Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis

[EN] In-cylinder pressure analysis is a key tool for engine research and diagnosis and it has been object of study from the beginning of the internal combustion engines. One of its most useful application is combustion analysis on the basis of the First Law of Thermodynamics. However, heat release law calculations use the in-cylinder pressure derivative signal. Hence, the noise is increased and pressure filtering becomes necessary to remove high frequency noise, thus allowing for accurate combustion analyses. In this work, a methodology to set the cut-off frequency of a low-pass filter is proposed. Statistical criteria are used to separate the signal from the noise through the calculation of the Discrete Fourier Transform of several consecutive in-cylinder pressures cycles. Thus, only physically meaningful information is preserved. The proposed methodology is compared with some adaptive and non-adaptive algorithms used to select the cut-off frequencies, and it shows a good ability to adapt to different engine operating conditions. © 2011 Elsevier Ltd. All rights reserved.The authors thank the Universidad Politécnica de Valencia (PAID-06-09) and Generalitat Valenciana (GV/2010/045) for its valuable support to this work.Payri González, F.; Olmeda González, PC.; Guardiola García, C.; Martín Díaz, J. (2011). Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis. Applied Thermal Engineering. 31:2869-2876. https://doi.org/10.1016/j.applthermaleng.2011.05.012S286928763

Molecular systematics, historical ecology, and phylogeography of <i>Halimeda</i> (Bryopsidales)

Halimeda (Bryopsidales), a genus of calcified, segmented green seaweeds, abounds in reefs and lagoons throughout the tropics. To investigate phylogenetic, phylogeographic, and historic ecological relationships of the genus, the nuclear rDNA including the SSU and both ITS regions were sequenced. A maximum likelihood tree revealed the following: (1) there were anatomical and morphological synapomorphies for five well-supported lineages; (2) the last common ancestor of one lineage invaded sandy substrata; those of two other lineages established in wave-affected habitats, whereas the cenancestor of the remaining two lineages occupied sheltered rocky slopes. Yet, several species adapted to new habitats subsequently, resulting in several cases of convergence; (3) all lineages separated into Atlantic and Indo-Pacific daughters, likely resulting from the rise of the Panamanian Isthmus. Each daughter pair gave rise to additional convergent species in similar habitats in different oceans; (4) Halimeda opuntia, the only monophyletic pantropical species detected so far, dispersed from the Indo-Pacific into the Atlantic well after the closure event; (5) minor SSU-sequence differences across species and phylogeographic patterns of vicariance indicated a relatively recent diversification of the extant diversity. Cretaceous and Early Tertiary fossil look-alikes of modern species must then have resulted from iterative convergence

A computational methodology to account for the liquid film thickness evolution in Direct Numerical Simulation of prefilming airblast atomization

Prefilming airblast atomization is widely used in aero engines. Fundamental studies on the annular configuration of airblast atomizers are difficult to realize. For this reason, researchers focused on planar configurations. In this regard, the Karlsruhe Institute of Technology (KIT) developed a test rig to conduct experimental activities, conforming a large database with results for different conditions. Such data allow validation of two-phase flow calculations concerning primary atomization on these devices. The present investigation proposes a Direct Numerical Simulation (DNS) on the KIT planar configuration through the Volume of Fluid (VOF) method within the PARIS code. The novelty compared to DNS reported in the literature resides in the use of a boundary condition that accounts not only for the gas inflow turbulence but also for the spatio-temporal evolution of the liquid film thickness at the DNS inlet and its effect on turbulence. The proposed methodology requires computing precursor single-phase and two-phase flow Large-Eddy Simulations. Results are compared to DNS that only account for a constant (both timewise and spanwise) liquid film thickness at the domain inlet, validating the workflow. The proposed methodology improves the qualitative description of the breakup mechanism, as its different stages (liquid accumulation behind the prefilmer edge, bag formation, bag breakup, ligament formation and ligament breakup) coexist spanwise for a given temporal snapshot. This implies more continuous atomization than the one predicted by the constant film thickness case, which showed the same breakup stage to be present along the prefilmer span for a given instant and led to a more discretized set of atomization events. The proposed workflow allows quantifying the influence of the liquid film flow evolution above the prefilmer on primary breakup frequency and atomization features.Comment: Preprint submitted to International Journal of Multiphase Flo

