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Energy Research Consultants
Lagunal Hills, CA, United States
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Brown C.T.,Energy Research Consultants | Mondragon U.M.,Energy Research Consultants | McDonell V.G.,Energy Research Consultants
AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting | Year: 2017

Combustion instabilities can cause serious challenges for gas turbine combustion systems. In the current work, mixing of two streams upstream of the flameholder is used to generate inhomogeneities in the flow approaching the flameholder. Both longitudinal and traverse self-excited acoustic signatures were developed for various operating conditions. The incorporation of two circuits creates substantial spatial gradients in temperature, velocity, and equivalence ratio depending on the conditions, and facilitates the successful generation of the desired self-excited conditions. Further, a Matlab based analysis tool, validated with extensive data, was used to guide how to change the fuel placement to affect a change in the acoustic signature. It is shown that spatially altering the fuel distribution per the analysis tool can suppress the self-excited acoustics for various conditions. The data obtained can be used as a means to validate reduced order models describing combustion instabilities for this type of system. © 2017 by the American Institute of Aeronautics and Astronautics, Inc.

Vaillancourt K.,Research Center | Alcocer Y.,Research Center | Bahn O.,HEC Montréal | Fertel C.,Research Center | And 8 more authors.
Applied Energy | Year: 2014

In terms of energy resources, Canada is an important player on the world scene. However, the energy systems of the Canadian provinces and territories are much diversified and a national energy strategy is missing in order to optimize the management of energy systems.The objective of this paper is twofold. First, we introduce TIMES-Canada, a new multi-regional energy model that has been developed using the most advanced TIMES optimization modeling framework, while keeping a very high level of details in the database (5000 specific technologies; 400 commodities) compared with other Canadian energy models. Second, we define and analyze possible futures for the Canadian integrated energy system on a 2050 horizon, under five different baselines: a Reference scenario as well as four alternate scenarios corresponding to different oil prices (Low and High) and socio-economic growth trends (Slow and Fast).In our Reference scenario, we show that the Canadian final energy consumption is expected to increase by 43% between 2007 and 2050. The Fast scenario leads to the maximum increase compared with the Reference scenario (21% in 2050). In all scenarios, oil products will continue to dominate on the long term, although in a decreasing proportion over time (from 43% in 2007 to 29% in 2050) in favor of electricity (31% of the additional demand in 2050) and biomass/biofuels. Regarding the corresponding optimal energy production paths, we illustrate two main trends: (1) a gradual replacement of onshore conventional oil & gas sources by unconventional and offshore sources (oil sands is expected to represent half of the production in 2050), and (2) a significant penetration of renewables in the electricity mix is shown after 2035 due to increases in oil import prices and decreases in renewable technology costs. The development and calibration of such a detailed technology-rich model represent an important contribution for Canada: TIMES-Canada is the only optimization model covering in details the large diversity of provincial energy systems on a long term horizon. © 2014 Elsevier Ltd.

Wang Q.,Energy Research Consultants | Mondragon U.M.,Energy Research Consultants | Brown C.T.,Energy Research Consultants | McDonell V.G.,Energy Research Consultants
Atomization and Sprays | Year: 2011

The injection of a plain liquid jet into a gaseous crossflow has been studied extensively. Empirical models describing the aspects of the breakup, penetration, and dispersion of the liquid jet have been developed based on experimental data. In recent years, however, more sophisticated simulation approaches such as surface-tracking methods have evolved, and as a result, a richer database for assessing accuracy is of great interest. In parallel, advancements in imaging diagnostics that can capture details regarding the breakup processes have occurred, creating an opportunity to provide new types of results that can be used for model validation. While imaging methods are convenient to apply, extraction of the necessary quantitative information to compare directly with advanced simulation methods requires considerable effort. Due to the vast amounts of data that can be generated in a matter of seconds, manual analysis of the images obtained can be tedious. As a result, automated methodologies for extracting this information are necessary. The present work describes the application of automated processing routines to the breakup of a plain liquid jet in a crossflow under varying conditions. The results extracted are used to generate correlations for column break point time, trajectory, and the dynamics of the breakup and liquid column characteristics. The correlations are compared with prior expressions generally derived from much smaller datasets and found to exhibit some significant differences, particularly with respect to the break time. These expressions can be incorporated into atomization models within computational fluid dynamics packages or as part of a standalone atomization model. © 2011 by Begell House, Inc.

