Accession Number : ADA259459


Title :   Injection of Drag-Reducing Additives Into Turbulent Water Flows. Investigation of Laser-Induced Fluorescence for Concentration Measurements


Descriptive Note : Final rept. 1 Dec 90-15 May 92,


Corporate Author : PURDUE UNIV LAFAYETTE IN SCHOOL OF MECHANICAL ENGINEERING


Personal Author(s) : Schwarz, Andreas C ; Tiederman, William G


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259459.pdf


Report Date : Dec 1992


Pagination or Media Count : 67


Abstract : The concentration measurements of injected fluid in a turbulent water flow require a non-intrusive, high speed technique in order to capture the high frequency. concentration fluctuations without disturbing the flow. A Laser- Induced Fluorescence (LIF) technique was evaluated where special attention was directed towards the theoretical background and its application in the laboratory. Concentration measurements were performed during the injection of dyed water and a dyed, aqueous solution of a polyacrylamide into a fully- developed turbulent channel flow. A mass balance performed on a two-dimensional control volume using independent measurements of the streamwise velocity and the mean concentration yielded a significant deficit. Since it was unreasonable to attribute the imbalance to uncertainties in the measurements of the streamwise velocity, the main objective of this study was to carefully evaluate the concentration measurement technique. After having investigated the performance of the injector slot with respect to uniform injection, different experimental parameters that have an impact on the concentration measurements were varied. In the case of water-injected flow, it could be shown that the instantaneous array voltages have to be kept within a certain range which has to be determined prior to the experiment and depends on the saturation of the photo-diodes which are charged-coupled devices. In the case of polymer-injected flow, the additional issues that influence the evaluation of the mass flux are nonuniform injection and a displacement of the probe volumes in the high concentration, near-wall region.


Descriptors :   *LASER INDUCED FLUORESCENCE , *TURBULENT BOUNDARY LAYER , VELOCITY , DIODES , FREQUENCY , CONTROL , INJECTION , MEASUREMENT , TWO DIMENSIONAL , MASS , SLOTS , BALANCE , SATURATION , REGIONS , LASERS , VOLTAGE , BOUNDARY LAYER , ARRAYS , DISPLACEMENT , NONUNIFORM , UNIFORMS , ATTENTION , CHANNEL FLOW , DRAG , INJECTORS , MEAN , POLYACRYLAMIDES , FLOW , LABORATORIES , FLUIDS , ADDITIVES , BACKGROUND , WALLS , POLYMERS , PARAMETERS , PROBES , UNCERTAINTY , VOLUME , HIGH FREQUENCY , IMPACT


Subject Categories : Radiation and Nuclear Chemistry
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE