Experimental investigations of structure formation in turbulent mixed convective duct flows
Convective flows in rectangular ducts are of interest in many applications. The must obvious examples are the flow through heat exchangers or in cooling devices. The principle found in many industrial applications is forced channel flow heated from below, which is characterized by the interaction of buoyancy with a pressure-driven flow leading to complex three-dimensional and often turbulent mixed convection. A further complication arises from the temperature dependency of the fluid properties. Due to the complexity of this mutual interaction of the buoyancy-driven and forced flow the physical mechanisms involved are up to now not fully understood.
At the DLR Göttingen a generic heat exchanger channel has been developed in order to study the formation and dynamics of buoyancy induced flow structures and their influence on the forced flow. The partially transparent duct allows for optical flow measurement e.g. Particle Image Velocimetry, Schlieren photography or Laser Doppler Anemometry. In addition the apparatus is equipped with temperature sensors in order to study the flow structure dynamics and transport of heat as a function of the ratio of buoyancy to inertia forces, the aspect ratio of the duct and the fluid properties.
Dr. rer. nat. Andreas Westhoff
German Aerospace Center (DLR)
Institute of Aerodynamics and Flow Technology, Department Ground Vehicles
Phone: +49 551 709-2294