A spectroscopy study of gasoline partially premixed compression ignition spark assisted combustion

Nowadays many research efforts are focused on the study and development of new combustion modes, mainly based on the use of locally lean air–fuel mixtures. This characteristic, combined with exhaust gas recirculation, provides low combustion temperatures that reduces pollutant formation and increases efficiency. However these combustion concepts have some drawbacks, related to combustion phasing control, which must be overcome. In this way, the use of a spark plug has shown to be a good solution to improve phasing control in combination with lean low temperature combustion. Its performance is well reported on bibliography, however phenomena involving the combustion process are not completely described. The aim of the present work is to develop a detailed description of the spark assisted compression ignition mode by means of application of UV–Visible spectrometry, in order to improve insight on the combustion process. Tests have been performed in an optical engine by means of broadband radiation imaging and emission spectrometry. The engine hardware is typical of a compression ignition passenger car application. Gasoline was used as the fuel due to its low reactivity. Combining broadband luminosity images with pressure-derived heat-release rate and UV–Visible spectra, it was possible to identify different stages of the combustion reaction. After the spark discharge, a first flame kernel appears and starts growing as a premixed flame front, characterized by a low and constant heat-release rate in combination with the presence of remarkable OH radical radiation. Heat release increases temperature and pressure inside the combustion chamber, which causes the auto-ignition of the rest of the unburned mixture. This second stage is characterized by a more pronounced rate of heat release and a faster propagation of the reactions through the combustion chamber. Moreover, the measured UV–Visible spectra show some differences in comparison with the other stages. The relative intensities in of spectra from different combustion radicals have also been related to the different combustion phases.The authors acknowledge that part of this work was performed in the frame of Project DUFUEL TRA2011-26359, funded by the Spanish Government. The authors also thank GM for technical assistance and its support in other parts of this work.Pastor Soriano, JV.; García Oliver, JM.; García Martínez, A.; Micó Reche, C.; Durret, R. (2013). A spectroscopy study of gasoline partially premixed compression ignition spark assisted combustion. Applied Energy. 104:568-575. https://doi.org/10.1016/j.apenergy.2012.11.030S56857510

ECU-oriented models for NOx prediction. Part 2: adaptive estimation by using an NOx sensor

The implantation of nitrogen oxide sensors in diesel engines is necessary in order to track emissions at the engine exhaust line for diagnosis and control of the after-treatment devices. However, the use of models is still necessary since the sensor outputs are delayed and filtered. The present paper deals with the problem of the nitrogen oxide estimation in two parts; Part 1 deals with a control-oriented model for the nitrogen oxide estimation, while Part 2 presents data fusion of the model and the sensor to improve the estimation, which is presented in the following. The use of models for the nitrogen oxide estimation is an alternative but the drift and the ageing are still issues. In order to overcome this problem, the fusion of different signals can be carried out in a smart way by means of a Kalman filter. There exist different ways of presenting this fusion, from directly tracking the bias to updating the model parameters. For this, different algorithms are proposed in this paper with the aim of correcting the model output. Furthermore, the estimation of the actual nitrogen oxide concentration, by preventing sensor delay and filtering, is also integrated in the algorithm, which is a suitable strategy for combining nitrogen oxide sensors and models on an onboard basis.Guardiola, C.; Climent, H.; Pla Moreno, B.; Blanco-Rodriguez, D. (2015). ECU-oriented models for NOx prediction. Part 2: adaptive estimation by using an NOx sensor. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 229(10):1345-1360. doi:10.1177/0954407014561278S134513602291

Evaluation of natural and tracer fluorescent emission methods for droplet size measurements in a diesel spray

