Open Access Journal Journal of Power Technologies 91 (3) (2011) 130–135 Cellular structure of detonation wave in hydrogen-methane-air mixtures Rafal Porowski, Andrzej Teodorczyk * Institute of Heat Engineering, Warsaw University of Technology 21/25 Nowowiejska Street, 00-665 Warsaw, Poland Abstract The paper reports on an experimental study of the cellular structure of detonation waves in hydrogen-methane- air mixtures. Experiments were performed in a 6-m circular cross section tube with inner diameter of 140 mm (full diameter of 170 mm) and a 0.8-m driver section tube with inner diameter of 90 mm. The initial conditions of stoichiometric hydrogen-methane-air mixtures were 1 atm and 293 K with varoius hydrogen content. The average detonation cell size for stoichiometric hydrogen-methane-air mixtures obtained by the smoked foil technique during the experiments was calculated with the 2D Fourier transform. Using the Cantera program, the detonation cell width was computed as a function of initial pressure and molar methane fraction in fuel for a stoichiometric methane-hydrogen-air mixture at initial temperature 295 K. The results of the computations were compared against the experimental results. Keywords: Detonation, Cell Size, Cellular Structure, Hydrogen, Methane 1. Introduction An increasing interest is being shown in methane, a main component of natural gas (ca 90%), as an al- ternative fuel. This is motivated by a general desire to reduce exhaust emissions. Whereas natural gas seems to be the cleanest of all the fossil fuels [1], hy- drogen too has been investigated as a single fuel in many experimental studies. Unfortunately, hydrogen is very difficult to store, handle and transport on the scale required by industry due to its low density, ex- tremely low boiling point (at 1 atm: -253 ◦ C or 20 K) and wide range of flammability limits (from 4% to 75%). That is why a hydrogen-methane mixture is used in a variety of combustion devices such as ICE engines (e.g. HCCI), gas turbines, various types of * Corresponding author Email addresses: (Rafal Porowski ), (Andrzej Teodorczyk ) burners with premixed and diffusion flames and in public pipeline transport. Another factor militating against hydrogen is the virtual absence of infrastruc- ture anywhere in the world for transporting hydro- gen gas. The construction of extensive pipeline net- works for hydrogen gas comparable to the existing natural gas pipeline networks would require massive investment. Although it is conceptually possible to provide financing for dedicated hydrogen pipelines, construction of extensive hydrogen networks is not expected in the short term. An alternative that at least merits discussion is the partial use of the ex- isting natural gas pipelines to transport hydrogen. Adding hydrogen to a methane-air mixture increases the flammability limits and stability ranges of the flame. It also decreases autoignition delay times and emissions of exhaust gases. Unfortunately, the pres- ence of hydrogen in flammable mixtures dramati- cally increases the risk of explosion and in particular