Journal articles on the topic 'Propulsion spray'
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Richecoeur, Franck, and Sébastien Candel. "Combustion, spray and flow dynamics for aerospace propulsion." Comptes Rendus Mécanique 341, no. 1-2 (January 2013): 1–3. http://dx.doi.org/10.1016/j.crme.2012.11.011.
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Bartlett, C. S. "Turbine Engine Icing Spray Bar Design Issues." Journal of Engineering for Gas Turbines and Power 117, no. 3 (July 1, 1995): 406–12. http://dx.doi.org/10.1115/1.2814110.
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Techniques have been developed at the Engine Test Facility (ETF) of the Arnold Engineering Development Center (AEDC) to simulate flight through atmospheric icing conditions of supercooled liquid water droplets. Ice formed on aircraft and propulsion system surfaces during flight through icing conditions can, even in small amounts, be extremely hazardous. The effects of ice are dependent on many variables and are still unpredictable. Often, experiments are conducted to determine the characteristics of the aircraft and its propulsion system in an icing environment. Facilities at the ETF provide the capability to conduct icing testing in either the direct-connect (connected pipe) or the free-jet mode. The requirements of a spray system for turbine engine icing testing are described, as are the techniques used at the AEDC ETF to simulate flight in icing conditions. Some of the key issues facing the designer of a spray system for use in an altitude facility are identified and discussed, and validation testing of the design of a new spray system for the AEDC ETF is detailed. This spray system enables testing of the newest generation of high-thrust turbofan engines in simulated icing conditions.
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Naghdi, P. M., and M. B. Rubin. "The Effects of Energy Dissipation on the Transition to Planing of a Boat." Journal of Ship Research 33, no. 01 (March 1, 1989): 35–46. http://dx.doi.org/10.5957/jsr.1989.33.1.35.
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The problem of the transition to planing of a boat, in the presence of the effect of spray formation at the boat's leading edge, is investigated using a nonlinear steady-state solution of the equations of the theory of a directed fluid sheet for two-dimensional motion of an incompressible inviscid fluid. The motion of the fluid is coupled with the motion of the free-floating boat and detailed analysis is undertaken pertaining to such features as trim angle, sinkage, and propulsion force. The effects of the rate of energy dissipation arising from spray formation at the boat's leading edge, and changes in equilibrium depth, propulsion angle, and the boat's weight, are studied and shown to significantly influence the boat's planing characteristics.
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WANG, JIANGFENG, CHEN LIU, and YIZHAO WU. "NUMERICAL SIMULATION OF SPRAY ATOMIZATION IN SUPERSONIC FLOWS." Modern Physics Letters B 24, no. 13 (May 30, 2010): 1299–302. http://dx.doi.org/10.1142/s0217984910023475.
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With the rapid development of the air-breathing hypersonic vehicle design, an accurate description of the combustion properties becomes more and more important, where one of the key techniques is the procedure of the liquid fuel mixing, atomizing and burning coupled with the supersonic crossflow in the combustion chamber. The movement and distribution of the liquid fuel droplets in the combustion chamber will influence greatly the combustion properties, as well as the propulsion performance of the ramjet/scramjet engine. In this paper, numerical simulation methods on unstructured hybrid meshes were carried out for liquid spray atomization in supersonic crossflows. The Kelvin-Helmholtz/Rayleigh-Taylor hybrid model was used to simulate the breakup process of the liquid spray in a supersonic crossflow with Mach number 1.94. Various spray properties, including spray penetration height, droplet size distribution, were quantitatively compared with experimental results. In addition, numerical results of the complex shock wave structure induced by the presence of liquid spray were illustrated and discussed.
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Wu, Jinxin, Li Cheng, Can Luo, and Chuan Wang. "Influence of External Jet on Hydraulic Performance and Flow Field Characteristics of Water Jet Propulsion Pump Device." Shock and Vibration 2021 (May 24, 2021): 1–15. http://dx.doi.org/10.1155/2021/6690910.
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Water jet propulsion technology has broad application prospects in the field of ships, and water jet technology is a kind of high and new technology that is booming and has a wide range of applications. However, there are a few studies on the effect of the external jet on the performance of the water jet propulsion pump, and it is urgent to carry out this research. In this paper, the standard k-ε turbulence model is used to carry out the numerical simulation study of the influence of the external jet on the hydraulic performance and flow field characteristics of the water jet propulsion pump device. This paper discusses the selection of calculation models, the division of grids and the setting of turbulence models, and an in-depth analysis of the calculation results. The research results show that when a high-speed water jet enters a moving water body, it will cause turbulence in the moving water body. With the increase of jet flow, the turbulence phenomenon will be improved. The average velocity of the outlet section of the nozzle is consistent with the change of the total pressure. The average vortex gradually decreases, the turbulent kinetic energy changes little, the turbulence dissipation first decreases and then increases, and the nozzle axial force changes more and more. The axial force and thrust of the device will obviously increase when the two water streams merge and spray, and they will increase with the increase of the jet flow rate. By revealing the influence mechanism of the external jet on the water jet propulsion pump device, it can provide a theoretical basis and guiding direction for further optimizing the hydraulic performance of the entire device.
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Li, Bo, Huang Kuo, Xuehui Wang, Yiyi Chen, Yangang Wang, David Gerada, Sean Worall, Ian Stone, and Yuying Yan. "Thermal Management of Electrified Propulsion System for Low-Carbon Vehicles." Automotive Innovation 3, no. 4 (December 2020): 299–316. http://dx.doi.org/10.1007/s42154-020-00124-y.
