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Morphing materials and structures capable of assuming specific shapes under precise conditions have become increasingly relevant for numerous industries, including aerospace. However, a significant limitation of many proposed morphing materials and structures is their manufacturability. Furthermore, many morphing materials are not capable of supporting significant loads independently. It is therefore of interest to develop a methodology to generate support structures for morphing materials that can support specific desired shapes, and can be manufactured easily. This work proposes a methodology for optimizing compliant mechanisms that can be 3D printed using commercially available materials. These mechanisms are designed to lie behind traditional morphing materials such as shape-memory alloys, and assume a specific displacement profile when subjected to certain loading conditions. The methodology is tested on two separate displacement profiles and is compared with respect to buckling constraint severity., AIAA Scitech 2020 Forum, January 6-10, 2020, Orlando, FL

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities., ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Monday 11 June 2018, Oslo, Norway

The effects of altitude and fuel composition on gaseous and particle emissions from a turbojet engine were investigated as part of the National Jet Fuels Combustion Program (NJFCP) effort. Two conventional petroleum based jet fuels (a “nominal” and a “worst-case” jet fuel) and two test fuels with unique characteristics were selected for this study. The “worst-case” conventional jet fuel with high flash point and viscosity resulted in reduced combustion efficiency supported by the reduced CO2 emissions and corresponding increased CO and THC emissions. In addition, increased particle number (PN), particle mass (PM), and black carbon (BC) emissions were observed. Operating the engine on a bimodal fuel, composed of heavily branched C12 and C16 iso-paraffinic hydrocarbons with an extremely low cetane number did not significantly impact the engine performance or gaseous emissions but significantly reduced PN, PM, and BC emissions when compared to other fuels. The higher aromatic content and lower hydrogen content in the C-5 fuel were observed to increase PN, PM, and BC emissions. It is also evident that the type of aromatic hydrocarbons has a large impact on BC emissions. Reduction in combustion efficiency resulted in reduced CO2 emissions and increased CO and THC emissions from this engine with increasing altitudes. PN emissions were moderately influenced by altitude but PM and BC emissions were significantly reduced with increasing altitude. The reduced BC emissions with increasing altitude could be a result of reduced combustion temperature which lowered the rate of pyrolysis for BC formation, which is supported by the NOx reduction trend., ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, 26-30 June 2017, Charlotte, North Carolina, USA

The use of alternative fuels has the potential to enhance energy independence and reduce environmental impact of air travel. It is important to characterize gas turbine operation using such fuels under controlled conditions before implementing them in flight. The performance of a CF-700 engine core was examined in a sea level test facility. The following fuels were tested and will be reported on: 1. Jet A-1 - baseline fuel 2. 100% unblended Hydroprocessed Esters and Fatty Acids (HEFA) synthetic kerosene fuel with aromatics (SKA) 3. 100% unblended Fischer-Tropsch (FT) synthetic paraffinic kerosene (SPK) 4. Blended 50% HEFA-SPK and 50% Jet A-1 Fuel 2 above is an alternative fuel that can potentially be used without blending with conventional fuel. One purpose of the static engine testing was to determine if this fuel was suitable for use on subsequent test flights in a Dassault Falcon 20 aircraft. Engine performance testing was conducted at various power settings for each fuel. Relevant plots of performance are presented, compared and discussed. Transient tests were also performed including slams and chops. Observations of the effects of the different fuels on the engine fuel system are presented as some alternative fuels have the potential to cause seals to shrink and leaks to occur. The leaks observed are noted as are the steps taken to mitigate the problem., ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, GT 2015, 15 June 2015 through 19 June 2015