The final publication is available at Springer via http://dx.doi.org/10.1007/s12239-012-0070-zSpray sizing that records fluorescent emission and scattered light has been widely applied to spray diagnostics over the last two decades. Different experimental strategies have been developed, but comparing the different solutions offered has remained of interest to experimentalists. In this work, a comparison of two fluorescence strategies for measuring droplet size in the liquid phase of a last-generation DI diesel spray is conducted. The natural fluorescent emission of a commercial diesel fuel and the fluorescence emitted by a tracer (Rhodamine B) are compared using theoretical and experimental approaches. The LIF/Mie ratio commonly called Planar Droplet Sizing (PDS) technique is applied in two different ways to elucidate the possible advantages of using a fluorescent dopant. The sprays were injected under non-evaporative conditions into a constant pressure vessel that simulates densities present at the moment of injection in currently used passenger car diesel engines. Characterization of the signal properties was performed by measuring the absorption coefficient, fluorescence emission spectrum, quantum yield and lifetime of both configurations. The scattered light and fluorescence intensities were calculated to verify the dependencies of the droplet surface and volume. When applying the two techniques to quantify droplet size in dense diesel sprays, the results show that signal weakness and lack of control over the properties of natural fluorescence produce distortion in the shape of the spray and cause measurements to be unreliable. © 2012 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.This research has been funded in the frame of the project PROFUEL reference TRA2011-26293 from Ministerio de Ciencia e Innovacion. The injectors are part of the ECN international project.Pastor Soriano, JV.; Payri, R.; Salavert Fernandez, J.; Manin, J. (2012). Evaluation of natural and tracer fluorescent emission methods for droplet size measurements in a diesel spray. International Journal of Automotive Technology. 13(5):713-724. https://doi.org/10.1007/s12239-012-0070-zS713724135Albrecht, H. E., Damaschke, N., Borys, M. and Tropea, C. (2003). Laser Doppler and Phase Doppler Measurement Techniques. Springer. Berlin.Barnes, M. D., Whitten, W. B. and Ramsey, J. M. (1994). Enhanced fluorescence yields through cavity quantumelectrodynamic effects in microdroplets. J. Optical Society of America B 11,7, 1297–1304.Benajes, J., Molina, S., Novella, R., Amorim, R., Ben Hadj Hamouda, H. and Hardy, J. (2010). Comparison of two injection systems in an HSDI diesel engine using split injection and different injector nozzles. Int. J. Automotive Technology 11,2, 139–146.Charalampous, G. and Hardalupas, Y. (2011). Method to reduce errors of droplet sizing based on the ratio of fluorescent and scattered light intensities (laser-induced fluorescence/Mie technique). Applied Optics, 50, 3622–3637.Chen, G., Mazumder, M., Chang, R. K., Swindal, J. C. and Acker, W. P. (1996). Laser diagnostics for droplet characterization: Application of morphology dependent resonances. Progress in Energy and Combustion Science 22,2, 163–188.Desantes, J. M., Payri, R., Garcia, J. M. and Salvador, F. J. (2007). A contribution to the understanding of isothermal diesel spray dynamics. Fuel 86,7–8, 1093–1101.Domann, R. and Hardalupas, Y. A. (2000). Study of parameters that influence the accuracy of the planar droplet sizing (PDS) technique. Part. Part. Syst. Charact. 3–11.Domann, R. and Hardalupas, Y. A. (2001). Spatial distribution of fluorescence within large doplets and its dependence on dye concentration. Applied Optics 40,21, 3586–3597.Domann, R. and Hardalupas, Y. A. (2002). Quantitative measurement of planar droplet sauter mean diameter in sprays using planar droplet sizing. 