Atomizing Air Flow Rate Research Articles

Active control for gas turbine combustors

Closed-loop feedback control is implemented in two model combustors as a demonstration of the application of feedback control to gas turbine combustion. The first combustor is an axi-symmetric, swirl-stabilized, spray-fired combustor, while the second combustor incorporates discrete wall injection of primary and dilution air, representative of an actual gas turbine combustor. In both combustors, the emission of carbon monoxide and carbon dioxide, the radiative heat flux to the liner associated with soot and combustor stability are monitored in real time and controlled as a function of combustor load. The control input to the system is the nozzle atomizing air flow rate. The emission of carbon monoxide and carbon dioxide, the radiative flux to the liner, and the combustor stability are obtained through non-intrusive radiometric sensors mounted near the combustor exit plane. This information is conveyed to a control computer which invokes an optimization algorithm to minimize the CO and soot radiative flux, while maximizing the CO 2 radiative flux. The index of combustion instability (onset of elevated acoustic emission) is, in the present case, a characteristic frequency in the power spectral density of the CO signal. The identical control methodology is applied to the two combustors with satisfactory and promising results that demonstrate the potential of active control to practical systems.

Drop Size Distribution and Air Velocity Measurements in Air Assist Swirl Atomizer Sprays

Detailed measurements of mean drop size (SMD) and size distribution parameters have been made using a Fraunhofer diffraction particle sizing instrument in a series of sprays generated by an air assist swirl atomizer. Thirty-six different combinations of fuel and air mass flow rates were examined with liquid flow rates up to 14 lbm/hr and atomizing air flow rates up to 10 lbm/hr. Linear relationships were found between SMD and liquid to air mass flow rate ratios. SMD increased with distance downstream along the center line and also with radial distance from the axis. Increase in obscuration with distance downstream was due to an increase in number density of particles as the result of deceleration of drops and an increase in the exposed path length of the laser beam. Velocity components of the atomizing air flow field measured by a laser anemometer show swirling jet air flow fields with solid body rotation in the core and free vortex flow in the outer regions.

Effects of Spray Pyrolysis Conditions on Character of Yttria Partially Stabilized Zirconia Powders

Fine yttria-partially-stabilized zirconia powders were prepared by the spray pyrolysis method from a water: alcohol solution of ZrO(NO3)2⋅2H2O and YCl3⋅6H2O corresponding to 2mol% Y2O3. Effects of flow rates of atomizing air and solution, concentration of solution and reaction furnace temperature on the powder properties such as particle size, specific surface area, crystallite size and crystalline phase of as-synthesized powders were examined. It was observed that the as-synthesized powders are tetragonal phase containing 2±0.3 mol% Y2O3. The particle size was 0.2-5μm and a particle was agglomerates of fine crystallite of 165-210A in size. The powder consisted of hollow spherical or lath like particles and the specific surface area was 3-11m2/g. The size of agglomerate decreased with increasing atomizing air flow rate, of which the pyrolysis was independent. With increasing rate of solution, the size of agglomerate increased, but this size was not sensitive to the increase in the concentration of solution. In both cases, the pyrolysis of the salts was incomplete. A similar phenomenon was observed in the powder preparation at low temperatures.

Laboratory studies on sulphur‐coating urea by the spouted bed process

AbstractA spouted bed facility, which includes a 0.154 m ID x 0.91 m high bed with a 60° conical bottom, was used for the batch‐wise production of sulphur coated urea. Molten sulphur was sprayed into the cone and the droplets froze upon impact with the cooler urea particles thereby forming coats which increased with time.The quality of the coated urea was studied as a function of bed temperature (48–86 C), sulphur flow rate (34–260 g/min), atomizing air flow rate (0.402–0.785 m3/hr) and bed depth (0.28–0.47 m). No attempt was made to seal the product with wax or other materials. Bed temperature had the greatest effect on product quality, with quality improving up to approximately 80 C and then decreasing again. The quality also increased with the sulphur flow rate and decreased with the atomizing air flow rate. These measurements are explained in terms of the phase transition from monoclinic to orthorhombic sulphur and the sulphur droplet size which influences the spreading of liquid sulphur on impact with the urea particles. Electronmicrographs are presented in support of these explanations and the implications of the results for commercial sulphur coating facilities are discussed.

A comparative study of the structure of burning sprays of number 2 and SRC-II fuel oils

This paper deals with a comparative-experimental study of the flame structure of the air-blast atomized sprays of number 2 fuel oil (petroleum derived) and SRC-II fuel oil (coal derived). The effects of fuel flow rate, atomizing air flow rate, and swirling air flow rate on the following flame characteristics have been studied: flame appearance and length, axial and radial profiles of temperature, concentration of major species CO 2, H 2O, O 2, and CO, concentration of oxides of nitrogen and particulates, and radiant power emission. The results indicate that gross flame properties and the effects of operating variables on them in SRC-II and number 2 fuel oil flames are qualitatively similar. The magnitudes of flame radiation, particulate concentration, and nitrogen oxide concentrations are higher and peak temperatures are lower in SRC-II oil flame than in number 2 oil flame.