The motivation for the work comes from the requirement to assess the feasibility of using alternative fuels in lean-premixed land-based stationary gas turbine combustion systems. Lean-premixed systems are prone to combustion instability issues and the need is to determine how the use of alternative fuels would affect such instabilities. The paper presents the results of an acoustically-forced laminar flat flame study that was conducted to measure the influence of flow velocity oscillations on the response of syngas flames under various operating conditions and in comparison to natural gas flames. The results indicate that syngas concentration in a methane-syngas-air mixture significantly affects the flame response. On the other hand, the ratio of hydrogen-to-carbon monoxide in the syngas was found to have a negligible effect on the flame response for a fuel blend made up of 50% methane and 50% syngas. Flame liftoff distance and flame speed were found to be important parameters that govern the flame transfer function magnitude and resonant frequency for a thermally stabilized flat flame. The paper also presents insights into flame transfer function scaling based on a refined Strouhal definition., ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, June 16-20, 2014, Düsseldorf, Germany

Injection of bubbly gas flow into a liquid stream has wide application in chemical and biochemical industries. In these applications, generation of smaller bubble at higher frequency is desirable to achieve better reaction efficiency. We report on an experimental study conducted to investigate the bubble formation in liquid cross-flow using a novel nozzle design developed by Gadallah and Siddiqui [1]. This design is based on the creation of two side holes in the standard nozzle near the main nozzle hole. The experiments were performed in an acrylic square flow channel and high speed imaging was used to capture bubble dynamics. An image processing algorithm was used to quantify the size and frequency of detached bubbles and to track each individual bubble at different gas flow rates and liquid velocities. The results show that the new design of nozzle generates more bubbles of smaller size compared to the standard nozzle with no side hole at low liquid flow rates. It was observed that while the liquid velocity has crucial affect on the bubble size and detachment frequency from a standard nozzle, these parameters are weakly dependent on the liquid flow rate in the novel nozzle. The results show that at low liquid flow rates or in the stagnant liquid, the novel nozzle generates bubbles that are more than 20% smaller in size and more than two times faster compared to the standard nozzle. Copyright © 2013 by ASME and Her Majesty the Queen in Right of Canada., ASME 2013 Fluids Engineering Division Summer Meeting, FEDSM 2013, July 7-11, 2013, Incline Village, Nevada, USA, Series: FED

Adoption of hydro-processed esters and fatty acid biojet fuels is a critical component for the sustainability of the aviation industry. Aviation biofuels reduce pollution and provide alternatives to conventional fossil fuels. A study of the impacts of biofuels on emissions from a T56 turbo-prop engine was undertaken as a joint effort among several departments of the Government of Canada. In this study, particulate (including particle number and black carbon (BC) mass) and regulated gaseous emissions (CO2, CO, NO, NO 2, THC) were characterized with the engine operating on conventional F-34 jet fuel and jet fuel blended with camelina-based hydro-processed biojet fuel (C-HEFA) by 50% in volume. Emissions characterization, conducted after 20-hour ground engine durability tests, showed immediate significant reductions in particle number and BC mass when the engine was operated on the C-HEFA blend. Operating at high speed ground idle (HSGI) using the C-HEFA blend reduced particle number and BC mass emissions by 31% and 50%, respectively. At Take-off engine mode, particle number and BC mass reductions were 22% and 32%, respectively. In addition, particles generated from the C-HEFA blend were also observed to be slightly smaller than those generated from the conventional jet fuel by 2-4 nanometer (nm). CO emissions from the C-HEFA blend were lower by 4-6%. CO2 emissions from the C-HEFA blend were lower by approximately 1%, consistent with the difference in hydrocarbon ratios in the C-HEFA blend., SAE 2013 AeroTech Congress and Exhibition, AEROTECH 2013, 24 September 2013 through 26 September 2013, Montreal, QC