11th Int. Symp. Application of Laser Techniques to Fluid Mechanics, Lisbon, Portugal.Eckbreth, A. C. (1988). Laser Diagnostics for Combustion Species and Temperature. Abacus. Cambridge. Mass.Greenhalgh, D. A. (1999). Planar measurements of fuel vapour, liquid fuel, liquid droplet size and soot. Planar Optical Measurement Methods for Gas Turbine Components, 1–7.Im, K., Lin, K., Lai, M. and Chon, M. (2011). Breakup modeling of a liquid jet in cross flow. Int. J. Automotive Technology 12,4, 489–496.Jermy, M. C. and Greenhalgh, D. A. (2000). Planar dropsizing by elastic and fluorescence scattering in sprays too dense for phase doppler measurement. Appl. Phys. B, 71, 703–710.Kim, Y., Kim, K. and Lee, K. (2011). Effect of a 2-stage injection strategy on the combustion and flame characteristics in a PCCI engine. Int. J. Automotive Technology 12,5, 639–644.Ko, F. H., Weng, L. Y., Ko, C. J. and Chu, T. C. (2006). Characterization of imprinting polymeric temperature variation with fluorescent Rhodamine B molecule. Microelectronic Engineering, 83, 864–868.Lakowicz, J. R. (2006). Principles of Fluorescence Spectroscopy. 3rd Edn. Springer.Lee, S. H., Teong, J., Lee, J. T., Ryou, H. S. and Hong, K. (2005). Investigation on spray characteristics under ultrahigh injection pressure conditions. Int. J. Automotive Technology 6,2, 125–131.Lee, B., Song, J., Chang, Y. and Jeon, C. (2010). Effect of the number of fuel injector holes on characteristics of combustion and emissions in a diesel engine. Int. J. Automotive Technology 11,6, 783–791.LeGal, P., Farrugia, N. and Greenhalgh, D. A. (1999). Laser sheet dropsizing of dense sprays. Optics and Laser Techn., 31, 75–83.Lockett, R. D., Richter, J. and Greenhalgh, D. A. (1998). The characterisation of a diesel spray using combined laser induced fluorescence and laser sheet dropsizing. Conf. Lasers and Electro-Optics Europe.Magde, D., Rojas, G. E. and Seybold, P. (1999). Solvent dependence of the fluorescence lifetimes of xanthene dyes. Photochem. Photobiol., 70, 737.Naber, J. and Siebers, D. (1996). Effects of gas density and vaporization on penetration and dispersion of diesel sprays. SAE Paper No. 960034.Pastor, J. V., López, J. J., Juliá, J. E. and Benajes, J. V. (2002). Planar laser-induced fluorescence fuel concentration measurements in isothermal diesel sprays. Opt. Express 10,7, 309–323.Pastor, J. V., Payri, R., Araneo, L. and Manin, J. (2009). Correction method for droplet sizing by laser-induced fluorescence in a controlled test situation. Optical Engineering 48,1, 013601.Payri, R., Garcia, J. M., Salvador, F. J. and Gimeno, J. (2005a). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84, 551–561.Payri, R., Salvador, F. J., Gimeno, J. and Soare, V. (2005b). Determination of diesel sprays characteristics in real engine in-cylinder air density and pressure conditions. J. Mech. Sci. Technol., 19, 2040–2052.Payri, R., Tormos, B., Salvador, F. J. and Araneo, L. (2008). Spray droplet velocity characterization for convergent nozzles with three different diameters. Fuel 87,15, 3176–3182.Payri, F., Pastor, J., Payri, R. and Manin, J. (2011). Determination of the optical depth of a DI diesel spray. J. Mech. Sci. Technol., 25, 209–219.Potz, D., Chirst, W. and Dittus, B. (2000). Diesel nozzle: The determining interface between injection system and combustion chamber. Conf. Thermo and Fluid-dynamic Processes in Diesel Engines, Valencia, Spain.Ramírez, A. I., Som, S., Aggarwal, S. K., Kastengren, A. L., El-Hannouny, E. M., Longman, D. E. and Powell, C. F. (2009). Quantitative X-ray measurements of highpressure fuel sprays from a production heavy duty diesel injector. Experiments in Fluids 47,1, 119–134.Schulz, C. and Sick, V. (2005). Tracer-LIF diagnostics: quantitative measurement of fuel concentration, temperature and fuel/air ratio in practical combustion systems. Progress in Energy and Combustion Science, 31, 75–121.Sjoback, R. and Nygren, J. and Kubista, M. (1998). Characterization of fluorescein—oligonucleotide conjugates and measurement of local electrostatic potential. Biopolymers, 46, 445–453.Soare, V. (2007). Phase Doppler Measurement in Diesel Dense Sprays: Optimisation of Measurements and Study of the Orifice Geometry Influence Over the Spray at Microscopic Level. Ph.D. Dissertion. E.T.S. Ingenieros Industriales. Universidad Politécnica de Valencia. Spain.Williams, A. T. R., Winfield, S. A. and Miller, J. N. (1983). Relative fluorescence quantum yields using a computer controlled luminescence spectrometer. Analyst., 108, 1067.Yeh, C. N., Kosaka, H. and Kamimoto, T. A. (1993). Fluorescence/scattering imaging technique for instantaneous 2-D measurements of particle size distribution in a transient spray. Proc. 3rd Cong. Opt. Part. Sizing, Yokohama, Japan, 335–361

