Introduction to "To the Question of Energy Use of Detonation Combustion" By Ya. B. Zel'dovich
Ya. B. Zel’dovich (1914–1987) made numerous contributions [1] to the theory of detonation, beginning with his very well known and widely translated article [2] on detonation structure that first introduced the standard Zel’dovich-von Neumann-Doring (ZND) model of shock-induced combustion. Even at that early stage of detonation research, Zel’dovich was also considering the application of detonations to propulsion and power engineering. He published these ideas in another paper [3] that has been virtually unknown in the West and has apparently remained untranslated until now. We are indebted to Sergey Frolov of the N.N. Semenov Institute of Chemical Physics for first bringing this article to our attention. We believe that the focus of this paper, which is the application of detonation waves to power generation and propulsion, is very relevant to the current activity on pulse detonation engines. In particular, Zel’dovich was apparently the first researcher to consider the questions of the relative efficiency of various combustion modes, the role of entropy production in jet propulsion, and the distinction between unsteady and steady modes of detonation in power engineering and propulsion applications. Even 60 years later, we believe that his results are relevant and can be of value in modern discussions on thermodynamic cycle analysis of detonation waves for propulsion [4]. For these reasons, we have arranged for the paper to be translated and suggested that it be published by the Journal of Propulsion and Power.
Preparing for the Future: Reducing Gas Turbine Environmental Impact—IGTI Scholar Lecture
In the long term, the price of fuel will rise and it is now urgent to reduce carbon dioxide emissions to avoid catastrophic climate change. This lecture looks at power plant for electricity generation and aircraft propulsion, considering likely limits and possibilities for improvement. There are lessons from land-based gas turbines, which can be applied to aircraft, notably the small increases in efficiency from further increase in pressure ratio and turbine inlet temperature. Land-based gas turbines also point to the benefit of combining the properties of water with those of air to raise efficiency. Whereas the incentive to raise efficiency and reduce CO 2 will force an increase in complexity of land-based power plant, the opportunities for this with aircraft are more limited. One of the opportunities with aircraft propulsion is to consider the whole aircraft operation and specification. Currently the specifications for new aircraft of take-off and climb thrust are not fully consistent with designing the engine for minimum fuel consumption and this will be addressed in some depth in the lecture. Preparing for the future entails alerting engineers to important possibilities and limitations associated with gas turbines which will mitigate climate change due to carbon dioxide emissions.
Review of shock-induced supersonic combustion research and hypersonic applications
This article focuses on research in supersonic combustion and combustion kinetics in high-speed flow between 1959-1968, and the application of the experimental results to hypersonic propulsion. The analysis discusses both advantages and problems for premixing the fuel and employing shock-induced combustion as an ignition method for a scramjet flying at a high Mach number. The experimental tests are discussed, including implications to the chemical kinetics of the high-velocity combustion process. The conditions were confined to relatively low pressure, less than 2 atm (200 kPa). The results were considered to be mainly applicable for high-altitude scramjet flight, at low static pressure, where chemical reaction distances will be long. At these lower pressures, "shock-induced combustion" may be the predominant effect in a scramjet application, and it has some advantages that are discussed. The relation between shock-induced combustion and "detonation" is also discussed. In addition, an attempt is made to resolve the conflicting experimental data published in the 1960s relating to "standing detonation waves" and shock-induced combustion.