2004 Progress Report: Flow Control and Design of Environmentally Benign Spray SystemsEPA Grant Number: R829587
Title: Flow Control and Design of Environmentally Benign Spray Systems
Investigators: Plesniak, Michael W. , Frankel, Steven H. , Sojka, Paul E.
Current Investigators: Plesniak, Michael W. , Frankel, Steven H. , Shu, Fangjun , Sojka, Paul E.
Institution: Purdue University
EPA Project Officer: Richards, April
Project Period: January 1, 2002 through December 31, 2004
Project Period Covered by this Report: January 1, 2004 through December 31, 2005
Project Amount: $350,000
RFA: Technology for a Sustainable Environment (2001) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
The objective of this research project is to reduce air pollutant emissions by improving droplet transfer efficiency (i.e., reducing overspray and hence reducing particulate and solvent effluents in spray coating processes).
The working hypothesis is that increasing the turbulence intensity near the target surface will enhance in the deposition of small paint droplets, which would normally be swept away by the flow parallel to the target, resulting in overspray. The method chosen to enhance turbulence is a passive method in which specially shaped nozzles (i.e., nozzles of indeterminate origin [IO]), are used to promote turbulence.
The mechanisms by which IO nozzles influence the jet’s turbulence structure and evolution were investigated. Quantitative Particle Image Velocimetry (PIV) measurements were performed for a free jet and impinging jet, which models the basic stagnation flow configuration representative of a paint spray impinging upon the surface to be painted. The IO nozzles have maximum influence on jet structure in the near-nozzle region (within several nozzle diameters), but the effects decay with downstream distance. The IO nozzle influences the jet structure by introducing streamwise vortex pairs that interact with the turbulent structures present in the jet. As the jet propagates downstream, the streamwise vortices weaken and their effect diminishes, so it remains to be determined whether such passive control of the turbulence at the nozzle will persist to yield beneficial effects on drop transfer efficiency at the target. The following specific accomplishments were achieved: (1) PIV measurements of velocity field and data analysis; (2) baseline plain nozzle and optimum IO nozzle (truncated conical 4-point crown nozzle or TC4P nozzle) free jet; (3) baseline plain nozzle and optimum IO nozzle impinging jet; and (4) understanding the flow physics and development of IO nozzle jet.
In the next year, we will: (1) measure and compute two-phase water-particle jets; (2) perform large eddy simulations of two-phase flows; and (3) evaluate IO nozzles in actual sprays.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other project views:||All 14 publications||3 publications in selected types||All 3 journal articles|
||Shu F, Plesniak MW, Sojka PE. Frontispiece: Visualization of streamwise vortex pairs in an indeterminate origin (IO) nozzle jet. Journal of Visualization 2005;8(3):195.||
||Shu F, Plesniak MW, Sojka PE. Indeterminate-origin nozzles to control jet structure and evolution. Journal of Turbulence 2005;6(26):1-18||