Application of UV Visible Light Absorption and Scattering technique to low absorption fuels under diesel-like conditions

Light Absorption and Scattering technique (LAS) has been applied for the measurement of fuel vapour distribution in diesel-type sprays. This technique is usually limited to fuels with relatively high absorptivity, which are sometimes not commonly used as surrogate fuels. In the present paper, a comparison of fuels with very different absorptive properties has been made to determine the range of application of the methodology. A calibration procedure has been applied to n-decane (DEC), a binary blend of n-decane and n-hexadecane (50DEC) and three blends of n-heptane with a highly-absorpting fuel (HEPB1, HEPB2 and HEPB3). This methodology enables the in-situ quantification of absorption coefficients at high pressure and temperature by creating a uniform mixture inside the cylinder. Results have been later applied for the quantification of fuel vapour distribution in sprays for DEC, 50DEC and HEPB3. Results obtained with these range of fuels have enabled to establish the limit in terms of absorption coefficient needed to get consistent results with the technique.This work was partially funded by the Government of Spain through Project TRA2011-26359 and Grant BES-2012-059721. In addition, the authors acknowledge that some equipment used in this work has been partially supported by FEDER project funds (FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain.Pastor Soriano, JV.; García Oliver, JM.; López, JJ.; Micó Reche, C. (2016). Application of UV Visible Light Absorption and Scattering technique to low absorption fuels under diesel-like conditions. Fuel. 179:258-266. https://doi.org/10.1016/j.fuel.2016.03.080S25826617

Evolutionary history of the Corallinales (Corallinophycidae, Rhodophyta) inferred from nuclear, plastidial and mitochondrial genomes

Systematics of the red algal order Corallinales has a long and convoluted history. In the present study, molecular approaches were used to assess the phylogenetic relationships based on the analyses of two datasets: a large dataset of SSU sequences including mainly sequences from GenBank; and a combined dataset including four molecular markers (two nuclear: SSU, LSU; one plastidial: psbA; and one mito- chondrial: COI). Phylogenetic analyses of both datasets re-affirmed the monophyly of the Corallinales as well as the two families (Corallinaceae and Hapalidiaceae) currently recognized within the order. Three of the four subfamilies of the Corallinaceae (Corallinoideae, Lithophylloideae, Metagoniolithoideae) were also resolved as a monophyletic lineage whereas members of the Mastophoroideae were resolved as four distinct lineages. We therefore propose to restrict the Mastophoroideae to the genera Mastophora, Metamastophora, and possibly Lithoporella in the aim of rendering this subfamily monophyletic. In addition, our phylogenies resolved the genus Hydrolithon in two unrelated lineages, one containing the gener- itype Hydrolithon reinboldii and the second containing Hydrolithon onkodes, which used to be the generitype of the now defunct genus Porolithon. We therefore propose to resurrect the genus Porolithon for the second lineage encompassing those species with primarily monomerous thalli, and trichocyte arrangements in large pustulate horizontal rows. Moreover, our phylogenetic analyses revealed the presence of cryptic diversity in several taxa, shedding light on the need for further studies to better circumscribe species frontiers within the diverse order Corallinales, especially in the genera Mesophyllum and Neogoniolithon.Web of Scienc

Comparison of different techniques for characterizing the diesel injector internal dimensions