To enhance energy security and reduce the environmental impact of aviation, alternate fuels derived from various nonpetroleum based sources are being developed. Currently alternate fuels are produced to match the properties of existing jet fuels allowing the new fuels to be used in current fleets concurrently with traditional jet fuel. The alternate fuels must, therefore, perform as well as the traditional fuels through the entire operating envelope. This paper provides the results of performance testing in an altitude chamber up to 11,300 m (35,000 feet) with a simulated forward speed up to Mach 0.75. The test engine was an instrumented 1.15 kN thrust turbojet burning conventional Jet A-1 as a baseline; a semi-synthetic blend of camelina based hydro processed renewable jet and JP8; a blend of 50% Fischer-Tropsch synthetic paraffinic kerosene and 50% JP8; and a 100% Fischer-Tropsch synthetic paraffinic kerosene. Both steady state and transient performance are presented. The theoretical effect of the alternate fuels for a simple idealized Brayton cycle is also presented. The work was conducted as part of on-going efforts by departments within the Government of Canada to systematically assess alternative aviation fuels., ASME TurboExpo 2011: Power for Land, Sea, and Air, 6-10 June 2011, Vancouver, Canada

Gas injection into a liquid cross flow from a nozzle causes bubble formations which have potential applications in industry such as chemical plants, waste water treatment and bio- and nuclear-reactors. The purpose of this study is to experimentally investigate the effects of nozzle shape and configuration with respect to the liquid cross-flow direction, on the bubbly flow characteristics such as bubble formation, detached bubble size and frequency at different gas and liquid flow rates. The experiments were conducted in a Plexiglas two-dimensional rig using a high speed camera. High speed imaging and an image processing algorithm were used to track each individual bubble and to quantify the bubble growth as well as the detachment frequency and the bubble velocity. Back light shadowgraphy which utilizes a low intensity diffuse light source to illuminate the background was used to image bubbles. Nozzles were mounted in the test section which was designed such that the flow in this section has a two-dimensional profile. The results showed that the bubble size increases with an increase in GLR (gas to liquid flow rates ratio). Furthermore, the bubble formations and detached bubble size were strongly influenced by the nozzle shape and configuration. Copyright © 2012 by ASME., ASME 2012 Fluids Engineering Division Summer Meeting, FEDSM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and M, FEDSM 2012, 8 July 2012 through 12 July 2012, Rio Grande

Dry low emissions premixed combustion systems have the ability to give larger NOx emissions reduction in comparison to diffusion type of combustors. However, these systems are prone to flashback because the fuel and oxidizers are mixed upstream of the combustion chamber. This is particularly true for premixed systems burning high-reactivity fuels due to their higher flame speed. Flashback is undesirable in gas turbines because it leads to overheating and failure of fuel nozzles and premixing sections. Recently, a novel application of Plasma Actuation through non-thermal Dielectric Barrier Discharge has been shown to significantly delay flashback in the core flow along the axis of the premixer. Building on this successful endeavour, efforts were directed to prove the effectiveness of the control method in situations where flashback was triggered in the boundary layer. Results show that the current application delays the occurrence of flashback in the boundary layer of the premixer to higher equivalence ratios. Improvements in the combustor operability margin of 10 to 14% when burning natural gas-air mixtures, and of about 3.5% when replacing the fuel by an equimolar mixture of natural gas and hydrogen, were achieved. It was found that the proposed application of plasma actuation is even more efficient in preventing flashback in the boundary layer than in the core flow., ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012, June 11-15, 2012, Copenhagen, Denmark

