Description:
TECHNOLOGY AREA(S): Air Platform
OBJECTIVE: Develop an analysis tool that implements a fully functional physics-based computational model to characterize the likelihood of ignition in combustors and augmentors for various configurations of flight conditions and engine hardware.
DESCRIPTION: Having the ability to predict the optimal location and energy setting of an ignition kernel in a combustor or augmentor at any/all flight conditions will, at minimum, reduce the required energy for ignition at most flight envelope conditions, extending the life of the ignition system, reducing costs to the warfighter. At best, understanding the ignition limits of a combustor or augmentor could expand the operation envelope of an aircraft currently limited by engine re-ignition, increasing the capabilities of the warfighter. Current modeling technology uses simple empirical correlations of lean blowout (LBO) to determine ignition likelihood. Empirical models [Ref. 4, 5] assume a global extinction parameter based on global conditions. These models imply a relationship between blowout physics and ignition physics that may be unfounded. The probabilistic determination of location and magnitude of delivered energy for optimal relight performance is paramount to designing a viable replacement to current ignition systems. Recent studies [Ref. 6, 7] suggest energy location relative to the cross section of the flow field may be a key factor in ignition. Examples of probabilistic phenomena may include, but are not limited to, local turbulent mixing, actual energy delivered, and plasma kernel shape variation. This analysis tool should be capable of predicting the probability of ignition at operating conditions relevant to Navy propulsion systems, which may range from below Atmospheric Temperature and Pressure (ATP) to above supercritical conditions, using JP-5 fuel better than existing models by evaluating them with relevant experimental data. The analysis tool must be made modular by specifying standardized Application Programming Interfaces (APIs) which enable the models to be utilized as libraries in turbulent reacting flow codes relevant to current and future Navy gas turbine engine applications of interest, such as operation envelope and system durability improvement. The interfaces must be independent of code-specific data structures in order to maintain generality and be well-documented for ease of use; this includes lists of all assumptions made and model limitations. The availability of conventional large eddy simulation (LES) models, finite-rate chemical kinetics, spray atomization, and spray gasification can be assumed to exist in the turbulent reacting flow codes, but all other aspects of the ignition model must be enabled through the new modules. Coordination with an Original Equipment Manufacturers (OEM) is recommended, but not required. OEM's may be a source for validation data as well as potential customers of this analysis tool.
PHASE I: Design and demonstrate the feasibility for the development of an ignition model to probabilistically predict the likelihood of light-off for fuels relevant to Navy. Develop a plan for implementing the model via APIs with standard interfaces that are well-documented.
PHASE II: Develop and demonstrate detailed verification and validation of the prototype design tool to probabilistically predict the likelihood of light-off with JP-5. Demonstrate the model as APIs in reacting flow codes relevant to current and future Navy engine applications of interest. Deliver prototype analysis tool libraries and documentation.
PHASE III: Refine and finalize, as needed, the Phase II developed ignition analysis tool, allowing the government to internally support design, performance, operability, and/or lifing analysis of naval propulsion systems such as gas turbine engine combustors and augmentors that implement ignition processes. Potential sources of validation data and customers of the model libraries include gas turbine engine OEM's. Private Sector Commercial Potential: Any combustion application in the commercial sector will be able to apply this technology to determine light-off or ignition. These include, but are not limited to, internal combustion engines and power generation turbine engines.
REFERENCES:
1. Neophytou, A., & Mastorakos, E. (2012). SPINTHIR: An ignition model for gas turbines [Video file]. Retrieved from http://www.dspace.cam.ac.uk/handle/1810/243651
2. Krisman, A., E. R. Hawkes, A. Bhagatwala, M. Talei, and J. H. Chen. (2014). A Direct Numerical Simulation Investigation of Ignition at Diesel Relevant Conditions. Proceedings of 19th Australasian Fluid Mechanics Conference, Melbourne, Australia. Retrieved from https://www.researchgate.net/profile/Alex_Krisman/publication/267640174_A_Direct_Numerical_Simulation_Investigation_of_Ignition_at_Diesel_Relevant_Conditions/links/5457136f0cf2bccc490f3a5b.pdf
3. Luong, M. B., Yu, G. H., Lu, T., Chung, S. H., & Yoo, C. S. (2015). Direct numerical simulations of ignition of a lean n-heptane/air mixture with temperature and composition inhomogeneities relevant to HCCI and SCCI combustion. Combustion and Flame, 162(12), 4566-4585. Retrieved from http://www.sciencedirect.com/science/article/pii/S0010218015003181
4. King, C.R. (1957). A semi-empirical correlation of afterburner combustion efficiency and lean-blowout fuel-air-ratio data with several afterburner-inlet variables and afterburner length. National Advisory Committee for Aeronautics. NACA RM E57F26
5. Huelskamp, B.C., Kiel, B.V., Lynch, A.C., Stanislav, K., Gokulakrishnan, P.,Klassen, M.S. (2011). Improved correlation for blowout of bluff body stabilized flames. Proceedings of the 49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum
6. Sforzo, B., Kim, J., Seitzman, J.M., Jagoda, J. (2011). Spark kernel energy and evolution measurements for turbulent non-premixed ignition systems. Augmentor Design Systems Conference. Ponte Verda Beach, FL, March 16-18
7. Sforzo, B., Kim, J., Lambert, A., Jagoda, J., Menon, S., Seitzman, J. (2013). High energy spark kernel evolution: measurement and modeling. Proceedings of the 8th US National Combustion Meeting. Retrieved fromhttps://www.engineeringvillage.com/share/document.url?mid=cpx_594c68f01509076a465M753910178163171&database=cpx&view=abstract-
KEYWORDS: Combustion; Ignition; Plasma; Combustor; Augmentor; Modeling