[EN] The geometry of certain parts of diesel injectors is key to the injection, atomization and fuel-air mixing phenomena. Small variations on the geometrical parameters may have a strong influence on the aforementioned processes. Thus, OEMs need to assess their manufacturing tolerances, whereas researchers in the field (both experimentalists and modelers) rely on the accuracy of a certain metrology technique for their studies. In the current paper, an investigation of the capability of different experimental techniques to determine the geometry of a modern diesel fuel injector has been performed. For this purpose, three main elements of the injector have been evaluated: the control volume inlet and outlet orifices, together with the nozzle orifices. While the direct observation of the samples through an optical microscope is only possible for the simplest pieces, both Computed Tomography Scanning and the visualization of silicone molds technique have proven their ability to characterize the most complex internal shapes corresponding to the internal injector elements. Indeed, results indicate that the differences observed among these methodologies for the determination of the control volume inlet orifice diameter and the nozzle orifice dimensions are smaller than the uncertainties related to the experimental techniques, showing that they are both equally accurate. This implies that the choice of a given technique for the particular application of determining the geometry of diesel injectors can be done on the basis of availability, intrusion and costs, rather than on its accuracy.This work was partly sponsored by "Ministerio de Economia y Competitividad", of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor", Reference TRA2015-67679-c2-1-R.Salvador, FJ.; Gimeno, J.; De La Morena, J.; Carreres, M. (2018). Comparison of different techniques for characterizing the diesel injector internal dimensions. Experimental Techniques. 42(5):467-472. https://doi.org/10.1007/s40799-018-0246-1S467472425Mobasheri R, Peng Z, Mostafa S (2012) Analysis the effect of advanced injection strategies on engine performance and pollutant emissions in a heavy duty DI-diesel engine by CFD modeling. Int J Heat Fluid Flow 33(1):59–69Dhar A, Agarwal AK (2015) Experimental investigations of the effect of pilot injection on performance, emissions and combustion characteristics of Karanja biodiesel fuelled CRDI engine. Energy Convers Manag 93:357–366Mohan B, Yang W, Chou SK (2013) Fuel injection strategies for performance improvement and emissions reduction in compression ignition engines—a review. Renew Sust Energ Rev 28(x):664–676Petrovic V, Bracanovic Z, Grozdanic B, Petrovic S, Sazhin S, Knezevic D (2015) The design of a full flow dilution tunnel with a critical flow venturi for the measurement of diesel engine particulate emission. FME Trans 43(2):99–106Ilić Z, Rasuo B, Jovanović M, Janković D (2013) Impact of changing quality of air/fuel mixture during flight of a piston engine aircraft with respect to vibration low frequency spectrum. FME Trans 41(1):25–32Luján JM, Tormos B, Salvador FJ, Galgar K (2009) Comparative analysis of a DI diesel engine fuelled with biodiesel blends during the European MVEG-A cycle: Preliminaru study I. Biomass & Bioenergy 33(6–7):941–947Postrioti L, Mariani F, Battistoni M (2012) Experimental and numerical momentum flux evaluation of high pressure diesel spray. Fuel 98:149–163Payri R, Salvador FJ, Gimeno J, Venegas O (2016) A technique to match the refractive index of different diesel fuels with the refractive index of transparent materials to improve the experimental visualization. Exp Tech 40(1):261–269Duran SP, Porter JM, Parker TE (2015) Ballistic imaging of diesel sprays using a picosecond laser: characterization and demonstration. Appl Opt 54(7):1743Payri R, Salvador FJ, Gimeno J et al (2011) Flow regime effects on non-cavitating injection nozzles over spray behavior. Int J Heat Fluid Flow 32(1):273–284Koukouvinis P, Gavaises M, Li J, Wang L (2016) Large Eddy simulation of diesel injector including cavitation effects and correlation to erosion damage. Fuel 175:26–39Som S, Aggarwal SK (2010) Effects of primary breakup modeling on spray and combustion characteristics of compression ignition engines. Combust Flame 157(6):1179–1193Salvador FJ, De la Morena J, Martínez-López J, Jaramillo D (2017) Assessment of compressibility effects on internal nozzle flow in diesel injectors at very high injection pressures. Energy Convers Manag 132:221–230Salvador FJ, Gimeno J, de la Morena J, Martí-Aldaraví P (2012) Using one-dimensional modelling to analyze the influence of the use of biodiesels on the dynamic behaviour of solenoid-operated injectors in