1. ME 475/675 Introduction to Combustion Lecture 40

2. Announcements Final: Friday, December 12, 2014, 2:45-4:45 PM HW17 Ch. 10 () Due Monday, 12/8/2013 Term Project (3% of grade), Due December 8 or 9? Instructions: http://wolfweb.unr.edu/homepage/greiner/teaching/MECH.475.675.Combustion/TermProjectAssignment.pdf Times to meet with Rachel Green about projects, HREL 305 Wednesday 12/3 12 – 5 pm Thursday 12/4 1 – 4pm Saturday 12/6 10 am – 3 pm Sunday 12/7 10 am – 3 pm Monday 12/8 12 – 5 pm Schedule other times by emailing rmgreen@unr.edurmgreen@unr.edu

3. Ch. 10 Droplet Evaporation and Burning

4. Applications: Diesel Engines Diesel Fuels: Less volatile (prone to evaporate) than spark-ignition fuels but more easily auto-ignited (at high pressures and temperatures) Engines Indirect injection Direct injection Droplets evaporate and premix with aire, burn then auto-ignite the rest of the mixture Blows into main chamber and completes combustion Glow Plug Injector Pre-mix chamber

5. Gas Turbine Engines (aircraft and stationary) Annular Combustor is a relatively small component

6. Annular Multistage Combustor Fuel is atomize Premixed and staged to avoid NO x formation Walls are protected from high temperatures by film cooling

7. Liquid Rocket Engines (fuel and oxidizer are liquid) Pressure-fed by high pressure gas Pump-fed by turbo- pumps Mixed by colliding jets to form unstable sheets and break up

8. Simple Droplet Evaporation Model (no combustion yet)

9. Conservation Laws (isolated droplet) r

10. Solution

11. Apply Other Boundary Condition to find constants

12. Particular Solution

13. Non-Dimensionalization W = 1000 Large Flow W = 100 W = 10

15. Fuel Evaporation Rate

16. Droplet Lifetime

17. Example 10.1