Thermoacoustic instabilities in combustors have remained a topic of investigation for over a few decades due to the challenges it posses to the operation of low emission gas turbines. For combustors burning liquid fuel, understanding the cause-andeffect relationship between spray combustion dynamics and thermoacoustic oscillations is imperative for the successful development of any control methodology for its mitigation. The paper presents some very unique operating characteristics of a kerosene-fueled diffusion type combustor undergoing limit-cycle oscillations. Combustor stability limits were mapped using three different-sized injectors. The results show that combustor instability depends on the characteristics of the fuel spray. A simple analytic analysis is also reported in support of a plausible explanation for the unique combustor behavior. The study indicates that high amplitude acoustic pressure in the combustor may cause secondary breakdown of fuel droplets resulting in premixed pre-vaporized type burning of the diffusion type combustor., {"references":["J. C. Solt, J. Tuzson, Proceedings of 1993 ASME IGTI Conference\nPaper 93-GT-270, 1993.","T. Lieuwen, B. T. Zinn, AIAA 36th Aerospace Sciences Meeting &\nExhibit Paper 98-0641, 1998.","A. Y. Tong, W. A. Sirignano, Journal of Propulsion and Power 5(3)\n(1989) 257-261.","W. A. Chishty, Effects of Thermoacoustic Oscillations on Spray\nCombustion Dynamics with Implications for Lean Direct Injection\nSystems, PhD thesis, Virginia Polytechnic Institute and State University,\nBlacksburg, VA, USA, 2005.","A. M. Mellor, Design of Modern Turbine Combustors, Academic Press\nLimited, 1990.","C. Clanet, G. Searby, P. Clavin, Journal of Fluid Mechanics 385 (1999)\n157-197.","S. Dowson, J. Fitzpatrick, Journal of Sound and Vibration 230(3) (2000)\n649-660.","A. V. Anilkumar, C. P. Lee, T. G. Wang, NASA Conference Publication\n3338, (1996) 559-564.","R. Schmehl, G. Klose, G. Maier, S. Wittig, S., NATO RTO Gas Turbine\nEngine Combustion, Emissions and Alternate Fuels, 1999.\n[10] P. J. O-Rourke, A. A. Amsden, SAE Technical Report 872089, 1987.\n[11] J.-H. Park, Y. Yoon, Atomization and Sprays 12 (2002) 387- 401."]}

To address the global fuel challenges of energy security, economic sustainability and climate change the stakeholders of aviation industry are actively pursuing the development and qualification of alternative 'drop-in' fuels. New standards will be required to regulate the use of these new fuels, which requires not only fuel specification and rig/engine and flight testing but also an emission life cycle impact assessment of these fuels. This paper reports on emission data measured at various simulated altitudes and engine speeds from a jet engine operated on conventional and alternative aviation fuels. The work was conducted as part of on-going efforts by departments within the Government of Canada to systematically assess regulated as well as non-regulated emissions from the use of alternative aviation fuels. The measurements were performed on an instrumented 1000 N-thrust turbojet engine using a baseline conventional Jet A-1 fuel and a semisynthetic (50/50) blend with Camelina based Hydroprocessed Renewable Jet (JP8-HRJ8) fuel. Emission results reported here include carbon dioxide, carbon monoxide, nitrogen oxides and particulate matter measured at several simulated altitudes and power settings. In order to ensure that the assessments have a common baseline, relevant engine performance and operability data were also recorded. Copyright © 2011 by ASME., ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, GT2011, 6 June 2011 through 10 June 2011, Vancouver, BC

Gaseous and particle emission assessments on a 1.15 kN-thrust turbojet engine were conducted at five altitudes in an altitude chamber with Jet A-1 fuel, pure Fischer Tropsch (FT), and two mixed fuels of JP-8 with FT or Camelina based hydro-processed jet fuels. In general, lower emissions in CO2, NOx, and particle number as well as higher emissions in CO and THC were observed at higher altitudes compared to lower altitudes. These observations, which were similar for all test fuels, were attributed to the reduced combustion efficiency and temperature at higher altitudes. The use of alternative fuels resulted in lower CO2 emissions, ranging from 0.7% to 1.7% for 50% to 100% synthetic fuel in the fuel mixture at various altitudes. In terms of CO, the use of 100% FT fuel resulted in CO reduction up to 9.7% at 1525 m altitude and up to 5.9% at 9145 m altitude. Significant reduction in particle diameter, number and mass emission rates were observed with the use of alternative fuels due to the low aromatic and sulfur content in the fuels. Higher reductions were observed for increasing percentage of the alternative synthetic fuel in the fuel mixture. With the use of pure FT fuel, up to 80% and 96% reductions in particle number emissions were observed at 1525 m and 9145 m altitudes, respectively. In comparison, a larger particle reduction benefit was observed for the Camelina based hydro-processed jet fuel than for the FT fuel., SAE 2011 AeroTech Congress and Exhibition, AEROTECH 2011, 18 October 2011 through 21 October 2011, Toulouse