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AbstractAn overview of current thermal challenges in transport electrification is introduced in order to underpin the research developments and trends of recent thermal management techniques. Currently, explorations of intelligent thermal management and control strategies prevail among car manufacturers in the context of climate change and global warming impacts. Therefore, major cutting-edge systematic approaches in electrified powertrain are summarized in the first place. In particular, the important role of heating, ventilation and air-condition system (HVAC) is emphasised. The trends in developing efficient HVAC system for future electrified powertrain are analysed. Then electric machine efficiency is under spotlight which could be improved by introducing new thermal management techniques and strengthening the efforts of driveline integrations. The demanded integration efforts are expected to provide better value per volume, or more power output/torque per unit with smaller form factor. Driven by demands, major thermal issues of high-power density machines are raised including the comprehensive understanding of thermal path, and multiphysics challenges are addressed whilst embedding power electronic semiconductors, non-isotropic electromagnetic materials and thermal insulation materials. Last but not least, the present review has listed several typical cooling techniques such as liquid cooling jacket, impingement/spray cooling and immersion cooling that could be applied to facilitate the development of integrated electric machine, and a mechanic-electric-thermal holistic approach is suggested at early design phase. Conclusively, a brief summary of the emerging new cooling techniques is presented and the keys to a successful integration are concluded.
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Sutrisno, Avando Bastari, and Okol Sri Suharyo. "Enviromental Pattern Analysis of Biodiesel (Castor, Coconut, MGB) to Support Alternative Energy using CFD approach." Global Journal of Engineering and Technology Advances 8, no. 1 (July 30, 2021): 051–60. http://dx.doi.org/10.30574/gjeta.2021.8.1.0100.
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The Ship uses the MTU 16V956 TB 92 propulsion engine with a piston-type Mexican Hat combustion chamber. In general, the crown is used on machines with large torque. Besides that, the crown shape in the combustion chamber is also very influential on the formation of a mixture of fuel and air before the combustion process occurs. So it is necessary to know about the spray pattern of biodiesel fuel of enviromental things (castor, coconut, used cooking oil/MGB) in the Mexican Hat combustion chamber. In this study, using the Mexican Hat-shaped piston crown simulation method, the first step was to test the spray pattern of the three types of biodiesel (castor, coconut, used cooking oil) by simulating a tube with an injection pressure of 350 bar gauge pressure inside a barometric pressure tube. While the completion in the Mexican Hat combustion chamber with a chamber pressure of 35 bar gauge and injection pressure of 350 bar gauge was completed with the CFD program, Fluent 6.2, and the results of the three biodiesels were compared. From the CFD simulation results obtained spray patterns of the three types of biodiesel (castor, coconut, used cooking oil). At the same injection pressure and chamber pressure, used cooking biodiesel has the longest penetration length, followed by castor biodiesel and coconut biodiesel. The spray angle of coconut biodiesel is the largest, followed by castor biodiesel and used cooking oil biodiesel. SMD coconut biodiesel is the smallest, followed by castor biodiesel and used cooking oil biodiesel.
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Yu, Weigang, Zhiqing Zhang, and Bo Liu. "Investigation on the Performance Enhancement and Emission Reduction of a Biodiesel Fueled Diesel Engine Based on an Improved Entire Diesel Engine Simulation Model." Processes 9, no. 1 (January 6, 2021): 104. http://dx.doi.org/10.3390/pr9010104.
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In order to improve the efficiency of the diesel engine and reduce emissions, an improved heat transfer model was developed in an AVL-BOOST environment which is a powerful and user-friendly software for engine steady-state and transient performance analysis. The improved heat transfer model considers the advantages of the Woschni1978 heat transfer model and Honhenberg heat transfer model. In addition, a five-component biodiesel skeletal mechanism containing 475 reactions and 134 species was developed to simulate the fuel spray process and combustion process since it contained methyl linolenate, methyl linoleate, methyl oleate, methyl stearate, and methyl palmitate, which are a majority component in most biodiesel. Finally, the propulsion and load characteristics of a diesel engine fueled with biodiesel fuel were investigated by the improved heat transfer model in term of power, brake specific fuel consumption (BSFC), soot and NOx emissions. Similarly, the effects of the fuel injection rate on the diesel engine’s characteristic fueled with biodiesel was studied. The result showed that the errors between experiment and simulation were less than 2%. Thus, the simulation model could predict the propulsion and load characteristics of the diesel engine. The nozzle diameter, injection pressure, and injection advance angle are significant to the injection system. Thus, it is very important to choose the injection rate reasonably.
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Lefebvre, A. H. "Fuel Effects on Gas Turbine Combustion—Ignition, Stability, and Combustion Efficiency." Journal of Engineering for Gas Turbines and Power 107, no. 1 (January 1, 1985): 24–37. http://dx.doi.org/10.1115/1.3239693.
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An analytical study is made of the substantial body of experimental data acquired during recent Wright-Patterson Aero Propulsion Laboratory sponsored programs on the effects of fuel properties on the performance and reliability of several gas turbine combustors, including J79-17A, J79–17C (Smokeless), F101, TF41, TF39, J85, TF33, and F100. Quantitative relationships are derived between certain key aspects of combustion, notably combustion efficiency, lean blowout limits and lean light-off limits, and the relevant fuel properties, combustor design features, and combustor operating conditions. It is concluded that combustion efficiency, lean blowout limits, and lean lightoff limits are only slightly dependent on fuel chemistry, but are strongly influenced by the physical fuel properties that govern atomization quality and spray evaporation rates.
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Vinogradov, Viacheslav A., Yurii M. Shikhman, and Corin Segal. "A Review of Fuel Pre-injection in Supersonic, Chemically Reacting Flows." Applied Mechanics Reviews 60, no. 4 (July 1, 2007): 139–48. http://dx.doi.org/10.1115/1.2750346.
