, due to the robustness of these devices and relatively low complexity of implementation in actual flight hardware.; BENEFIT: The tangible result of this project will be an apparatus for controlling combustion in high-speed flows. This apparatus will use passive sensor(s) and a plasma-actuator to allow vehicles, such as ramjets and scramjets, to operate across the entire flight envelope and through flight transitions where flameholding and flame instabilities can be difficult. The products developed in this work will be useful technologies in the aircraft industry to allow for improved operation for all high-speed vehicles. An obvious market for the technology is the United States military, which have been developing high-speed vehicles such as the ramjet and scramjet for nearly 50 years. Safe and stable operation of these vehicles has proven difficult due to the wide variably in engine conditions during flight, especially during transitions between flight modes. Therefore, there is a substantial need for this technology for the military to maximize the operability of these aircraft. The technology, however, is not just applicable to the military. Non-military aircraft also can benefit from technology to identify and mitigate combustion stability issues, especially as an additional safety measure for passenger planes.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT: Afterburners operate under a wide range of operating conditions and hence they are likely to encounter conditions at which combustion (thermoacoustic) instabilities occur. Therefore, methods to mitigate rumble and screech, usually classified as either active or passive control, are of clear interest. CSE, Inc. proposes to develop a strategy to design passive-control systems, in particular damping devices, to mitigate combustion instabilities in afterburners. Passive-control methods for afterburners have been under development for more than half a century. In spite of this plethora of passive-control devices and apparently good understanding of their basic physics, in particular for damping devices as highlighted above, the problem is that in practice passive control techniques tend to be applied on a (very) costly trial and error basis. CSE, Inc. proposes to develop a strategy to design passive-control systems, in particular damping devices, to mitigate combustion instabilities in afterburners. This strategy is centered around an acoustic solver and is assisted by theory and CFD simulations. However, the present idea of using theory and CFD to assist acoustic-solver simulations in the time-domain can be applied to the design of any active- or passive-control method, and to any type of combustor. BENEFIT: Passive-control methods for afterburners are currently designed via a costly trial and error process. Thus, there is a need for computationally tractable, design-specific analyses that could reduce these costs and, as a result, make the development of new devices more attractive. The obvious market for this software is the OEMs designing damping devices for afterburners. However, due to the broad range of applicability of the proposed strategy, it is applicable to any passive-control method and to any type of combustor. This feature enhances the commercial success of the proposed approach by making it more appealing to a broader market, that includes the expanding gas-turbine industry.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2015

ABSTRACT: The U. S. Air Force needs turbulent combustion models that can be used to simulate combustion in actual propulsion systems at both design and off-design conditions, not models that are only useful for highly idealized problems. With this motivation in mind, Combustion Science & Engineering, Inc. and the Computational Combustion Lab at Georgia Tech plan to enhance current capabilities to simulate combustion in aero-turbine engines, augmentors/afterburners, ramjets and scramjets by improving the limitations of what was found to be the framework that can potentially capture most of the combustion physics relevant to these devices: the Linear-Eddy-Model. This goal includes most propulsion systems of interest to the USAF and, consequently, targets two of four game changing technologies identified by the USAF, hypersonics and fuel-efficiency technologies. To achieve this goal, the developmental work will be guided by thorough Verification & Validation tests. These tests will avoid the practice of using meshes that are so fine that the contribution of the subgrid model to the solution is negligible and will consider various combustion regimes. From a commercial standpoint, the outcome of this research effort will be a software library, a modular API, based on LEM that could be plugged into any CFD code.; BENEFIT: This project will develop a software suite that will enhance current capabilities to simulate combustion in aero-turbine engines, augmentors/afterburners, ramjets and scramjets over a wide range of operating conditions. The product developed in this work will be a useful tool for supersonic and hypersonic vehicle design applications for the U. S. Air Force. Discussions with engine design teams indicate that the capabilities of this project will greatly enhance current design tools in use by equipment manufacturers. Also the market for this product will include gas turbine designers and manufacturers for both military and civilian aircraft. The use of this tool will significantly reduce development costs by eliminating some design iterations and hardware testing, which is quite expensive and time-consuming. Because of the broad range of applicability of the model, it will be useful for other flight vehicle systems, such as interturbine burners, new concepts for high speed aircrafts. It will also be useful to predict blowout and ignition. Therefore, the potential market for this tool is fairly large and ranges over a number of different industries.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 748.21K | Year: 2015

