Bragin, Maxim

Molkov, Vladimir

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Institutions of the Russian Academy of SciencesJoint Institute for High Temperatures RASInstitute of Problems of Chemical Physics RASKabardino-Balkarian State UniversityPhysics of Extreme Statesof Matter — 2010Chernogolovka, 2010Physics of Extreme States of Matter — 2010Edited by academician Fortov V. E., Karamurzov B. S., Temrokov A. I., Efremov V.P.,Khishchenko K.V., Sultanov V.G., Levashov P.R., Kanel G. I., Iosilevski I. L., Milyavskiy V.V.,Mintsev V.B., Petrov O. F., Savintsev A.P., Shpatakovskaya G.V.This compendium is devoted to investigations in the fields of thermal physics of extreme states of matter andphysics of high energy densities. Different models and results of theoretical calculations of equations of stateof matter at high pressure and temperature, physics of shock and detonation waves, experimental methods ofdiagnostics of ultrafast processes, interaction of intense laser, x-ray and microwave radiation, powerful ion andelectron beams with matter, techniques of intense energy fluxes generation, low-temperature plasma physics,issues of physics and power engineering, and technology projects are considered. The majority of the works hasbeen presented at the XXV International Conference on Equations of State for Matter (March 1–6, 2010, Elbrus,Kabardino-Balkaria, Russia). The edition is intended for specialists in physical and technical problems of powerengineering.The conference is sponsored by the Russian Academy of Sciences and the Russian Foundation for Basic Research(grant No. 10-02-06043).ISBN 978-5-901675-96-0c© Institute of Problems of Chemical Physics, Russian Academy of Sciences,Chernogolovka, 2010M.F., Laskin I.N., Saveliev A.S., Semin N.V., VolodinV.V. // J. Lost Prevent. Process Industr. 2008.V. 21(2). P. 185–198.4. Gelfand B.E., Popov O.E., Chayvanov B.B. // Hydro-gen: parameters of combustion and explosion (in Rus-sian). M.: 2008. P. 288.5. Sakurai A. // Proc. 15th Shock Waves and Shock TubesSymposium 1985. P. 77–86.6. Matthews C. // A quick guide to pressure relief valves(PRVs). Professional Engineering Publishing. London.2004.7. Divakov O.G., Eremin A.V., Ziborov V.S. // CD-Proc.22nd Int. Symp. Shock Waves. 1999. Paper # 3974.8. Bozhenkov S.A., Starikovskaia S.M., Starikovskii A.Yu.// 17th Int. Symposium on Gas Kinetics. 2002. CP. 25.THE EFFECT OF BURST DISK OPENING ON COMBUSTIBLE MIXTURE FORMATIONPRECEEDING HYDROGEN SPONTANEOUS IGNITIONBragin M.V.∗, Molkov V.V.University of Ulster, Newtownabbey, United Kingdom (Great Britain)*mv.bragin@ulster.ac.ukAbstract. Up to date little research has been doneto study the effect of a finite time burst disk ruptureon the formation of combustible mixture and sponta-neous ignition of hydrogen during sudden release intoair. An experimental observation of spontaneous hy-drogen ignition at storage pressures as low as 13.5 barwas reported recently [1]. The paper investigates thedifference in dynamics of the initial stage after openingof an imaginary non-inertial membrane and realisticinertial burst disk separating high pressure hydrogenfrom the air within a pressure relief device (PRD). Thenumerical simulations performed by the LES model.Introduction. Hydrogen is an ecologically cleanfuel to be used as an energy carrier or storage for re-newable sources. Safety is the main concern for theemerging hydrogen economy.It is known that sudden release of high-pressure hy-drogen into air can spontaneously ignite without anyapparent ignition sources present [2]. However, no ref-erences to spontaneous ignition problem or engineeringdesign to avoid it can be found in regulations, codesand standards for handling compressed hydrogen.Earlier numerical studies by Bazhenova et al. [3, 4],Liu et al. [5], and Xu et al. [6] were focused onunconfined release from high-pressure storage directlyinto the atmosphere. While spontaneous ignition wasdemonstrated by numerical simulations, no experimen-tal proof exists up to date. Experimentally sponta-neous ignition was observed in experiments with at-tachment tubes positioned downstream of a membraneby Dryer et al. [7], Mogi et al. [8, 9], Golub et al.