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Developing an efficient, supersonic combustion-based, air breathing propulsion cycle operating above Mach 3.5, especially when conventional hydrocarbon fuels are sought and particularly when liquid fuels are preferred to increase density, requires mostly effective mechanisms to improve mixing efficiency. One way to extend the time available for mixing is to inject part of the fuel upstream of the vehicle’s combustion chamber. Injection from the wall remains one of the most challenging problems in supersonic aerodynamics, including the requirement to minimize impulse losses, improve fuel-air mixing, reduce inlet∕combustor interactions, and promote flame stability. This article presents a review of studies involving liquid and, in selected cases, gaseous fuel injected in supersonic inlets or in combustor’s insulators. In all these studies, the fuel was injected from a wall in a wake of thin swept pylons at low dynamic pressure ratios (qjet∕qair=0.6–1.5), including individual pylon∕injector geometries and combinations in the inlet and combustor’s isolator, a variety of injection conditions, different injectants, and evaluated their effects on fuel plume spray, impulse losses, and mixing efficiency. This review article cites 47 references.
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Trussell, Nicholas, and Stefan Jacobsen. "Review of Sprayability of Wet Sprayed Concrete." Nordic Concrete Research 63, no. 2 (December 1, 2020): 21–41. http://dx.doi.org/10.2478/ncr-2020-0016.
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Abstract Wet sprayed concrete quality is affected by more production factors than cast concrete, particularly due to the propulsion through the nozzle and the flash set caused by the set accelerator. Practitioners often use the term “sprayability” to describe these factors. We propose a definition of “sprayability” that relates the application to the final properties of the hardened sprayed concrete and review factors affecting it: concrete constituents, proportioning, and application mechanics. These factors affect the hardening and the structure of the hardened sprayed concrete – the porosity, permeability and durability. We consider improving sustainability through proportioning with increased share of supplementary cementitious materials, calculate the placed composition and focus on factors that affect water transport, and hence durability. Due to the spray application and flash-set, irregular compaction voids dominate the macro pore structure of sprayed concrete. Studies of permeability of sprayed concrete have shown that it is possible to obtain low permeabilities given adequate composition and curing. Presumably these samples have been well-cured, uncracked and with non-percolating macro voids. Given observations of cracks in sprayed concrete linings and the macro voids, important further studies will be on the effect of accelerator, compaction porosity and cracking on permeability.
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Myers, G. D., J. P. Armstrong, C. D. White, S. Clouser, and R. J. Harvey. "Development of an Innovative High-Temperature Gas Turbine Fuel Nozzle." Journal of Engineering for Gas Turbines and Power 114, no. 2 (April 1, 1992): 401–8. http://dx.doi.org/10.1115/1.2906605.
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The objective of the innovative high-temperature fuel nozzle program was to design, fabricate, and test propulsion engine fuel nozzles capable of performance despite extreme fuel and air inlet temperatures. Although a variety of both passive and active methods for reducing fuel wetted-surface temperatures were studied, simple thermal barriers were found to offer the best combination of operability, cycle flexibility, and performance. A separate nozzle material study examined several nonmetallics and coating schemes for evidence of passivating or catalytic tendencies. Two pilotless airblast nozzles were developed by employing finite-element modeling to optimize thermal barriers in the stem and tip. Operability of these prototypes was compared to a current state-of-the art piloted, prefliming airblast nozzle, both on the spray bench and through testing in a can-type combustor. The three nozzles were then equipped with internal thermocouples and operated at 1600°F air inlet temperature while injecting marine diesel fuel heated to 350°F. Measured and predicted internal temperatures as a function of fuel flow rate were compared. Results show that the thermal barrier systems dramatically reduced wetted-surface temperatures and the potential for coke fouling, even in an extreme environment.
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Kumar, Amarnath, Jenna Moledina, Yuan Liu, Kuiying Chen, and Prakash C. Patnaik. "Nano-Micro-Structured 6%–8% YSZ Thermal Barrier Coatings: A Comprehensive Review of Comparative Performance Analysis." Coatings 11, no. 12 (November 30, 2021): 1474. http://dx.doi.org/10.3390/coatings11121474.
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Beneficial properties achieved by nanostructuring effects in materials have generated tremendous interests in applications in surface engineering, especially in thermal barrier coatings (TBC). Limitations in conventional TBC processing for gas turbines and aero-propulsion systems have been exposed during past decades when rapid progress was made in nano-structuring coating research and developments. The present work is a comprehensive review of the current state of progress in nanostructured TBC (Ntbc) in reference to its microstructure, damage progression, failure mechanisms and a wide range of properties. The review aims to address the comparative performance analysis between the nanostructured and conventional (microstructured) 6–8 wt.% yttrium stabilized zirconia (YSZ) TBC systems. Oxidation resistance and sintering behavior in two TBCs are considered as the central focus of discussion. A few schematics are used to represent major microstructural features and failure progression. A performance analysis is performed for standard 2-layer, as well as functionally graded multilayer, TBC systems. A comparison of TBC characteristics processed by plasma spray and vapor deposition techniques is also made as reference. Compared to the sea of R&D efforts made for conventional TBC (Ctbc), limited experimental studies on Ntbc offers conflicting data, and prediction modeling and computational research are scarce.
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Sahranavardfard, Nasrin, Adrian Pandal, Faniry Nadia Zazaravaka Rahantamialisoa, and Michele Battistoni. "A Study on Accounting for Drift Velocities on Liquid Jets Injected in Cross Flow." Journal of Physics: Conference Series 2385, no. 1 (December 1, 2022): 012136. http://dx.doi.org/10.1088/1742-6596/2385/1/012136.
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Abstract The efficiency and combustion performance of propulsion systems, like internal combustion (IC) engines and gas turbines, is known to be related to the performance of the fuel and air mixing process. Operating conditions and fuels are rapidly changing, therefore new CFD models which accurately accounts for all physical aspects, still maintaining a simple framework, are extremely important. In this work we consider the drift velocity contribution, which often is overlooked or neglected, defined as the velocity of the dispersed phase relative to the mixture volumetric mean velocity in a single fluid formulation, a key variable in two-phase mixture model. Water test cases are here considered for the study. The present work investigates the structure and the droplet velocity field of a plain liquid jet injected into a high-pressure air crossflow. Because of the large scale separation between the small features of the interface and the overall jet we use the diffuse-interface treatment in a single-fluid Eulerian framework. A Σ- Y family model is implemented in the OpenFOAM framework which includes liquid diffusion due to drift-flux velocities and a new formulation of the spray atomization. The main objective is to explore the droplet velocity distribution and the jet structure with and without considering the drift flux correction and compare the related results with the experimental data.
