Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2010
The Air Force has identified a number of key issues for combustion systems as attention turns towards “logistic fuel replacements” (e.g., JP-8 in the near term; Fischer-Tropsch derived fuels from coal, bio-oils or other feedstocks in the mid term blended with JP-8; and/or bio-derived fuels such as fatty acid methyl ester—FAME; or hydroprocessed vegetable oils-HVO in the longer term). In addition, DARPA’s biojet program can be looked to for guidance on specific direction in future fuels for the near and long term. The proposed project will conduct experiments directed at determining the role of fuel type on atomization, evaporation, and combustion behavior of such fuels. In parallel, models associated with the atomization and evaporation phenomenon will be assembled and evaluated for their ability to predict the measured behavior. Where possible, these models will be improved so that they can better capture the effect of fuel type on the characteristics which are key to performance of spray based systems. The assembled package of improved models will be standalone or integratable into CFD environments. The high quality, detailed data set obtained can be also used to validate third party modeling approaches as well. BENEFIT: The proposed experiments will provide important fundamental data on atomization, evaporation, and combustion of sprays for various alternative fuels as injected by different atomizer types in different environments. This information will be of interest to commercial engine and injector manufacturers as they improve fuel flexibility of their products. Industrial partners can also utilize the information obtained from the experiments. The improved models developed and validated will be of interest to these same end users as a means to help them improve existing products and develop new ones.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 99.88K | Year: 2004
Injection of a liquid stream into a high-speed crossflow is applicable to many combustion applications including gas turbine augmentors. As a result, liquid stream injection has been studied extensively in recent years. Theses studies have resulted in some design tools directed at jet breakup length, jet penetration, and spray features. Despite these studies, however, wide variations in expressions describing even basic features, such as jet penetration, are apparent, reaffirming the lack of sufficient design tools. Currently, a comprehensive physics-based design code (i.e., computational fluid dynamics (CFD)) cannot deal with breakup, secondary atomization, and strong phase coupling. The most advanced codes with relatively quick turnaround require many assumptions and simplifications regarding the spray to be made, such as representing the spray with an average droplet size (e.g., Sauter Mean Diameter), and spherical particles. Hence, to provide an accurate description of the augmentor efficiency, light off, and stability, improvements in design tools are required. In particular, tools that provide characteristics associated with the spatial and temporal distribution of the fuel, evaporation, and mixing that can be applied efficiently are key. This proposal outlines a non-CFD based approach to ensure maximum usability and rapid turnaround.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2005
Injection of a liquid stream into a high-speed crossflow is applicable to many combustion applications was well as other general applications. As a result, liquid stream injection has been studied extensively in recent years. Theses studies have resulted in some design tools directed at jet breakup length, jet penetration, and spray features. Despite this progress, however, wide variations in expressions describing even basic features, such as jet penetration, are apparent, reaffirming the lack of sufficient design tools. Relative to CFD applications, correlations developed largely in an empirical manner from data at non-augmentor like conditions are assembled and used to generate source terms within the CFD domain that are associated with the droplets. The current project will develop and validate models describing key phenomena such as jet breakup, droplet sizes, vaporization, mixing and the subsequent spatial and temporal distribution of the fuel. Extensive data will be collected using experiments designed to provide the necessary information to validate the models. The validated models will be assembled into a standalone analytical tools as well as a CFD subroutine that will be incorporated into a CFD code.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 1.15M | Year: 2008
The Air Force has identified a need for improved design tools for augmentor performance. In the near term, it is apparent that reduced order models are needed in order to assist in the design process by providing engineering estimates of combustion instability. One key area that requires effort is the area of screech modeling. A critical aspect of any model that attempts to predict screech is the correct representation of the dynamic heat release rate. In this Phase I SBIR, Energy Research Consultants and its partner, Georgia Institute of Technology will join together to 1) develop a reduced order heat release model, and 2) conduct experiments in augmentor like conditions to validate the model. Georgia Tech’s experience with combustion oscillations combined with unique experimental facilities at ERC will provide the right combination of resources to efficiently develop the design tool needed. Based on success with the Phase I efforts, in Phase II, transverse mode instabilities will be incorporated along with non-homogeneous mixtures (both single and two phase). These conditions, along with the longitudinal modes already demonstrated in Phase I, will provide a wide range of data against which to validate the modeling approach.
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2014
In liquid fueled combustion systems it is necessary for the fuel to vaporize prior to combustion. As a result, a method to quantify the amount of vapor that exists in the spray plume is desired in order to help understand the evaporation process. Such results are also useful in validating detailed computer models of this same process. Unfortunately, such a measurement is very difficult in practice due to the complex interaction of the spray droplets with any method applied. The objective of the proposed effort is to develop a robust diagnostic method to quantify the planar concentration of fuel vapor, fuel liquid, and gas phase temperature in a spray plume. The method proposed is to use multi-angular light extinction using collinear laser beams of specific wavelengths generated by tunable diode lasers. The wavelengths selected will allow differences in the absorbed light to be used to quantify fuel vapor, fuel liquid and gas temperature. Laser extinction is a very robust reliable method and the use of differential absorption eliminates challenges with windows, droplets effects, and dense spray issues that tend to plaque laser sheet imaging methods typically used. In Phase I, proof of concept will be demonstrated for a fuel spray for a liquid of interest (e.g., gasoline). The spectroscopy of gasoline will be evaluated to select appropriate wavelengths and appropriate tunable diode laser blocks identified. The identified wavelengths will be assembled into a breadboarded system and applied to a series of experiments to demonstrate proof of concept. These will range from particle laden jets of air doped with a hydrocarbon vapor to a gasoline spray injected by a typical automotive injector. Single collinear beams will be used in Phase I and multiple paths through the spray will be measured and deconvolved using tomographic analysis methods. Evaluation of potential time-resolved information will be carried out. Commercial Application and Other Benefits: The proposed instrument fills a significant niche in the diagnostics market for spray characterization. If successful this instrument will be of great interest to a wide range of OEMs and component suppliers for fuel injectors for many applications. The data generated can be used to gain insight into the fuel injection process and also provide important validation data for models. With validated models, fuel injector and combustion designers can more efficiently develop higher efficiency, clean burning liquid fueled engines.