ABSTRACT:The pressure oscillations associated with thermoacoustic combustion instabilities are a serious hazard to combustion systems such as gas-turbine-engine combustors, augmentors / afterburners, ramjets, and rocket engines. Unfortunately, combustion engineers currently face a dilemma when trying to estimate these potentially destructive phenomena. Engineers can obtain a quick insight into these instabilities with tools of very limited predictive capability, or they can use CFD, which can be deemed predictive but is too computationally expensive for practical use. A tool must be developed to bridge this huge gap in predictive capability and computational cost. With this in mind, Combustion Science & Engineering, Inc. will develop a software suite to estimate thermoacoustic combustion instabilities that will use a novel CFD / acoustic-solver strategy. This hybrid strategy uses mature concepts from CFD, acoustics modeling, and multiscale methods not applied yet to problems in combustion instabilities. Although this strategy is not trivial to implement, it can be developed in 2 years with a high probability of success. This software suite will also be able to conduct classic analyses and CFD simulations, providing combustion engineers with a well-rounded tool. At the end of Phase II, a software suite will be validated and ready for beta testing.BENEFIT:An important product from this project will be a suite of computational tools to analyze the thermoacoustic behavior of augmentors and combustors. These modeling tools can be used for a variety of applications, including the design and testing of these systems. This will be an important design tool for most propulsion systems, including gas turbines applications, for predicting combustion instabilities. This suite of modeling tools is very versatile such that the user can conduct a variety of analyzes of varying complexity and operating conditions. This product will give the design engineer much more freedom to test new combustor designs operating at wider range of pressures, temperature and fuel / air mixtures. The software suite proposed here will bridge a current gap in predictive power to estimate combustion instabilities and, consequently, will have a broad range of applicability, something which contrasts with traditional combustor-dependent tools. As a result, the proposed software will be readily useful to a wide range of combustion systems of interest to the military, such as gas-turbine-engine combustors, augmentors/afterburners, and ramjets, all of which are prone to the damaging pressure oscillations associated with combustion instabilities. Gas-turbine-engine combustors are widely used in the military since they are the prime movers of aircrafts, tanks, and some combat ships. Regarding augmentors/afterburners, these devices are of military importance because aircrafts use them to obtain bursts in thrust, such as those needed during takeoff, climb, missile evasion, and combat maneuvers; some of the aircraft in service that use augmentors include the F15, F16, F18, F22, and F35 (still in production). There is a need for tractable, design-specific thermoacoustic analyses in the gas-turbine community. This software will be used by both the design and testing communities. The product developed in this work will be a useful tool for subsonic, supersonic and hypersonic vehicle design applications for the US Air Force. Discussions with engine design teams indicate that the capabilities of this project will greatly enhance current design tools in use by equipment manufacturers. Also the market for this product will include gas turbine designers and manufacturers for both military and civilian aircraft. The use of this tool will significantly reduce development costs by eliminating some design iterations and hardware testing, which is quite expensive and time-consuming. This tool will be applicable to any propulsion system that utilizes combustion for energy input, including afterburners or augmentors, interturbine burners or any new concept for increasing gas turbine efficiency and power. In addition, the capability to model thermoacoustic processes is also important in a variety of stationary power generation applications, including large gas turbines used for electrical power generation or microturbines used for distributed power generation. Furthermore, this capability is useful to other combustion systems, such as used in boilers or furnaces.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

