Measurement of spray combustion processes

A free jet configuration was chosen for measuring noncombusting spray fields and hydrocarbon-air spray flames in an effort to develop computational models of the dynamic interaction between droplets and the gas phase and to verify and refine numerical models of the entire spray combustion process. The development of a spray combustion facility is described including techniques for laser measurements in spray combustion environments and methods for data acquisition, processing, displaying, and interpretation

Mean velocity and turbulence measurements in a 90 deg curved duct with thin inlet boundary layer

The experimental database established by this investigation of the flow in a large rectangular turning duct is of benchmark quality. The experimental Reynolds numbers, Deans numbers and boundary layer characteristics are significantly different from previous benchmark curved-duct experimental parameters. This investigation extends the experimental database to higher Reynolds number and thinner entrance boundary layers. The 5% to 10% thick boundary layers, based on duct half-width, results in a large region of near-potential flow in the duct core surrounded by developing boundary layers with large crossflows. The turbulent entrance boundary layer case at R sub ed = 328,000 provides an incompressible flowfield which approaches real turbine blade cascade characteristics. The results of this investigation provide a challenging benchmark database for computational fluid dynamics code development

Development of a high-energy crowbar for the Los Alamos free-electron laser

A 135-kV, 2.5-..mu..s crowbar has been developed to protect the TH2095A klystrons used on the Los Alamos free-electron laser. The klystron power supply consists of a 135-kV, 8.75-..mu..F capacitor bank with a stored energy of approximately 80 kJ. The TH2095A specifications require that the dissipated energy in a klystron arc be limited to less than 10J. The crowbar design is based upon a series stack of pressurized spark gaps immersed in an oil tank. The spark gaps are triggered by an SCR-switched high-voltage trigger transformer. Input triggers are provided by current-monitoring transformers. The following currents are sensed for input triggers: total system current, integrated system current (long pulse sensing), cathode current, and modulator-anode current. Trigger levels are set to approximately 150% of nominal current levels. Unique features of this design are its modulator-anode trigger, noise immunity, and ability to print out the energy dissipated in the klystron arc. Typical operation of this system limits the energy dissipated in an arc to less than 2J. This paper describes the original design requirements, mechanical layout and fabrication, main trigger circuit design, modulator-anode trigger design, noise immunity circuit, integrated energy monitor, diagnostics, and recent developments. Performance data are also included. 1 ref., 6 figs