[10, 11], and Pinto et al. [12]. The most recent studyby Lenkevich et al. [1] demonstrated spontaneous ig-nition in a T–shaped pressure relief device (PRD) forinitial hydrogen pressure as low as 13.5 atm.In their earlier work Dryer et al. [7] speculated onthe importance of the initial stage of membrane rup-ture on the mixing and subsequent spontaneous igni-tion process. They concluded that at low pressures,the chemical ignition time becomes the limiting fac-tor, while at high pressures, the mixing time to achievesignificant flammable mixture volume is the limitingfactor. Up to now a little research have been done onthis subject except recent works by Wen et al. [13] andLee and Jeung [14] where the problem was partially ad-dressed. The aim of this work is a comparative studyof the initial dynamics of hydrogen-air mixing in thegeometry of the pressure relief device (PRD) [1] for twocases: non-inertial membrane and inertial burst disk.The model. The LES model of spontaneous igni-tion described in [15] is applied in this study. The setof main governing equations can be found elsewhere[16]. The RNG theory is employed for subgrid-scalemodelling of turbulence. The reaction rate that ap-pears in species transport equation was modelled us-ing the Eddy-Dissipation-Concept (EDC) model [17],which incorporates detailed Arrhenius chemical kinet-ics. The model assumes that reaction occurs in smallturbulent structures, called fine scales. In this studythe detailed 21–step chemical reaction mechanism ofhydrogen combustion in air employing 37 elementaryreactions is applied [18].Numerical details and burst disk rupturemodelling approach. The geometry of high pres-sure system and T-shape PRD was taken from [1]. Thehigh pressure system consisted of a 210 mm long tubewith 16 mm internal diameter (ID) followed by a 280mm long tube with 10 mm ID at the end of which theburst disk followed by a PRD was installed. PRD had6.5 mm ID main tube with a flat end having two sideopenings connected to exit tubes of 4 mm ID.The grid was created using GAMBIT tool of com-mercial CFD package FLUENT. The main tube andexit tubes were meshed with an unstructured hexa-hedral grid with uniform control volume (CV) size ofabout 400 µm both along the tube and a similar char-acteristic CV size in the cross-section. The anticipatedcombustion area was meshed with tetrahedral CVswith size of about 200 µm. The high-pressure chamberwas meshed with the smallest CV size of about 250 µmclustered near the entrance to the simulated tube/low-pressure chamber and rapidly increasing away from itreaching the maximum cell width of 10 mm at the farend. The total number of control volumes was equalto 417.685.Following [19], the rupture time of the diaphragmwas calculated using equation (1), where ρ is the den-sity of the diaphragm material (8900 kg/m3 for an-nealed copper), b and d are the thickness (50 µm) andthe diameter of the diaphragm (6.5 mm), respectively,113Physics of Extreme States of Matter—2010 / Eds. Fortov V. E. et al. Chernogolovka: IPCP RAS, 2010. P. 113–115c© Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 2010Figure 1. Comparison of temperature and mole hydrogen concentration dynamics for instant opening (left) and membranerupture (right).the value of k is 0.92, pressure p is taken as 13.5 atm.t = k(ρbdp) 12= 0.92×(8900 5 10−5 6.5 10−31.37 106) 12= 42.3 µs. (1)The burst-disk rupture process was approximated by10 concentric rings openings in a step-like manner withopening times of each section listed in Table 1.Table 1. Opening time of sections for 13.5 bar release.Section 1 2 3 4 5 6 7 8 9 10Time, µs 0 4.7 9.4 14.1 18.8 23.5 28.2 32.9 37.6 42.3Non-slip impermeable adiabatic boundary condi-tions were used on all walls. The high pressure systemwas modelled as closed to exclude potential effects ofnumerical boundary conditions on the process. Thisassumption is applicable because the observation timein simulation is less than a time required for rarefac-tion wave to reach the end of high-pressure system.Initial conditions for high-pressure system were p0 =13.5 atm, T0 = 300 K and the mole fraction of hydro-gen equal to 1. Low pressure chamber was filled withair (0.23 mass fraction of oxygen and 0.77 of nitrogen)at p0 = 1 atm and T0 = 300 K.The problem was simulated using general-purposeCFD package FLUENT 6.3.26, which realises control-volume based finite-difference method. The solver usedexplicit linearisation of the governing equations withexplicit method for solution of linear equation set. Asecond order upwind scheme with AUSM flux split-ting was applied for flow discretisation. The four stepRunge-Kutta algorithm was employed for advance-ment of solution in time. The time step was deter-mined from Courant-Friedrichs-Lewy condition, wherethe CFL number was equal to 0.2 to ensure stability.Results and discussion. Figure 1 presents the dy-namics of temperature and hydrogen mole fraction inthe initial stage after hydrogen releases into air. Themembrane rupture process is governed by the forma-tion of under-expanded jet from the membrane withincreasing in time open fraction of the tube cross sec-tion. A barrel-like structure can be seen. The openingof the next concentric ring of the burst disk generatesbarrel of larger diameter and the flow pattern lookssimilar to the diamond-like shapes. For the case of in-stant opening of the non-inertial membrane the shockheated zone is almost three times thicker compared tothe inertial membrane rupture case at the same mo-ment of time. The inertial opening of the membranegenerates more mixing between hydrogen and air, es-pecially in the boundary layer of the tube walls. Maxi-mum temperature in the shock-heated air is 50 K lowerfor the case of inertial membrane opening.Conclusions. The initial dynamics of temperatureand mixing of hydrogen with air in the PRD main tubefollowing the burst disk rupture is studied. The com-parison of membrane and instant openings of a burstdisk was carried out. It was shown that for the case114Physics of Extreme States of Matter—2010 / Eds. Fortov V. E. et al. Chernogolovka: IPCP RAS, 2010. P. 113–115c© Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 2010of instant opening, shock heated zone is almost threetimes thicker compared to the inertial membrane rup-ture case at the same moment of time. The inertialopening of the membrane generates more mixing, es-pecially in the tube wall boundary layer. Maximumtemperature in the shock-heated air is 50 K lower forthe inertial membrane opening case. Shock wave prop-agates faster for the non-inertial membrane.1. Lenkevich D.A., Volodin V.V., Golub V.V. et al. //Proc. FLUCOME10, Moscow, 17–21 August, 2009.2. Wolanski P., Wojcicki S. // Proc. Comb. Inst. 1972.V. 14. P. 1217.3. Bazhenova T.V., Bragin M.V., Golub V.V. et al. //Proc. 25 ISSW, 17–24 July, 2005, Bangalore.4. Bazhenova T.V., Bragin M.V., Golub V.V. et al. //Tech. Ph. Let. 2006. V. 32. P. 269.5. Liu Y. -F., Tsuboi N., Sato H. et al. // Proc. 20ICDERS, 31 July–5 August 2005, Montreal.6. Xu B.P., El Hima L., Wen J.X. et al. // J. Loss Prev.Proc. Ind. 2008. V. 21. P. 205.7. Dryer F. L., Chaos M., Zhao Z. et al. // Comb. Sci.Tech. 2007. V. 179. P. 663.8. Mogi T., Shina H., Kim D. et al. // W–i–P poster 31Int. Symp. Comb. 6–11 August 2006, Heidelberg.9. Mogi T., Kim D., Shina H. et al. // J. Loss Prev.Proc. Ind. 2008. V. 21. P. 199.10. Golub V.V., Baklanov D. I., Bazhenova T.V. et al. //J. Loss Prev. Proc. Ind. 2007. V. 20. P. 439.11. Golub V.V., Baklanov D. I., Golovastov S.V. et al. //J. Loss Prev. Proc. Ind. 2008. V. 21. P. 185.12. Pinto D., Aizawa K., Liu Y. F. et al. // Proc. 21ICDERS, 23–27 July 2007, Poitiers.13. Wen J.X., Xu B.P., Tam .Y. // Comb. Flame. 2009.V. 156. P. 2173.14. Lee B. J., Jeung I. –S. // Int. J. Hyd. En. 2009. V. 34.P. 8763.15. Bragin M., Molkov V. // Proc. 3 ICHS, 16–18 Septem-ber 2009, Ajaccio. Paper 265.16. Molkov V., Makarov D., Schneider H. // J. Phys. D:App. Phys. 2006. V. 39. P. 4366.17. Magnussen B. F. // Proc. 19 AIAA, 12–15 January1981, St. Louis.18. Gutheil E., Balakrishnan G. and Williams F.A. // Re-duced kinetic mechanisms for applications in combus-tion systems / Eds. Peters N., Rogg B. New York:Springer–Verlag, 1993. P. 179.19. Spence D.A., Woods B.A. // J. Fl. Mech. 1964.V. 19. P. 161.FLAME EVOLUTION WITHIN CLOSED VOLUMESIvanov M.F., Kiverin A.D.