ABSTRACT: The need for improved performance of liquid rocket engines requires efficient wall cooling technologies to mitigate high heat fluxes from hot combustion gases to the engine wall in the thrust chamber. High heat fluxes to the chamber liners can be overcome by fuel film cooling (FFC) of the inside chamber using the liquid propellant. Moreover, the thermal cracking of the fuel creates coke deposition which acts as a thermal barrier coating. However, FFC is not well understood due to complex interactions between the vaporization of the multi-component liquid film and the hot combustion gases. Therefore, in order to better understand pyrolysis of RP fuels under FFC conditions, an experimental and modeling study will be performed to investigate various coke deposition mechanisms in a controlled environment relevant to FFC rocket engine conditions. An in-situ measurement technique based on thin film IR absorption for coke deposition thickness will be developed. The experimental data obtained in the proposed work will be used to develop detailed and reduced chemical kinetics models for coke deposition. The computationallyaffordable global and quasi-global reduced kinetics models for RP fuel oxidation and coke deposition will be implemented in CFD to simulate rocket engine FFC.; BENEFIT: The ultimate result of this research will be a comprehensive chemical kinetic mechanism that can be used to generate reduced kinetics models that can be implemented in CFD for predicting coke deposition of jet fuels, especially RP fuels. CSE has developed a detailed five-component surrogate kinetics mechanism for aviation grade fuels through previous SBIR programs funded by the U. S. Air Force. This well-validated comprehensive kinetic mechanism will be incorporated into the chemical kinetic modeling software, rkmGen, developed by CSE in an earlier SBIR supported by the Air Force (Contract# FA8650-11-C-2188). This product will facilitate the ability of the U. S. Military and engine OEMs to easily obtain high fidelity model predictions for the coking properties of RP-2, JP-8, and Jet-A fuels at conditions relevant to various engine applications. In addition, the detailed surrogate kinetic mechanism will be used to derive reduced kinetic models using rkmGen software for the CFD simulations of practical applications. CSE anticipates that the revenue from this work will be generated from providing both engineering services to the OEMs and USAF and through the licensing of the tool. The product developed in this work will be a useful tool for rocket and missle applications for the US Air Force and engine OEMs. Discussions with engine design teams indicate that the capabilities of this project will greatly enhance current design tools in use by equipment manufacturers. The use of this tool will significantly reduce development costs by eliminating some design iterations and hardware testing, which are both expensive and time-consuming. This tool will be applicable to any system in a rocket engine that utilizes coke deposition for liner protection.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 749.97K | Year: 2015

ABSTRACT: In recent years, diversification of energy dependence on foreign oil has attracted the use of alternative fuels such as the Fischer-Tropsch jet fuels and hydro-treated renewable jet fuels. However, there are combustion stability issues with alternative fuels in the aircraft engines including augmentors. In addition, the U.S. military has been using JP-8 as the single battle field fuel to power both diesel engines and generators for electricity. However, operating compression ignition engines with JP-8 have encountered various technical and performance related issues. Therefore, it is important to study the effect of chemical and physical properties of JP-8 and alternative fuels on combustion at conditions relevant to augmentors and diesel engines. Combustion Science & Engineering, Inc. (CSE) has developed a detailed surrogate kinetic mechanism to model the combustion characteristics of jet fuels including alternative fuels. In the current work, CSE will acquire new experimental data at low pressure augmentor conditions as well as high pressure diesel engines conditions with jet fuel and it surrogate components. These experimental data will be used to improve and validate the CSE surrogate kinetic mechanism for wide range of conditions including augmentors and diesel engines with vitiation. BENEFIT: The ultimate result of this research will be a comprehensive chemical kinetic mechanism that can be used for predicting combustion properties of petroleum-based jet fuels as well alternative fuels. CSE has developed a four-component surrogate kinetic model for augmentor conditions with vitiation in an earlier SBIR. This model will be improved and validated against the experimental data obtained in the current work at low pressure augmentor conditions as well as high pressure diesel engines conditions. This detailed surrogate mechanism will benefits U.S. Military to evaluate the combustion properties of various jet fuels where experimental data are not available. In addition the detail kinetic model that will be developed in this work will be incorporated into the rkmGen software, which has been under development through an Air Force funded SBIR with CSE. rkmGen is a GUI-driven chemical kinetic software that can be used for various chemical kinetic computations including the development of reduced kinetic models. Therefore, outcome of this work will benefits the OEMs as well as CFD users and vendors.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2014

ABSTRACT: The ability of plasmas to modify combustion has been known for more than 50 years. Recent advances in plasma generation technology and measurement diagnostics have led to extensive efforts to understand both the kinetics of the plasma-flame interaction and the enhancement of combustion properties such as ignition, extinction, flame speed and dynamics. Combustion Science & Engineering, Inc. proposes to develop a kinetic model of plasma-enhanced vitiated combustion for hydrocarbon fuels including JP-8 by coupling the existing CSE vitiated kinetics model with plasma-flame chemistry developed in the current work. In parallel with the model development, CSE will work with Purdue University to develop and apply a new optical diagnostic for absolute measurement of radical species: Two-Color, two-photon laser-induced Polarization Spectroscopy (TCPS). The overall goal of this work is the development and validation of a kinetic model of JP-8 plasma-enhanced combustion under vitiated (or augmentor relevant) conditions. Propane and ethylene have been chosen as the initial fuels for experimental convenience. In Phase II we will extend both the model and experiments to JP-8, and extend the TCPS diagnostic to O atoms. We will also make extinction and ignition measurements under plasma-enhanced vitiated conditions. BENEFIT: An important product from this project will be a comprehensive jet fuel surrogate kinetic model that includes the validated platform for modeling plasma-assisted combustion. This mechanism will be specifically targeted at conditions typical of augmentors, inter-turbine burners and diesel engines that use either vitiation or exhaust gas recirculation (EGR). In addition, an industrial partner is also interested in the current proposed work as it focuses on applications for small jet engines. We believe that this tool could readily lead to the design of a plasma-assisted combustion system suitable for use in augmentors or afterburners, where flame stability and relight issues can affect performance.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 150.00K | Year: 2014

