Diesel Exhaust Plume Behavior

1/15 Scale Wind Tunnel Model Locomotive at 10º Yaw Exhaust Plume Visualization

Abstract

Fluid dynamic simulations were performed for a variety of locomotives operating under a number of ambient conditions, including variations in wind speed and direction.  The concentration of diesel exhaust at the operator cab window were quantified

Objectives

1. Identification of typical switchyard and line-haul locomotives. 
• The Car and Locomotive Cyclopedia of American Practices
• Locomotive manufacturer specifications
• Inventories of locomotives in various railroad fleets
• Interviews with industry experts.
2. Complete analysis of U.S. railroad track survey data.
3. Evaluation crosswind conditions (wind yaw angles) within switchyards and for line-haul operations.
4. Identify typical locomotive throttle (notch) positions and train speeds for both switchyard and line-haul operations.  These were used to calculate representative exhaust flow rates.
5. Define diesel exhaust characteristics (flow rates, composition, and temperature) for a variety of locomotives.
6. Perform diesel-electric locomotive exhaust plume behavior studies:
• Field tests
• Wind tunnel tests
• Computer simulations of diesel locomotive exhaust plume behavior.
7. Quantify concentrations of exhaust gas components and particulate matter at the leeward side windows of locomotives operating in both switchyard and line-haul conditions for a range of operating conditions.

Approach

Simulation Results

Low Speed Operation

High Speed Operation

Results and Conclusions

Exhaust and particulate concentrations were calculated at the cab windows of leading and trailing locomotives. Exhaust concentrations at the leading locomotive cab leeward-side window with the locomotives oriented with the long-hood-forward are 14 times greater than those at the same location when the locomotives are oriented with the short hood forward.