2003 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, 2003 through December 31, 2004
Project Amount: $350,000
RFA: Technology for a Sustainable Environment (2001) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
The object 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).
Considerable progress was made in achieving the technical objectives for both the experimental and computational components of the investigation.
To provide a physical understanding of flow control for a spray process and to facilitate computational model development and a benchmark of numerical results, a simple canonical model flow was investigated first. Several building blocks that captured many of the relevant physical processes in spray coating were investigated. First, a large-scale water jet was constructed and probed extensively using laser induced fluorescence (LIF) flow visualization and particle image velocimetry (PIV) to examine the effects of nozzle geometry on the jet structure and spreading. (Solid particles will eventually be introduced into the jet to simulate the action of the smallest spray droplets, which are important to control to achieve increases in transfer efficiency).
The following specific accomplishments were achieved:
• Design and manufacture of new indeterminate origin (IO) nozzle exits
• LIF flow visualization of various configurations
• PIV measurements of velocity fields
- Baseline plain nozzle (free jet)
- Optimum IO nozzle free jet (modified 4-point crown nozzle).
Companion simulations also have been performed. The following specific objectives have been accomplished:
• Two-phase flow predictions for particle-laden impinging jets suggest that the crown nozzle increases the spreading rate of the jet.
• The Large Eddy Simulation (LES) predictions for the round-nozzle-produced impinging jet are in much better agreement with the experimental data than the previous Reynolds-Averaged Navier-Stokes/Reynolds Stress Model (RANS-RSM) results.
In the next year, we will perform the following measurements and simulations: (1) measurements and computations of two-phase water-particle jets, (2) large eddy simulations of two-phase flows, and (3) evaluation of IO nozzles in actual sprays.