∗, Rikov Yu.V.JIHT RAS, Moscow, MIPT, Dolgoprudny, Russia*alexeykiverin@gmail.comIntroduction. Combustion gasdynamics withinconfined volumes studying is a basis for the opti-mum fuel combustion regimes design. The optimalityis necessary when engine combustor or other energy-producing technical system is elaborating. It definespermanent interest in gaseous combustion within chan-nels and tubes. A number of studies [1–3] concernflames propogating within opened and semi-openedchannels. It allowed to gave a sufficiently detailed anal-ysis of Darrieus-Landau (DL) instability—the leadingfactor defining laminar flame evolution.It is principle point that patterns of DL-instabilityevolution obtained in studies with different bound-ary conditions prescribed on channel walls are ratherdifferent. Thus, in case of gas slip boundary condi-tions on the walls one can observe instability stabi-lization in time, the process becomes stationary andthe flame front takes the quasi single-mode form [1].In case of no-slip boundary conditions a highly per-turbed wrinkled flame structure is formed, the flamefront takes fornicated or tulip-shaped forms [2]. No-slip condition seems to be more natural because itis in agreement with molecular-kinetic theory resultsfor gas interaction with solid surfaces. However ex-perimental photos of gas mixture combustion in chan-nels indicate existence of both quasi single-mode [4]and fornicated/tulip-shaped flames [5]. Accountingfor the same mechanism of gas-surface interaction formost gases one can assume that in the real situationthe flame front evolution depends on the specific com-bustible mixture composition not only quantitativelybut qualitatively as well. In addition distinctions haveto be observed for different channel widths [6, 7] andin presence of obstacles [6, 8].The chambers walls are natural obstacles. Thereforeflame dynamics within fully closed channel is distinctfrom dynamics within opened and semi-opened chan-nels. It is defined by more complex combination ofphysical processes. Equally with intrinsic instabilitiesflame front is affected by acoustic waves generated bypropagating flame itself and repeatedly reflected fromthe channel walls. In this case flame propagates inconditions of upwind flows and permanently growingpressure due to energy release within closed volume.Combined influence of flame instability and acousticperturbations creates sufficiently complex evolution ofthe flame front propagating through the channel.This paper represents numerical investigation offlame propagation in channels on the basis of hydro-gen bearing combustible mixtures as an example. Thecomparative analysis of flame propagation in semi-opened and fully closed channels of different widthsand lengths was carried out. Channels were filled withhydrogen-air or hydrogen-oxygen stoichiometric mix-tures. No-slip conditions were prescribed on side wallsof the channel. The numerical algorithm used is basedon a mathematical model that describes the gas dy-namics of real combustible mixtures in detail. De-tailed model allowed to compare combustion dynamicsin mixtures of different compositions [9].Results. Analysis and discussion. Analyzingnumerical modeling results (Fig. 1, 2) one can markout three main stages of flame evolution in no-slip-walled channel. The first stage take place immedi-115Physics of Extreme States of Matter—2010 / Eds. Fortov V. E. et al. Chernogolovka: IPCP RAS, 2010. P. 113–115c© Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 2010

The effect of burst disk opening on combustible mixture formation preceeding hydrogen spontaneous ignition

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The effect of burst disk opening on combustible mixture formation preceeding hydrogen spontaneous ignition

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