STEAM STEAM means Steam Traction Engineering Analysis Method
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STEAM
• STEAM means: • Steam Traction Engineering Analysis Method • It’s a bit corny, but at least it means something!
What is it? A spreadsheet which can be used to predict: • Locomotive Performance: – Indicated Output – Wheel Rim Output – Drawbar Output – Steam Consumption • Indicator Diagrams • Exhaust Conditions
Origins • Started as a means for assessing forces acting on the locomotive frame. • Evolved to include additional parameters (e. g. steam properties, speed). • Still “Work in Progress”
How it Works • Calculates what happens through one complete wheel revolution in 1 Degree increments. • Uses inputs (valve events, steam chest pressure, cut-off) to generate an Indicator Diagram. • Calculates net piston force, forces on axleboxes, torque at driving axle, tractive effort and work done through the wheel revolution. • Inclusion of a speed parameter allows indicated power to be calculated. • Steam properties allow steam consumption to be calculated. • Resistance formula allow wheel rim and drawbar outputs to be found.
New Features on Version 4 d • Use of embedded steam tables. • Improved method of calculating steam consumption. • A “Generation Steam” Factor which allows locomotives with poorer front end design to be analysed. • Exhaust Steam temperature calculation. • Revised resistance calculation.
Validation Results compared with data from: • The “Red Devil” • Rugby Testing Station results • Swindon test plant results • Other data from Holcroft / Chapelon etc. • Dr Pawson’s work with “perform” Results typically within +/- 5% of Rugby Data and the “Red Devil” (with exceptions!) IHPs comparable to “perform”
Potential • A quick and easy to use (once you know it!). • A simple method by which design changes can be assessed. • A tool by which locomotive designs can be optimised. • Calculations are accessible – easy to fudge and look at “what if” scenarios. • Can be used to assess compounds.
Future Developments • • Boiler and Draughting calculations based on FDCs. Inclusion of reciprocating mass calculation. Provision for additional cylinders. Model the entire locomotive!
