Ch.12 Turbulent Prem.. - Propulsion and Combustion Laboratory
Ch.12 Turbulent Prem.. - Propulsion and Combustion Laboratory
Ch.12 Turbulent Prem.. - Propulsion and Combustion Laboratory
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Combustion</strong>, Autumn 2004Chapter 12<strong>Turbulent</strong> <strong>Prem</strong>ixed FlamesMan Y. Y. Kim<strong>Propulsion</strong> <strong>and</strong> <strong>and</strong> <strong>Combustion</strong> Lab.PROFESSORDepartment Department of of Aerospace Aerospace Engineering, Engineering, Chonbuk ChonbukNational University UniversityChonbuk Chonbuk561-756ROOM ROOM ## 3215, 3215, T.2473, T.2473, manykim@chonbuk.ac.kr
Some Applications• spark-ignition engines• gas-turbine engines• industrial gas burners12-2 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Spark-Ignition Engines 112-3 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Spark-Ignition Engines 212-4 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Definition of <strong>Turbulent</strong> Flame Speed• Example 12.1• <strong>Turbulent</strong> Flame SpeedmSt= Aρuwhere ⎧ m= reactant flow rate⎪⎨ ρu= unburned gas density⎪⎩ A = time - smoothed flame area12-5 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Structure of <strong>Turbulent</strong> <strong>Prem</strong>ixed Flames 1‣ Experimental Observations• turbulent flame brush• laminar flamelet12-6 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Structure of <strong>Turbulent</strong> <strong>Prem</strong>ixed Flames 2‣ Three Flame Regions• wrinkled laminar-flame regime : δL≤l• flamelets-in-eddies regime : l > δ > l• distributed-reaction regime : δ >lwhere,⎧⎨⎩llK0K0 L K: Kolmogorov microscale: integral scale‣ Damkohler Numbercharacteristic flow time τDa ≡ =characteristic chemical time τl v′ ⎛ l ⎞⎛ S ⎞here,0 rms 0 L= = ⎜ ⎟⎜ ⎟δL SL δL v′rms⎧⎪⎨⎪⎩Da 1Da 1⎝ ⎠⎝ ⎠: fast chemistry regime(mixing-controlled)L0flowchem: kinetics-controlled regime12-7 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Example 12.212-8 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Wrinkled Laminar-Flame Regime12-9 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Distributed-Reaction Regime12-10 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Flamelets-in-Eddies Regime12-11 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Flame Stabilization• low-velocity bypass ports• refractory burner tiles• bluff-body flameholders• swirl or jet-induced recirculating flows• rapid increase in flow area creating recirculating separated flow12-12 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.
Homework Overview # 9(1) Solve the problem 12.3, 12.6 <strong>and</strong> 12.712-13 <strong>Propulsion</strong> <strong>and</strong> <strong>Combustion</strong> Lab.aerospace.chonbuk.ac.kr
Change language