Pomiar PIV przepływu niestacjonarnego w kadzi wirowej

Praca przedstawia problemy pomiarowe jakie powstały podczas zrealizowanego cyklu badań z wykorzystaniem techniki pomiaru bezkontaktowego PIV (Particle Image Veolcimetry) przepływu niestacjonarnego w zbiorniku modelowym kadzi wirowej zwanej potocznie whirlpoolem. Obiektami badań były zbiorniki wykonane z PMMA o zróżnicowanym konstrukcyjnie rozmieszczeniu otworów wlotowych. W pracy zaprezentowano zbudowane stanowisko pomiarowe, sposób kalibracji, problemy i ograniczenia zastosowania PIV powstałe podczas prowadzenia badań oraz przykładowe wyniki analiz.

The paper presents measurement problems which occurred during the series of research incorporating the PIV (Particle Image Velocimetry) optical measurement of unsteady flow inside a scale model of a cycling vat, also known under the name of whirlpool. The subject of the research were containers made of PMMA with structurally diversified placement of inlets. The work unveils the workbench, the calibration method and the limitations of adopting PIV met during the research, along with sample results of analysis. The measurements were taken on a workbench built in the laboratory of Philadelphia Mixing Solutions, Palmyra PA, US. The measurements incorporated a PIV FlowSense2M camera, a DantecDynamics’ HUB system as well as YAG NewWave Solo 120 TX laser equipped with a controller, a part of which is a water-cooling system. FlowManager was the software used for computation, whereas DynamicStudio was used for analysis and result collection. While obtaining measures an array of difficulties was met, related to capturing decent quality images with seeding particles under specific conditions of filling up the whirlpool tank. The phenomenon of free surface inside the flow and the characteristics of filling up an open tank have revealed multiple complications connected to laser beam reflections along with capturing reflections from other light sources. An addi-tional trouble was caused by aeration of the mixture being the subject of the measurement. Unsteady flow was the cause of problems during analysis of the material, so it was necessary for adaptive correlation to be based on two frames. This is not the case with steady flow, for which we can use 1000 consecutive frames as a basis for the statistic analysis.