Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

Applications of detonations to propulsion are reviewed. First, the advantages of the detonation cycle over the constant pressure combustion cycle, typical of conventional propulsion engines, are discussed. Then the early studies of standing normal detonations, intermittent (or pulsed) detonations, rotating detonations, and oblique shock-induced detonations are reviewed. This is followed by a brief discussion of detonation thrusters, lasersupported detonations and oblique detonation wave engines. Finally, a more detailed review of research during the past decade on ram accelerators and pulsed detonation engines is presented. The impact of the early work on these recent developments and some of the outstanding issues are also discussed.

Review of Propulsion Applications of Detonation Waves

The U.S. commercial space launch industry has changed considerably since the enactment of the Commercial Space Launch Amendments Act of 2004. FAA is required to license or permit commercial space launches, but to allow the space tourism industry to develop, the act prohibited FAA from regulating crew and spaceflight participant safety before 2012—a moratorium that was later extended but will now expire on September 30, 2015. Since October 2014, there have been three mishaps involving FAA licensed or permitted launches.

美聯邦航空廳(Federal Aviation Administration)의 航空機 製作檢査 制度의 現況

Hydrodynamic and hydromagnetic stability

A comprehensive review of measurements and data analysis of laminar burning velocities for various fuel+air mixtures

On the effective Lewis number formulations for lean hydrogen/hydrocarbon/air mixtures

Experimental study on the effect of N2, CO2, and steam dilution on the combustion performance of H2 and CO synthetic gas in an industrial gas turbine

Acomputational study is carried out to develop a fully implicit and time-accuratecomputational e uid dynamics code for the analysis of reactive e ow systems. Periodically oscillating shock-induced combustion around a blunt body in a stoichiometric hydrogen ‐air mixture is used as a validation problem of examining various numerical considerations. Euler equations and species conservation equations are used as the governing equations for the chemically reacting e ow. Spatial discretization of the governing equation is based on Roe’ s approximate Riemann solver with a MUSCL-type total variation diminishing scheme for higher-order spatial resolution. The secondorder-accuratetimeintegrationmethodisbasedonalower ‐uppersymmetricGauss ‐Seidelscheme,usingaNewton subiteration method and Steger ‐Warming e ux Jacobian splitting. As a e rst step of the validation procedure, simulations of experimental results were carried out to cone rm the reliability of the baseline method. In the next step, the general aspects of the baseline method were examined, including order of time integration, number of subiterations, and use of approximate e ux Jacobian splitting. Appropriateness of the grid system is also examined by using a grid ree nement study.

Computational Fluid Dynamics Algorithms for Unsteady Shock-Induced Combustion, Part 1: Validation

Anumerical study hasbeenconductedto investigatetheeffectofshockwaveson thesupersonichydrogen ‐airjet e ame stabilized in a Mach 2.5 circularcross-section combustor. Thenumerical model utilizes multispecies Navier ‐ Stokes equationswith detailed chemical reaction modelsand employsa k‐! shear stresstransport model. A wedge is mounted on the side wall of the combustor in order to e nd the interaction of the oblique shock waves with the hydrogen‐air jetlike e ame. The interaction between the shock waves and the mixing layer is classie ed according to the increasing tendency of the growth rate of the mixing layer downstream of the shock waves. It is found that the shock wavescreatea radially inward/outward aire owto thee ame and elongatea e ame-holding recirculation zone, and thus fuel ‐air mixing is enhanced signie cantly, resulting in improved combustion efe ciency. Also, the overall performance is investigated by changing the shock position and considering the mixing/combustion efe ciency and total pressure loss in a model scramjet combustor. Because there exists a tradeoff between the enhanced mixing/combustion efe ciency and the decreased total pressure recovery, it is suggested that the optimized shock position needs to be determined in order to obtain the maximum overall combustor performance using the overall performance index.

Numerical Study of Mixing Enhancement by Shock Waves in Model Scramjet Engine

Many theoretical and experimental studies have been conducted to investigate elements of swirl injector hydrodynamics, such as variations in liquid film thickness or air core diameter. From these studies, some theoretical relationships have been established through an approximate analytical solution of flow hydrodynamics in a swirl nozzle. However, experimental studies on elements such as the measurement of liquid film thickness have not produced conclusive results. In a swirl injector, the atomization process is significantly influenced by the liquid film thickness. Thus, it is possible to investigate the effects of various geometric parameters on spray characteristics through the measurement of liquid film thickness. We used a specially designed injector based on the electrical conductance method to measure the liquid film thickness accurately. The liquid film thickness was measured through precise calibration, and the accuracy of this measurement was demonstrated in comparison with previous theories and experiments. From these results, we present an empirical relation for the liquid film thickness by adding orifice length to an existing analytical equation. The variations and stability of the air core were also examined by visualizing the formation of the air core in the swirl chamber with a high-speed camera system. This study confirms that air core shape and liquid film thickness are directly related. Thus, study of the fluctuations of liquid film thickness under various geometric conditions can be applied to the analysis of internal flow.

http://iopscience.iop.org/article/10.1088/0957-0233/20/1/015403/pdf

Youngbin Yoon

Papers

On the effective Lewis number formulations for lean hydrogen/hydrocarbon/air mixtures

Experimental study on the effect of N2, CO2, and steam dilution on the combustion performance of H2 and CO synthetic gas in an industrial gas turbine

Computational Fluid Dynamics Algorithms for Unsteady Shock-Induced Combustion, Part 1: Validation

Numerical Study of Mixing Enhancement by Shock Waves in Model Scramjet Engine

Effect of geometric parameters on the liquid film thickness and air core formation in a swirl injector