Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
DESIGN AND QUALIFICATION OF AN APPARATUS FOR THE EXPERIMENTAL STUDY OF LAMINAR SEPARATION BUBBLES
Submission Author:
omar elias horna pinedo , RJ , Peru
Co-Authors:
omar elias horna pinedo, Igor Braga de Paula
Presenter: omar elias horna pinedo
doi://10.26678/ABCM.ENCIT2018.CIT18-0198
Abstract
The present work involves the design, construction and performance test of an apparatus for the investigation of laminar separation bubbles in a flat plate boundary layer. Laminar separation bubbles are relevant for many engineering applications and the dynamic of such bubbles has a strong impact on the performance of aircrafts and turbines. The separated boundary layer reattaches to the surface due to the laminar-turbulent transition in the bubble region. This dynamic process is highly challenging for flow simulation tools used for engineering purposes. Thus, there is a demand for experimental studies that can be used for calibration of models present in simulation tools. To this end, an apparatus was designed and built for the water channel of the Laboratory of Fluid Engineering at PUC-Rio. The boundary layer separation on the flat plate was induced by imposing a constant adverse pressure gradient to the flow. To this end a false wall was built, in order to form a converging-diverging channel with the flat plate. Flow separation on the false wall was avoided using a suction mechanism that was designed to reduce locally the boundary layer thickness. Location of suction and suction flow rates were determined with aid of numerical simulations. In addition, it was designed and built a disturbance source to generate Tollmien-Schlichting waves in the boundary layer of the flat plate. This device was used to trigger the boundary layer transition in a controlled manner. All equipments were tested and their designs were validated against experimental measurements. Laser Doppler anemometry and Particle Image Velocimetry techniques were adopted for assessment of each equipment. Results validate the design and show that separation bubbles can be investigated in detail using this apparatus.
Keywords
laminar separation bubbles, Hydrodynamic Instability, laser doppler velocimetry, Particle image velocimetry