common rail systems: Results of the simulation and discussion. Energy Convers Manag 54(1):122–132Taghavifar H, Khalilarya S, Jafarmadar S, Baghery F (2016) 3-D numerical consideration of nozzle structure on combustion and emission characteristics of DI diesel injector. Appl Math Model 40(19–20):8630–8646Edelbauer W (2017) Numerical simulation of cavitating injector flow and liquid spray break-up by combination of Eulerian–Eulerian and volume-of-fluid methods. Comput Fluids 144:19–33Salvador FJ, Carreres M, Jaramillo D, Martínez-López J (2015) Comparison of microsac and VCO diesel injector nozzles in terms of internal nozzle flow characteristics. Energy Convers Manag 103:284–299Salvador FJ, Martínez-López J, Romero JV, Roselló MD (2013) Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations. Int J Comput Math 91, no. June:24–31Payri R, Salvador FJ, Carreres M, De la Morena J (Apr. 2016) Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis. Energy Convers Manag 114:376–391Salvador FJ, Hoyas S, Novella R, Martinez-López J (2011) Numerical simulation and extended validation of two-phase compressible flow in diesel injector nozzles. Proc Inst Mech Eng Part-D-J Automob Eng 225(D4):545–563Satkoski C, Shaver G (2011) Piezoelectric fuel injection: pulse-to-pulse coupling and flow rate estimation. IEEE/ASME Trans Mechatron 16(4):627–642Ferrari A, Mittica A (2016) Response of different injector typologies to dwell time variations and a hydraulic analysis of closely-coupled and continuous rate shaping injection schedules. Appl Energy 169:899–911Payri R, Salvador FJ, Gimeno J, De la Morena J (2011) Analysis of diesel spray atomization by means of a near-nozzle field visualization technique. At Sprays 21(9):753–774Li T, Moon S, Sato K, Yokohata H (Feb. 2017) A comprehensive study on the factors affecting near-nozzle spray dynamics of multi-hole GDI injectors. Fuel 190:292–302Yu W, Yang W, Zhao F (2017) Investigation of internal nozzle flow, spray and combustion characteristics fueled with diesel, gasoline and wide distillation fuel (WDF) based on a piezoelectric injector and a direct injection compression ignition engine. Appl Therm Eng 114:905–920Salvador FJ, Carreres M, Crialesi-Esposito M, Plazas AH (2017) Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance. Proc Inst Mech Eng Part D J Automob EngMacian V, Bermúdez V, Payri R, Gimeno J (2003) New technique for determination of internal geometry of a diesel nozzle with the use of silicone methodology. Exp Tech 27, no April:39–43Piano A, Millo F, Postrioti L, Biscontini G, Cavicchi A, and Pesce FC, (2016) “Numerical and experimental assessment of a solenoid common-rail injector operation with advanced injection strategies,” SAE Int J Engines 9(1)Mitroglou N, Lorenzi M, Santini M, Gavaises M (2016) Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows. Exp Fluids 57(11):1–14Kastengren AL, Tilocco FZ, Powell CF, Manin J, Pickett LM, Payri R, Bazyn T (2012) Engine combustion network (ECN): measurements of nozzle geometry and hydraulic behavior. At Sprays 22(12):1011–1052Otsu N (1979) A threshold selection method from gray-level histograms. IEEE Trans Syst Man Cybern 9(1):62–6

Allelopathic interactions between the brown algal genus Lobophora (Dictyotales, Phaeophyceae) and scleractinian corals

Allelopathy has been recently suggested as a mechanism by which macroalgae may outcompete corals in damaged reefs. Members of the brown algal genus Lobophora are commonly observed in close contact with scleractinian corals and have been considered responsible for negative effects of macroalgae to scleractinian corals. Recent field assays have suggested the potential role of chemical mediators in this interaction. We performed in situ bioassays testing the allelopathy of crude extracts and isolated compounds of several Lobophora species, naturally associated or not with corals, against four corals in New Caledonia. Our results showed that, regardless of their natural association with corals, organic extracts from species of the genus Lobophora are intrinsically capable of bleaching some coral species upon direct contact. Additionally, three new C-21 polyunsaturated alcohols named lobophorenols A-C (1-3) were isolated and identified. Significant all elopathic effects against Acropora muricata were identified for these compounds. In situ observations in New Caledonia, however, indicated that while allelopathic interactions are likely to occur at the macroalgal-coral interface, Lobophora spp. rarely bleached their coral hosts. These findings are important toward our understanding of the importance of allelopathy versus other processes such as herbivory in the interaction between macroalgae and corals in reef ecosystems