Download or read book An Improved Hydrogen/oxygen Mechanism Based on Shock Tube/laser Absorption Measurements written by Zekai Hong and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: H2/O2 combustion chemistry is the core of all hierarchical hydrocarbon combustion mechanisms. Because of this, H2/O2 combustion chemistry has been the target of extensive research and our understanding has been improved substantially over the years. However, there still remains a critical need for improvements and the development of an even higher fidelity H2/O2 mechanism. These improvements require the researcher to go beyond existing methodologies and to adopt new approaches and better tools. This thesis outlines the work carried out to produce such a high-fidelity mechanism. In particular, a three-part strategy was implemented: 1) new shock tube/laser absorption tools were developed, 2) rates constants of selected HO2/H2O2 reaction were measured, and 3) a new mechanism was developed and validated. 1) Within the scope of this dissertation work, two major tools were developed: a modified shock tube and a sensitive H2O diagnostic. A standard shock tube was modified to eliminate gradual temperature or pressure rises behind reflected shock waves due to non-ideal effects. Long and uniform test times were achieved with the modified shock tube behind reflected shock waves, where kinetics experiments were carried out. H2O time-histories behind reflected shock waves were recorded with an H2O laser absorption diagnostic part of whose development was also included in this study. Accurate knowledge of trace amounts of H2O in combustion systems provides a unique new capability in studies of combustion chemistry. In addition, an OH laser absorption diagnostic for OH that has been well-established in this laboratory was used in combination with the H2O diagnostic for a more thorough understanding of combustion kinetics. 2) The rate constants of four important reactions within the H2/O2 combustion system were experimentally determined. By combining the modified shock tube technique with the laser diagnostics for OH and H2O, various H2/O2 systems were studied to obtain more accurate rate constants for several important reactions at combustion temperatures, including: H + O2 = OH + O; H2O2 + M = 2OH + M; OH + H2O2 = HO2 + H2O; and O2 + H2O = OH + HO2. 3) An improved H2/O2 reaction mechanism was compiled that incorporated the aforementioned rate constant determinations, as well as recent studies from other laboratories. The new mechanism was tested against OH and H2O species time-histories in various H2/O2 systems, such as H2 oxidation, H2O2 decomposition, and shock-heated H2O/O2 mixtures, and was found to be in very good agreement. In addition, the current mechanism was validated against a wide range of more standard H2/O2 kinetic targets, including ignition delay times, flow reactor species time-histories, laminar flame speeds, and burner-stabilized flame structures.