Shin D.-H.,Georgia Institute of Technology | Plaks D.V.,Georgia Institute of Technology | Lieuwen T.,Georgia Institute of Technology | Mondragon U.M.,Energy Research Consultants | And 2 more authors.
Journal of Propulsion and Power | Year: 2011

This paper describes an investigation of the response of bluff body stabilized flames to harmonic oscillations. This problem involves two key elements: the excitation of hydrodynamic flow instabilities by acoustic waves, and the response of the flame to these harmonic flow instabilities. In the present work, data were obtained with inlet temperatures from 297 to 870 K and flow velocities from 38 to 170 m=s. These data show that the flame-front response at the acoustic forcing frequency first increases linearly with downstream distance, then peaks and decays. The corresponding phase decreases linearly with axial distance, showing that wrinkles on the flame propagate with a nearly constant convection velocity. These results are compared with those obtained from a theoretical solution of the G-equation excited by a harmonically oscillating, convecting disturbance. This kinematic model shows that the key processes controlling the response are 1) the anchoring of the flame at the bluff body, 2) the excitation of flame-front wrinkles by the oscillating velocity, 3) interference of wrinkles on the flame front, and 4) flame propagation normal to itself at the local flame speed. The first two processes control the growth of the flame response and the last two processes control the axial decrease observed farther downstream. These predictions are shown to describe many of the key features of the measured flame response characteristics. Copyright © 2010 by Dong-Hyuk Shin, Dmitriy V. Plaks, Tim Lieuwen, Ulises M. Mondragon, Christopher T. Brown, and Vincent G. McDonell.

Emerson B.,Georgia Institute of Technology | Mondragon U.,Energy Research Consultants | Acharya V.,Georgia Institute of Technology | Shin D.-H.,Georgia Institute of Technology | And 3 more authors.
Combustion Science and Technology | Year: 2013

This article describes measurements of the response of bluff-body stabilized flames subjected to transverse acoustic waves. It is the first of a two-article series. The objective of this work was to extend prior studies of this nature to much higher Reynolds numbers and more severe environments that more closely mimic conditions encountered in applications. To this end, experiments were performed at flow velocities of 50 mls and 100 mls with inlet air temperatures ranging from 475-750 K. Two different modes of acoustic excitation were applied, corresponding to velocity and pressure nodes/antinodes along the combustor centerline. High-speed imaging and phase-locked particle image velocimetry (PIV) were used to characterize the spatio-temporal flame front and velocity field response. The data show that the disturbance field and the flame front response amplitude exhibit a nonmonotonic spatial distribution with interference patterns. The phase of the flame front response at the forcing frequency varies nearly linearly with downstream distance, and corresponds to a phase speed that is slightly less than the mean flow velocity. Significantly, these results show that the key features of the flame's magnitude and phase characteristics are quite similar to those observed in much lower flow velocities. Copyright © Taylor & Francis Group, LLC.

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 80.00K | Year: 2013

This Phase I project will demonstrate how control of fuel and/or air distribution can be used to mitigate combustion oscillations. The project will be done with the perspective that the mechanism of controlling the oscillastions can eventually be implemented into a retrofittable, closed loop approach. It has been well established that the relationship between the location and timing of local heat release can couple with acoustic modes in the augmentor. Examples of exploiting this by pulsing fuel at the correct phase to mitigate can be found, but the requirements for the fast pulsing preclude practical implementation. In the proposed project, spatial movement of the heat release rather than temporal will be demonstrated through a combination of fuel and air placement. The effort will utilize an existing test rig with two-stream mixing to mimic the fan and core air streams. This offers the ability to explore manipulation of the oxidizer stream in addition to fuel placement as a migigating strategy. Complimenting the tests will be the development of analytical flame response transfer functions which will help interpret the reasons the control measures work.