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Monsalve-Serrano, Javier, Giacomo Belgiorno, Gabriele Di Blasio, and María Guzmán-Mendoza. "1D Simulation and Experimental Analysis on the Effects of the Injection Parameters in Methane–Diesel Dual-Fuel Combustion." Energies 13, no. 14 (July 20, 2020): 3734. http://dx.doi.org/10.3390/en13143734.
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Notwithstanding the policies that move towards electrified powertrains, the transportation sector mainly employs internal combustion engines as the primary propulsion system. In this regard, for medium- to heavy-duty applications, as well as for on- and off-road applications, diesel engines are preferred because of the better efficiency, lower CO2, and greater robustness compared to spark-ignition engines. Due to its use at a large scale, the internal combustion engines as a source of energy depletion and pollutant emissions must further improved. In this sense, the adoption of alternative combustion concepts using cleaner fuels than diesel (e.g., natural gas, ethanol and methanol) presents a viable solution for improving the efficiency and emissions of the future powertrains. Particularly, the methane–diesel dual-fuel concept represents a possible solution for compression ignition engines because the use of the low-carbon methane fuel, a main constituent of natural gas, as primary fuel significantly reduces the CO2 emissions compared to conventional liquid fuels. Nonetheless, other issues concerning higher total hydrocarbon (THC) and CO emissions, mainly at low load conditions, are found. To minimize this issue, this research paper evaluates, through a new and alternative approach, the effects of different engine control parameters, such as rail pressure, pilot quantity, start of injection and premixed ratio in terms of efficiency and emissions, and compared to the conventional diesel combustion mode. Indeed, for a deeper understanding of the results, a 1-Dimensional spray model is used to model the air-fuel mixing phenomenon in response to the variations of the calibration parameters that condition the subsequent dual-fuel combustion evolution. Specific variation settings, in terms of premixed ratio, injection pressure, pilot quantity and combustion phasing are proposed for further efficiency improvements.
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Doustdar, Mohammad Mahdi, and Mohammad Mojtahedpoor. "A Numerical Study of the Effect of Injection Velocity on Fuel Droplets Sizing in a Three-Dimensional Side-Dump Combustor." Applied Mechanics and Materials 52-54 (March 2011): 2045–50. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.2045.
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The effects of injection velocity on propulsive droplets sizing and efficient mass fraction in a three dimensional side-dump combustor with dual opposite curved side-inlet duct are numerically investigated in the present paper. The mass of fuel vapor inside the flammability limit is named efficient mass fraction. The air flow comes from side-inlet ducts into the cylindrical combustor and four nozzles which are located in the top of the cylinder have the duties of fuel injection. The injection velocity is varied as 20, 40, 60 and 80 [m/s] respectively to examine its effects on propulsive droplets sizing and efficient mass fraction which provides worthwhile information for the combustor design work. As well, by increasing entrance air flow velocity from 35 to 100 and 280[m/s] correspondingly, these computations are repeated. To fulfill the calculations a modified version of KIVA-3V code which is a transient, three-dimensional, multiphase, multicomponent code for the analysis of chemically reacting flows with sprays, is used.
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Doustdar, Mohammad Mahdi, and Mohammad Mojtahedpoor. "A Numerical Study of the Effect of Pressure on Propulsive Droplets Sizing in a Duct by KIVA-3V Code." Applied Mechanics and Materials 110-116 (October 2011): 4527–31. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4527.
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The size of fuel propulsive droplets is one of the effective parameter in improvement of the mixture of air and fuel as well as combustion. The effects of Pressure on the average diameter of fuel propulsive droplets sizing and effective mass fraction in a duct are numerically investigated in the present paper. We named the mass of fuel vapor inside the flammability limit as the efficient mass fraction. The inlet pressure of entrance airflow is varied as 1, 2, 3, 4 and 5 (atm) to examine its effects on the fuel droplets and fuel/air mixing phenomena. As well, by growing the entrance air flow velocity from 36 to 50 (m/s) we have repeated this test again, which provides worthwhile information for the combustor design work. To fulfill the calculations a modified version of KIVA-3V code which is a transient, three-dimensional, multiphase, multicomponent code for the analysis of chemically reacting flows with sprays, is used.
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Cao, Congcong, Wenya Li, Zhengmao Zhang, Xiawei Yang, and Yaxin Xu. "Cold Spray Additive Manufacturing of Ti6Al4V: Special Nozzle Design Using Numerical Simulation and Experimental Validation." Coatings 12, no. 2 (February 6, 2022): 210. http://dx.doi.org/10.3390/coatings12020210.
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Cold spray additive manufacturing (CSAM) shows great potential in titanium-alloy production as it is a solid-state process. However, data published so far have demonstrated the difficulty of producing dense and high-strength Ti alloy parts. Our previous studies have shown that nozzle design together with high-cost helium propulsive gas plays a crucial role in particle acceleration. In this work, special nozzles for Ti alloy were designed and validated experimentally with commercially available Ti6Al4V powder. Simulation results show that particle impact temperature increases remarkably for a long convergent length, while particle kinetic energy slightly increases, which is validated by experiments. The relationship between the particle impact temperature and practice diameter shows the first increase and then decrease. The experimental results show that as the nozzle convergent section becomes longer, the edges of the single-pass deposits become smoother, and the width, density, deposition efficiency, and microhardness of the single-pass deposits increase.