ABSTRACT: Ramjets and scramjets are the preferred propulsion platforms for flight in the supersonic (3


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2013

ABSTRACT: In recent years, diversification of energy dependence on foreign oil has attracted the use of alternative fuels such as the Fischer-Tropsch jet fuels and hydro-treated renewable jet fuels. However, there are combustion stability issues with alternative fuels in the aircraft engines including augmentors. In addition, the U.S. military has been using JP-8 as the single battle field fuel to power both diesel engines and generators for electricity. However, operating compression ignition engines with JP-8 have encountered various technical and performance related issues. Therefore, it is important to study the effect of chemical and physical properties of JP-8 and alternative fuels on combustion at conditions relevant to augmentors and diesel engines. Combustion Science & Engineering, Inc. (CSE) has developed a detailed surrogate kinetic mechanism to model the combustion characteristics of jet fuels including alternative fuels. In the current work, CSE will acquire new experimental data at low pressure augmentor conditions as well as high pressure diesel engines conditions with jet fuel and it surrogate components. These experimental data will be used to improve and validate the CSE surrogate kinetic mechanism for wide range of conditions including augmentors and diesel engines with vitiation. BENEFIT: The ultimate result of this research will be a comprehensive chemical kinetic mechanism that can be used for predicting combustion properties of petroleum-based jet fuels as well alternative fuels. CSE has developed a four-component surrogate kinetic model for augmentor conditions with vitiation in an earlier SBIR. This model will be improved and validated against the experimental data obtained in the current work at low pressure augmentor conditions as well as high pressure diesel engines conditions. This detailed surrogate mechanism will benefits U.S. Military to evaluate the combustion properties of various jet fuels where experimental data are not available. In addition the detail kinetic model that will be developed in this work will be incorporated into the rkmGen software, which has been under development through an Air Force funded SBIR with CSE. rkmGen is a GUI-driven chemical kinetic software that can be used for various chemical kinetic computations including the development of reduced kinetic models. Therefore, outcome of this work will benefits the OEMs as well as CFD users and vendors.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2013

ABSTRACT: Combustion instabilities can be a serious problem in combustion devices including augmentors/afterburners. Their prediction is very challenging due to nonlinear interactions between various complex phenomena, including acoustics, combustion, and turbulence. The goal of this project is to provide a framework that will allow the development of new models of combustion instabilities benefiting from an open, large, and multi-disciplinary community of researchers, a framework needed to tackle difficult multi-physics problems such as combustion instabilities. To accomplish this goal, OpenFOAM will be used to develop two models for combustion instabilities: a CFD model and a nonlinear acoustics model. A CFD model is needed as it has the potential to be truly predictive; however, they are computationally complex and expensive. A nonlinear acoustic model is more computationally tractable in the short term and provides a viable validation tool for the CFD model. Linear models are not considered because they have been amply studied and cannot provide information about limit cycles. For Phase I, this work will use simple combustion-instabilities problems to evaluate current CFD models in OpenFOAM, plan potential modifications to these models, and develop a nonlinear acoustic model in OpenFOAM. A plan to conduct new experiments for Phase II will be devised. BENEFIT: Combustion instabilities are thermo-acoustic phenomena characterized by pressure oscillations with well-defined frequencies and with amplitudes that can be large enough to cause damage to a combustor. Tools that can predict potential combustion instabilities in early design stages will considerably reduce costs associated with the design and testing of gas turbine engines. Hence, the tools developed here will be of considerable interest to the gas turbine industry. From a broader perspective, again due to the multi-physics nature of combustion instabilities, the expertise developed by CSE in this project about these instabilities and OpenFOAM can be easily extended to other projects of interest such as prediction of blow-off in augmentors, study of basic aspects of flame extinction and reignition, prediction of pollutant formation from flames, and design of industrial burners with CFD. This expertise can be sold to a wide variety of industries, something which CSE has been doing for more than ten years. The market size for the technology developed in this project is over $10M due to the many potential applications and the pervasiveness of these issues.

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