Subproject A06N - Experimental investigation of the interaction between scalar transport and turbulence on walls

Link SFB/TRR150: https://www.trr150.tu-darmstadt.de/index.de.jsp

In this new subproject the interaction between scalar transport and turbulence at walls will be investigated experimentally. The arrangement consists of a nozzle with a separation wall in the middle. The two partial flows propagate after nozzle exit at a certain distance against a wall perpendicular or inclined to the flow direction.

The superordinate scientific question of the planned investigations in the generic flow configuration that is relevant to the engine and exhaust system is to investigate the momentum, heat and mass transfer near the wall when the gaseous shear layer between the two fluids is flowing towards it. For this purpose, laser diagnostic measurement techniques such as Planar Laser Induced Fluorescence (PLIF), Particle Imaging Velocimetry(PIV)/ParticleTracking Velocimetry(PTV) and (2-point) Laser Doppler Anemometry (LDA) will be used to determine the scalar and velocity fields. On the other hand, wall heat flows and temperatures are also determined with the aid of heat flow sensors, IR cameras, thermographic phosphors and thermocouples. By simultaneous use of the mentioned laser diagnostic measurement techniques, common, multi-dimensional PDFs (Probability Density Functions) of the form PDF(u(x),C(x),(x)) can be acquired. The PDFs contain the full statistical information of the flow within the respective measurement plane. From them, all statistical moments of velocities, concentrations and temperatures can be determined directly. The above quantities are to be obtained in the flow configuration by varying several parameters to change the boundary conditions, such as (I) turbulent Reynolds number Re_T, (II) angle of attack of the wall, (III) variation of the flow in terms of density, temperature and velocity in both inflows of the nozzle, and (IV) the roughness and temperature of the wall. High turbulent Reynolds numbers are to be obtained with the help of active turbulence generators (up to Re_T~ 300-500). To characterize the turbulence, turbulence spectra or the length and time measures will be determined. The experimental data obtained in this subproject serve in particular the subprojects B02 and B03 for model development and validation. The experiment thus serves both numerical subprojects as a generic experiment for chemically non-reacting flow-wall interactions.