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Biagi, Roberto, Elisa Verna, Edoardo Bemborad, Maurizio Galetto, Shuo Yin, and Rocco Lupoi. "Cold Spraying of IN 718-Ni Composite Coatings: Microstructure Characterization and Tribological Performance." Materials Science Forum 1016 (January 2021): 840–45. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.840.
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INCONEL 718 superalloy (IN 718) is frequently used in highly aggressive environments, such as aerospace and gas turbine engines, where excellent mechanical properties, creep-, fatigue- and oxidation-resistance performance at high and cryogenic temperatures are required. Recent studies have successfully cold sprayed IN 718, showing great potential mainly in maintenance and repairing fields. However, due to the low plastic deformation, the manufacture of IN 718 cold sprayed coatings often requires the use of expensive propulsive gases or high working parameters to enhance deposition efficiency, with a significant increase in production costs. This paper investigates for the first time the addition of Ni to IN 718 powders in order to increase plastic deformation and interparticle bonding strength. Four composite coatings were deposited via a high-pressure cold spray process using nitrogen as propulsive gas, considering different IN 718 mass fractions in the feedstock: C1 (0 wt%), C2 (25 wt%), C3 (50 wt%), C4 (75 wt%). The coatings are examined in terms of microstructural characteristics and tribological performance. The addition of IN 718 particles significantly improves the mechanical properties of the coatings, despite an increase in porosity, which however does not exceed 1%. The tribological performance of the four coatings is investigated using a pin-on-disk test, demonstrating that the coating wear resistance behaviour improved as the IN 718 content increased. Analysis of the wear mechanism shows that C4 coating has a different wear behaviour than the other coatings, thus achieving the best wear-resistance performance.
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Nguyen, Khoi, Ning Yu, Mahesh M. Bandi, Madhusudhan Venkadesan, and Shreyas Mandre. "Curvature-induced stiffening of a fish fin." Journal of The Royal Society Interface 14, no. 130 (May 2017): 20170247. http://dx.doi.org/10.1098/rsif.2017.0247.
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How fish modulate their fin stiffness during locomotive manoeuvres remains unknown. We show that changing the fin's curvature modulates its stiffness. Modelling the fin as bendable bony rays held together by a membrane, we deduce that fin curvature is manifested as a misalignment of the principal bending axes between neighbouring rays. An external force causes neighbouring rays to bend and splay apart, and thus stretches the membrane. This coupling between bending the rays and stretching the membrane underlies the increase in stiffness. Using three-dimensional reconstruction of a mackerel ( Scomber japonicus ) pectoral fin for illustration, we calculate the range of stiffnesses this fin is expected to span by changing curvature. The three-dimensional reconstruction shows that, even in its geometrically flat state, a functional curvature is embedded within the fin microstructure owing to the morphology of individual rays. As the ability of a propulsive surface to transmit force to the surrounding fluid is limited by its stiffness, the fin curvature controls the coupling between the fish and its surrounding fluid. Thereby, our results provide mechanical underpinnings and morphological predictions for the hypothesis that the spanned range of fin stiffnesses correlates with the behaviour and the ecological niche of the fish.
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Collins, George, and Donald J. Rej. "Plasma Processing of Advanced Materials." MRS Bulletin 21, no. 8 (August 1996): 26–31. http://dx.doi.org/10.1557/s0883769400035673.
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A plasma, commonly referred to as the “fourth state of matter,” is an ensemble of randomly moving charged particles with a sufficient particle density to remain, on average, electrically neutral. While their scientific study dates from the 19th century, plasmas are ubiquitous, comprising more than 99% of the known material universe. The term “plasma” was first coined in the 1920s by Irving Langmuir at the General Electric Company after the vague resemblance of a filamented glow discharge to a biological plasma.Plasmas are studied for many reasons. Physicists analyze the collective dynamics of ions and electron ensembles, utilizing principals of classical electromagnetics, and fluid and statistical mechanics, to better understand astrophysical, solar, and ionospheric phenomenon, and in applied problems such as thermonuclear fusion. Electrical engineers use plasmas to develop efficient lighting, and high-power electrical switchgear, and for magneto-hydrodynamic (MHD) power conversion. Aerospace engineers apply plasmas for attitude adjustment and electric propulsion of satellites. Chemists, chemical engineers, and materials scientists routinely use plasmas in reactive ion etching and sputter deposition. These methods are commonplace in microelec tronics since they allow synthesis of complex material structures with submicron feature sizes. A substantial portion of the multi-billion-dollar market for tooling used to manufacture semiconductors employs some form of plasma process. When compared with traditional wet-chemistry techniques, these dry processes result in minimal waste generation. Plasmas are also useful in bulk processing—for example as thermal sprays for melting materials.While the quest for controlled thermonuclear fusion dominated much of plasma research in the 1960s and 1970s, in the last 20 years it has been the application of plasmas to materials processing that has provided new challenges for many plasma practitioners. It is not surprising that the guest editors and several of the authors for this issue of MRS Bulletin come from a fusion plasma-physics background.
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GUERRERO, I., R. BOCANEGRA, F. J. HIGUERA, and J. FERNANDEZ DE LA MORA. "Ion evaporation from Taylor cones of propylene carbonate mixed with ionic liquids." Journal of Fluid Mechanics 591 (October 30, 2007): 437–59. http://dx.doi.org/10.1017/s0022112007008348.
