HLRB Project pr84qo

Modulation of Turbulent Properties in a Spray Flame Burning n-Heptane Direct Numerical Simulation

Institute of Fluid Dynamics & Thermodynamics, Uni Magdeburg

Modulation of Turbulent Properties in a Spray Flame Burning n-Heptane Direct Numerical Simulation

Institute of Fluid Dynamics & Thermodynamics, Uni Magdeburg

Institute of Fluid Dynamics & Thermodynamics, Uni Magdeburg

Abouelmagd Abdelsamie

Universitätsplatz 2

39106 Magdeburg

The final objective of the current work is to investigate turbulent spray flames at high droplet density,quantifying possible modifications of the turbulent properties. As a first step, the modification ofturbulence statistics (kinetic energy, dissipation rate spectrum...), the auto-ignition process and the resulting flame structure are investigated in decaying turbulence by Direct Numerical Simulation (DNS) considering n-heptane liquid droplets. The droplets, being smaller than the grid resolution and Kolmogorov length scale, are modeled as point droplets, while the Navier-Stokes equations are solved in the low-Mach number regime. Detailed models are employed to describe chemical reaction and molecular transport in the gas phase. In the current DNS, the continuous (gas) phase is simulated in a standard manner (Eulerian frame) whereas the discontinuous (droplet) phase is tracked in a Lagrangian frame. Two-way coupling interaction between both phases is quantified via the exchange of mass, momentum and energy. The impact of different parameters is investigated, in particular: initial temperatures, equivalence ratio/droplet mass fraction, droplet size and turbulence level (with a Taylor Reynolds number up to 150). The Stokes drag force is dominant in the droplet momentum equation, whereas the evaporation process is computed by using a variable Spalding mass transfer number and an infinite conduction model inside the droplet. The in-house 3D DNS solver DINOSOARS is used for all simulations. An implicit time integration scheme is used for the chemistry source term. All kinetic and transport properties are handled in DINOSOARS using Cantera 1.8 and Eglib 3.4.

Impressum, Conny Wendler