Simultaneously combined liquid crystal surface heat transfer and PIV flow-field measurements

An experimental technique has been developed which combines simultaneous hi gh-density particle image velocimetry (PIV) with a new thermochromic liquid -crystal based instantaneous convective heat transfer sensing system. The n ew heat transfer sensing system employs liquid crystals applied to the non- flow side of a constant heat flux foil, and isolated from the support plate by a thin insulating cavity. The resulting composite sensing sheet is capa ble of a 66 Hz frequency response and, when utilized in a water flow, it ca n track instantaneous variations in convective heat transfer for turbulent flows. Placement of the liquid crystals on the non-flow side of the constan t heat flux foil also provides optical separation from the flow field, allo wing the simultaneous application of high image-density PIV measurements. A description of the experimental apparatus is provided along with a validat ion and uncertainty analysis of the combined technique. Selected quasi-thre e-dimensional constructs obtained using this new technique are presented fo r a variety of turbulent flow configurations.