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A combined experimental and numerical approach is used to extract information on the kinetics of ion evaporation from the region of high electric field around the tip of a Taylor cone of the neutral solvent propylene carbonate (PC) mixed with two ionic liquids. On the numerical side, the electric field on the surface of the liquid is computed in the absence of evaporation by solving the electrohydrodynamic problem in this region within the framework of the leaky dielectric model. These computations justify the approximate (2% max error) scaling Emax = β Ek for the maximum electric field on the surface, with Ek = γ1/2 ϵ0−2/3 (K/Q)1/6 for 0.111 < K < 0.888 S m−1 and a numerical value of β ≈ 0.76. Here γ is the surface tension of PC, ϵ0 is the electrical permittivity of vacuum, and K and Q are the liquid electrical conductivity and flow rate. On the experimental side, 16 different propylene carbonate solutions with either of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) or EMI-bis(trifluoro-methylsulfonyl)imide (EMI-Im) are electrosprayed in a vacuum from a single Taylor cone, and their emissions of charged drops and ions are analysed by time-of-flight mass spectrometry at varying liquid flow rates Q. The sprays contain exclusively drops at large Q, both for small and for large electrical conductivities K, but enter a mixed ion–drop regime at sufficiently large K and small Q. Interestingly, the mixtures containing 10% and 15% (vol) EMI-Im exhibit no measurable ion currents at high Q, but approach a purely ionic regime (almost no drops) at small Q. The charge/mass ratio for the drops produced in these two mixtures increases continuously with decreasing Q, and gets very close to ionic values. Measured ion currents are represented versus computed maximum electric fields Emax on the liquid surface to infer ion evaporation kinetics. Comparison of measured ion currents with predictions from ion evaporation theory yields an anomalously low activation energy (~1.1 eV). This paradox appears to be due to alteration of the pure conj–eet electric field in the scaling laws used for the pure cone–jet regime, due to the substantial ion current density arising even when the ion current is relatively small. Elimination of this interference would require future ion current measurements in the 10–100 pA level. The electrical propulsion characteristics of the emissions from these liquids are determined and found to be excellent, particularly for 10% and 15% (vol) EMI-Im.
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Bravo, Luis, Sameera Wijeyakulasuriya, Eric Pomraning, Peter K. Senecal, and Chol-Bum Kweon. "Large Eddy Simulation of High Reynolds Number Nonreacting and Reacting JP-8 Sprays in a Constant Pressure Flow Vessel With a Detailed Chemistry Approach." Journal of Energy Resources Technology 138, no. 3 (March 24, 2016). http://dx.doi.org/10.1115/1.4032901.
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In military propulsion applications, the characterization of internal combustion engines operating with jet fuel is vital to understand engine performance, combustion phasing, and emissions when JP-8 is fully substituted for diesel fuel. In this work, high-resolution large eddy simulation (LES) simulations have been performed in-order to provide a comprehensive analysis of the detailed mixture formation process in engine sprays for nozzle configurations of interest to the Army. The first phase examines the behavior of a nonreacting evaporating spray, and demonstrates the accuracy in predicting liquid and vapor transient penetration profiles using a multirealization statistical grid-converged approach. The study was conducted using a suite of single-orifice injectors ranging from 40 to 147 μm at a rail pressure of 1000 bar and chamber conditions at 900 K and 60 bar. The next phase models the nonpremixed combustion behavior of reacting sprays and investigates the submodel ability to predict auto-ignition and lift-off length (LOL) dynamics. The model is constructed using a Kelvin Helmholtz–Rayleigh Taylor (KH–RT) spray atomization framework coupled to an LES approach. The liquid physical properties are defined using a JP-8 mixture containing 80% n-decane and 20% trimethylbenzene (TMB), while the gas phase utilizes the Aachen kinetic mechanism (Hummer, et al., 2007, “Experimental and Kinetic Modeling Study of Combustion of JP-8, Its Surrogates, and Reference Components in Laminar Non Premixed Flows,” Proc. Combust. Inst., 31, pp. 393–400 and Honnet, et al., 2009, “A Surrogate Fuel for Kerosene,” Proc. Combust. Inst., 32, pp. 485–492) and a detailed chemistry combustion approach. The results are in good agreement with the spray combustion measurements from the Army Research Laboratory (ARL), constant pressure flow (CPF) facility, and provide a robust computational framework for further JP-8 studies of spray combustion.
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Budiyanto, Muhammad Arif, and Hamnah Ayuningtyas. "PERFORMANCE ANALYSIS OF WATERJET PROPULSION ON UNMANNED SURFACE VEHICLE MODELS." Journal of Applied Engineering Science, May 7, 2021, 1–10. http://dx.doi.org/10.5937/jaes0-29942.
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Waterjet propulsion on an unmanned surface vehicle is a propulsion system with the working principle of taking water from the bottom of the hull into the turbine to be blown back out and converted into the ship's thrust. The resulting thrust depends on the available water forces. The water spray in the nozzle is generated from the inlet at the bottom of the ship which is assisted by a pump on the waterjet. In the inlet section, this will affect the distribution of flow that will pass through the pump and finally out through the nozzle. The purpose of writing this thesis is to analyze the inlet-passage of the waterjet which is variable with the inlet velocity ratio (IVR) to get the maximum efficiency value of the waterjet propulsion system. The work of this thesis uses the computational fluid dynamics (CFD) method and analytical calculations. The inlet velocity ratio is varied from 0.54, 0.59, 0.67, 0.78, 0.94, 1.18, 1.64, and 2.38 which will be compared the results. From the results of the analysis will be obtained the volume that comes out of the waterjet and the results will be obtained the thrust value. The highest thrust value obtained is based on the variation in the IVR value of 2.38, and the maximum efficiency value is 98%.
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Xu, Ruina, Gaoyuan Wang, and Peixue Jiang. "Spray Cooling on Enhanced Surfaces: A Review of the Progress and Mechanisms." Journal of Electronic Packaging 144, no. 1 (August 6, 2021). http://dx.doi.org/10.1115/1.4050046.