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.00M | Year: 2015

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, laser absorption was successfully applied to determine fuel vapor concentration within a gasoline spray plume using existing lasers and available wavelengths. Several wavelength pairs were evaluated for performance and some limitations were identified with the existing lasers. This led to identification of other available lasers/wavelengths that should be pursued to optimize the system performance in Phase II. In addition, laser absorption was demonstrated for determining the gas phase temperature. A concept for doing these measurements simultaneously was developed which is straightforward. The framework for applying tomography (to generate planar images of the vapor and temperature fields) for multi-path, multi-wavelength TDLAS was established. Initial coding was carried out to allow planar reconstruction of an asymmetric spray. An initial opto-mechanical design (lasers, controllers, fiber optics, detectors) for a fully integrated system including the strategy to gather results from multiple angles was developed. In addition, light scattering models were developed in MatLab to simulate and account for known wavelength dependent scattering when using multiple wavelengths. In Phase II, the wavelengths for optimum simultaneous probing for fuel vapor and temperature will be finalized and procured. This step will be done in conjunction with establishing the necessary temperature dependent spectroscopy of gasoline for these wavelengths along with consideration for any interfering species (e.g., water, carbon dioxide). The expected improved performance using these wavelengths will be verified in gasoline sprays under non-reacting and reacting conditions and at high pressure conditions. The initial opto-mechanical design developed in Phase I will be refined and optimized for the recommended wavelengths. The tomography framework will be further evolved to incorporate the finalized opto-mechanical design. System software with an initial graphical user interface will be developed for a prototype instrument that will be assembled in Phase II. The overall system will be sufficiently refined such that it can be used for trade show demonstrations as well as for demonstration at potential customer locations. A number of OEM supporters have been identified and have provided letters indicating interesting in the instrument and allowing access to practical automotive research facilities with optical engines. A major instrument vendor has indicated support for helping ERC evolve the prototype to a commercial product and to provide appropriate licensing options. 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 which will reduce fuel costs and reduce pollutant emissions.

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

ABSTRACT:This project will develop fuel injection technology that is inherently insensitive to variation in liquid physical properties. Generally physical properties can impact the injector discharge coefficient which in turn impacts liquid velocity and mass flow for a given injector pressure drop. Under certain circumstances, the discharge coefficient can be made to be insensitive to these properties. Hence the approach taken is to modify the injector configuration to consistently behave as it would under these certain circumstances. Extensive experimental and simulation work will be used to create configurations with a wide range operation under these conditions.BENEFIT:The benefits of this development will be injectors for fuel or other fluids which have no dependency on liquid physical properties. This will result in reduced variation in injection velocity and associated penetration. The conditions that will be targeted are also expected to provide improved atomization behavior which has potential benefit for many combustion systems.

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: 150.00K | Year: 2015

ABSTRACT: The proposed work will lead to the development of time efficient design tools that are based on flame transfer functions. The design tool is a matlab based code that can be used to predict how changes from a base configuration will impact the propensity for screech. As a result, it can be used to help guide design of augmentors in terms of fuel placement and overall geometry. In a potential Phase II, the flame transfer functions will be incorporated into an overall acoustic code which can further guide design of the augmentor in terms of avoiding combustion instabilities. BENEFIT: The benefits of this project include both data and design tools that can be used to help designers of combustion systems avoid combustion instabilities. Because combustion instabilities affect all combustion systems to some extent, the tools developed can potentially be applied to systems such as boilers, furnaces, and water heaters.

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