The basic principles of laser induced fluorescence are described with progressive presentation of simple and multi-level interaction schemas providing the relationship between the fluorescence signal and the local concentration of the investigated species in the laser field. Essential differences between laser induced fluorescence and flame chemiluminescence emissions are given. Techniques for ...

Large-eddy simulation (LES) has traditionally been restricted to fairly simple geometries. This paper discusses LES of reacting flows in geometries as complex as commercial gas turbine engine combustors. The incompressible algorithm developed by Mahesh et al. (J. Comput. Phys., 2004, 197, 215–240) is extended to the zero Mach number equations with heat release. Chemical reactions are modeled us...

We present a study of the flame-embedding concept, introduced in [1] as an efficient approach for large-eddy simulation of turbulent combustion at high Reynolds and Damköhler numbers. In flame embedding, the combustion zone is modeled as an unsteady flame modified by the local tangential strain rate, with the latter extracted every time step from the flow field simulations. The flame structure ...

Turbulence structure on the gas side of a wavy stratified flow was experimentally investigated in a near horizontal 18.7 cm (H) 10 cm (W) 5.5m (L) rectangular duct.By applying the Variable Interval Time Averaging (VITA) technique to the hot wire anemometer measurements frequency of occurrence of turbulent events were detected near the air-water interface. Experimental results showed that fr...

An easy-to-interpret kinematic quantity measuring the average corotation of material line segments near a point is introduced and applied to vortex identification. At a given point, the vector of average corotation of line segments is defined as the average of the instantaneous local rigid-body rotation over ‘all planar cross-sections’ passing through the examined point. The vortex identificati...

The two components of combustion noise, namely the direct noise induced by heat release fluctuations in the flow and the indirect noise caused by acceleration of entropy perturbations through mean flow gradients resulting in acoustic radiation, are examined by considering different types of inhomogeneous wave equations deduced from the balance equations of fluid dynamics. This is accomplished b...

Experiments were conducted to study the effects of heat release in a planar, gas-phase, reacting mixing layer formed between two free streams, one containing hydrogen in an inert diluent, the other, fluorine in an inert diluent. Sufficiently high concentrations of reactants were utilized to produce adiabatic flame temperature rises of up to 940 K (corresponding to 1240 K absolute). The temperat...

A novel computational methodology, termed “Irregularly Portioned Lagrangian Monte Carlo” (IPLMC) is developed for large eddy simulation (LES) of turbulent flows. This methodology is intended for use in the filtered density function (FDF) formulation and is particularly suitable for simulation of chemically reacting flows on massively parallel platforms. The IPLMC facilitates efficient simulatio...

In the present study, flow over flat and pooled stepped spillways was simulated three dimensionally. The VOF method and k- ε (RNG) turbulent model was used to simulate the flow over the stepped spillway. The results indicated that the numerical model was acceptably capable of simulating the flow over the pooled and flat stepped spillways for different discharges. Following that, the effect of d...