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Abstract The rapid development of high-power electronic, energy, and propulsion systems has led us to the point where the performances of these systems are limited by their cooling capacities. Current electronics can generate heat fluxes up to 10–100 W/cm2, and heat flux over 1000 W/cm2 needs to be dissipated with a minimum coolant flow rate in next-generation power electronics. The multiple efficient heat transfer mechanisms have made spray cooling a high heat flux, uniform and efficient cooling technique proven effective in various applications. However, the cooling capacity and efficiency of spray cooling need to be further improved to meet the demands of next-generation ultrahigh-power applications. Engineering of surface properties and structures, which is enabled by state-of-the-art manufacturing techniques, can fundamentally affect the liquid–wall interactions in spray cooling, thus becoming the most promising way to enhance spray cooling. However, the mechanisms of surface-enhanced spray cooling are diverse and ambiguous, causing a lack of clear guiding principles for engineered surface design. Here, the progress in surface engineering-enhanced spray cooling is reviewed for surface structures of millimeter, micrometer, and nanometer scales and hierarchical structured surfaces, and the performances from the reviewed literature are evaluated and compared. The reviewed data show that spray cooling can achieve a critical heat flux (CHF) above 945.7 W/cm2 and a heat transfer coefficient (HTC) up to 57 W/cm2K on structured surfaces without the assistance of secondary gas flow and a CHF and an HTC up to 1250.1 W/cm2 and 250 W/cm2K, respectively, on a smooth surface with the assistance of secondary gas flow. A CHF enhancement up to 110% was achieved on a hybrid micro- and nanostructured surface. A clear map of enhancement mechanisms related to the scales of surface structures is proposed, which can help the design of engineered surfaces in spray cooling. Some future concerns are proposed as well. This work helps the understanding and design of engineered surfaces in spray cooling and provides insights for interdisciplinary applications of heat transfer and advanced engineering materials.
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Kuo, Kenneth K., Grant A. Risha, Brian J. Evans, and Eric Boyer. "Potential Usage of Energetic Nano-sized Powders for Combustion and Rocket Propulsion." MRS Proceedings 800 (2003). http://dx.doi.org/10.1557/proc-800-aa1.1.
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ABSTRACTNano-sized energetic metals and boron particles (with dimensions less than 100 nanometers) possess desirable combustion characteristics such as high heats of combustion and fast energy release rates. Because of their capability to enhance performance, various metals have been introduced in solid propellant formulations, gel propellants, and solid fuels. There are many advantages of incorporating nano-sized materials into fuels and propellants, such as: 1) shortened ignition delay; 2) shortened burn times, resulting in more complete combustion in volume-limited propulsion systems; 3) enhanced heat-transfer rates from higher specific surface area; 4) greater flexibility in designing new energetic fuel/propellants with desirable physical properties; 5) nano-particles can act as a gelling agent to replace inert or low-energy gellants; 6) nano-sized particles can also be dispersed into high-temperature zone for direct oxidation reaction and rapid energy release, and 7) enhanced propulsive performance with increased density impulse. In view of these advantages, numerous techniques have been developed for synthesizing nano-particles of different sizes and shapes. To reduce any possible hazards associated with the handling of nano-sized particles as well as unwanted particle oxidation, various passivation procedures have been developed. Some of these coating materials could enhance the ignition and combustion behavior, others could increase the compatibility of the particles with the surrounding material. Many researchers have been actively engaged in the characterization of the ignition and combustion behavior of nano-sized particles as well as the assessment of performance enhancement of propellants and fuels containing energetic nano-particles. For example, solid fuels could contain a significant percentage of nano-sized particles to increase the mass-burning rate in hybrid rocket motors, the regression rate of solid propellants can be increased by several times when nano-sized particles are incorporated into the formulation. Specifically, hybrid motor data showed that the addition of 13% energetic aluminum powders can increase the linear regression rate of solid HTPB-based fuel by 123% in comparison to the non-aluminized HTPB fuel at a moderate gaseous oxidizer mass flow rate. Strand burner studies of two identical solid propellant formulations (one with 18% regular aluminum powder and the other with 9% aluminum replaced by Alex® powder) showed that nano-sized particles can increase the linear burning rate of solid propellants by 100%. In addition to solid fuels and propellants, spray combustion of bipropellants has been conducted using gel propellants impregnated with nano-sized boron particles as the fuel in a rocket engine. High combustion efficiencies were obtained from burning nano-sized boron particles contained in a non-toxic liquid-fuel spray. Materials characterization such as chemical analyses to determine the active aluminum content, density measurements, and imaging using an electron microscope have been performed on both neat nano-sized particles and mixtures containing the energetic materials. In general, using energetic nano-sized particles as a new design parameter, propulsion performance of future propellants and fuels can be greatly enhanced.
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Chung, J. N., Jun Dong, Hao Wang, S. R. Darr, and J. W. Hartwig. "Cryogenic spray quenching of simulated propellant tank wall using coating and flow pulsing in microgravity." npj Microgravity 8, no. 1 (April 1, 2022). http://dx.doi.org/10.1038/s41526-022-00192-w.
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AbstractIn-space cryogenic propulsion will play a vital role in NASA’s return to the Moon mission and future mission to Mars. The enabling of in-space cryogenic engines and cryogenic fuel depots for these future manned and robotic space exploration missions begins with the technology development of advanced cryogenic thermal-fluid management systems for the propellant transfer lines and storage system. Before single-phase liquid can flow to the engine or spacecraft receiver tank, the connecting transfer line and storage tank must first be chilled down to cryogenic temperatures. The most direct and simplest method to quench the line and the tank is to use the cold propellant itself that results in the requirement of minimizing propellant consumption during chilldown. In view of the needs stated above, a highly efficient thermal-fluid management technology must be developed to consume the minimum amount of cryogen during chilldown of a transfer line and a storage tank. In this paper, we suggest the use of the cryogenic spray for storage tank chilldown. We have successfully demonstrated its feasibility and high efficiency in a simulated space microgravity condition. In order to maximize the storage tank chilldown efficiency for the least amount of cryogen consumption, the technology adopted included cryogenic spray cooling, Teflon thin-film coating of the simulated tank surface, and spray flow pulsing. The completed flight experiments successfully demonstrated that spray cooling is the most efficient cooling method for the tank chilldown in microgravity. In microgravity, Teflon coating alone can improve the efficiency up to 72% and the efficiency can be improved up to 59% by flow pulsing alone. However, Teflon coating together with flow pulsing was found to substantially enhance the chilldown efficiency in microgravity for up to 113%.
