The structure andextinctionbehaviorofpartiallypremixed  ames ina counter owconŽ gurationare investigated by using Ž ve different chemistry models. These include the C1 and C2 mechanisms of Peters and Rogg (Peters, N., and Rogg, B., Reduced Kinetic Mechanisms for Applications in Combustion Systems, Springer–Verlag, Berlin, 1993, pp. 8–12), a 12-step augmented reduced mechanism, andGRI-2.11 and...

Compressible gas flow inside a convergent-divergent nozzle and its exhaust plume atdifferent nozzle pressure ratios (NPR) have been numerically studied with severalturbulence models. The numerical results reveal that, the SST k–ω model give the bestresults compared with other models in time and accuracy. The effect of changes in value ofdivergence half-angle (ε ) on the nozzle performance, thru...

Nozzle shape plays a key role in determining the flow pattern in the mold of the continuouscasting process under both steady-state and transient conditions. This work applies computational models and experiments with a one-third scale water model to characterize flow in the nozzle and mold to evaluate well-bottom and mountain-bottom nozzle performance. Velocities predicted with the three-dimens...

The objective of this paper is to computationally analyse shock waves in the Convergent Divergent (CD) Nozzle. The commercial CFD code Fluent is employed to analyse the compressible flow through the nozzle. The analysis includes static pressure, temperature, Mach number and density of the flow for different nozzle pressure ratios (NPR i.e., the ratio between exit pressure of the nozzle to ambie...

A theoretical study analyzing three-dimensional combustion acoustic instabilities in a liquid propellant rocket engine combustor has been conducted. A linear theory based on Crocco’s pressure sensitive time lag model is used. To apply this theory the combustor is divided into two main components, including the combustion chamber and the converging part of the nozzle. The assumption of concentra...

in this study, an electrostatic sprayer which had been previously designed and constructed was evaluated in order to quantify the charging of droplets. liquid atomization was achieved by using an ultrasonic nozzle. the nozzle maximum flow rate was 25 milliliters per minute and vibration frequency was about 30 khz. the induction method was used for charging the output droplets. all experiments w...

The two limits, “frozen” and “equilibrium” flow share an important property: both are isentropic flows (if we ignore friction or heat losses). This is because, in the frozen case no chemical change during expansion), there are no rate processes at all occurring, the molecules preserving their identity all the way, while in the equilibrium case, in which reactions do occur, their rate is so high...

A computational analysis of an annular converging-diverging (CD) and an altitude adaptive expansion-deflection (ED) nozzle is presented. Numerical results were generated using a 2D axisymmetric, pressure-coupled solver in conjunction with the Spalart-Allmaras turbulence closure model and second order spatial discretisation schemes. Results were recorded over a theoretical altitude range and com...

In a continuing effort to study the mixing enhancement by large-scale streamwise vortices generated by a lobed nozzle, a high-resolution stereoscopic particle image velocimetry ~PIV! system was used in the present study to conduct three-dimensional measurements of air jet flows exhausted from a lobed nozzle and a conventional circular nozzle. The three-dimensional instantaneous and ensemble-ave...

The near-field structure of strongly buoyant jet issuing from a square nozzle at low Froude and Reynolds numbers is studied by using three-dimensional LIF flow visualization and scanning PIV. These experimental techniques allow the visualization of unsteady three-dimensional flow phenomenon occurring in the near-field of strongly buoyant jet. It is found that the buoyant jet is unstable to the ...