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"Properties of Kerosene-Aluminium Nanofluid used to Estimate the Overall Heat Transfer Rates during Regenerative/Film Cooling of Thrust Chambers." International Journal of Engineering and Advanced Technology 9, no. 1S3 (December 31, 2019): 165–69. http://dx.doi.org/10.35940/ijeat.a1033.1291s319.
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Large heat transfer rates are always desired for rocket propulsion applications as high heat loads are associated at the nozzle exit. Different strategies have been employed in order to have high heat transfer coefficients including use of liquid nitrogen, spray cooling etc. ISRO has planned to use aluminium based nano-particles with kerosene in order to cool launching vehicles including GSLV Mk III as it is the heaviest rocket that can carry large payloads. Recently, ISRO has announced to install its own International Space Station (ISS) in future and in such applications larger payloads are to be carried by the rocket. In this work, an analytical study on the thermodynamic properties of the aluminium nano-particles based kerosene nanofluid has been done and an attempt has also been made to develop a temperature and pressure dependent correlation that can be used in computational analysis of thrust chambers while film/regenerative cooling.
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Ghoshal, Anindya, Muthuvel Murugan, Michael J. Walock, Andy Nieto, Blake D. Barnett, Marc S. Pepi, Jeffrey J. Swab, et al. "Molten Particulate Impact on Tailored Thermal Barrier Coatings for Gas Turbine Engine." Journal of Engineering for Gas Turbines and Power 140, no. 2 (October 3, 2017). http://dx.doi.org/10.1115/1.4037599.
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Commercial/military fixed-wing aircraft and rotorcraft engines often have to operate in significantly degraded environments consisting of sand, dust, ash, and other particulates. Marine gas turbine engines are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, calcia–magnesia–alumina–silicate (CMAS) attack, oxidation, and plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. This research represents the complex thermochemomechanical fluid structure interaction problem of semimolten particulate impingement and infiltration onto ceramic thermal barrier coatings (TBCs) into its canonical forms. The objective of this research work is to understand the underpinning interface science of interspersed graded ceramic/metal and ceramic/ceramic composites at the grain structure level for robust coatings and bulk material components for vehicle propulsion systems. This research enhances our understanding of the fundamental relationship between interface properties and the thermomechanical behavior in dissimilar materials for materials by design systems, and creates the ability to develop and fabricate materials with targeted macroscale properties as a function of their interfacial behavior. This project creates a framework to enable the engineered design of solid–solid and liquid–solid interfaces in dissimilar functionalized materials to establish a paradigm shift toward science from the traditional empiricism in engineering TBCs and high temperature highly loaded bulk materials. An integrated approach of modeling and simulation, characterization, fabrication, and validation to solve the fundamental questions of interface mechanisms which affect the properties of novel materials will be validated to guide component material solutions to visionary 2040+ military vehicle propulsion systems.
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Jorgenson, Philip C. E., Joseph P. Veres, Samaun Nili, Shashwath R. Bommireddy, and Kenneth L. Suder. "Analysis of the Honeywell Uncertified Research Engine With Ice Crystal Cloud Ingestion at Simulated Altitudes." Journal of Turbomachinery 142, no. 6 (May 28, 2020). http://dx.doi.org/10.1115/1.4047187.
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Abstract The Honeywell Uncertified Research Engine (HURE), a research version of a turbofan engine that never entered production, was tested in the NASA Propulsion Systems Laboratory (PSL), an altitude test facility at the NASA Glenn Research Center. The PSL is a facility that is equipped with water spray bars capable of producing an ice cloud consisting of ice particles, having a controlled particle diameter and concentration in the airflow. To develop the test matrix of the HURE, the numerical asw analysis of flow and ice particle thermodynamics was performed on the compression system of the turbofan engine to predict operating conditions that could potentially result in a risk of ice accretion due to ice crystal ingestion. The goal of the test matrix was to provide operating conditions such that ice would accrete either in the fan-stator through the inlet guide vane region of the compression system or within the first stator of the high-pressure compressor. The predictive analyses were performed with the mean-line compressor flow modeling code (comdes-melt) which includes an ice particle model. The HURE engine was tested in PSL with the ice cloud over the range of operating conditions of altitude, ambient temperature, simulated flight Mach number, and fan speed with guidance from the analytical predictions. The engine was fitted with video cameras at strategic locations within the engine compression system flow path where ice was predicted to accrete in order to visually confirm ice accretion when it occurred. In addition, traditional compressor instrumentation, such as total pressure and temperature probes, static pressure taps, and metal temperature thermocouples, were installed in targeted areas where the risk of ice accretion was expected. The current research focuses on the analysis of the data that were obtained after testing the HURE engine in PSL with ice crystal ingestion. The computational method (comdes-melt) was enhanced by computing key parameters through the fan-stator at multiple spanwise locations in order to increase the fidelity with the current mean-line method. The Icing Wedge static wet-bulb temperature thresholds were applied for determining the risk of ice accretion in the fan-stator, which is thought to be an adiabatic region. At some operating conditions near the splitter–lip region, other sources of heat (non-adiabatic walls) were suspected to be the cause of accretion, and the Icing Wedge was not applied to predict accretion at that location. A simple order-of-magnitude heat transfer model was implemented into the comdes-melt code to estimate the wall temperature minimum and maximum thresholds that support ice accretion, as observed by video confirmation. The results from this model spanned the range of wall temperatures measured on a previous engine that experienced ice accretion at certain operating conditions. The goal of this study is to show that the computational process developed on earlier engine icing tests can be used to provide an icing risk assessment in adiabatic regions for other engines.