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COMBUSTION TA : Donggi Lee PROF. SEUNG WOOK BAEK
DEPARTMENT OF AEROSPACE ENGINEERING, KAIST, IN KOREA ROOM: Building N7-2 #3304 TELEPHONE : 3714 Cellphone : TA : Donggi Lee ROOM: Building N7-2 #1304 TELEPHONE : 5754 Cellphone :
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COMBUSTION ENGINEERING
THE Shvah-Zeldovitch FORMULATION OF EQUATIONS OF MULTI-COMPONENT REACTING GASES ASSUMPTION NEGLECT (A) BODY FORCE (B) THERMAL DIFFUSION (SORET EFFECT) (C) PRESSURE GRADIENT DIFFUSION (D) BULK VISCOSITY (E) RADIATION STEADY FLOW OVERALL CONTINUITY IN MOST OF LOW SPEED COMBUSTION PROBLEMS VISCOUS TERMS ARE NEGLECTED, IF PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
MOMENTUM EQUATION : JUSTIFICATION ONE DIMENSIONAL SPECIES EQUATION CHEMICAL TIME PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
IF v0 IS A CHARACTERISTIC VELOCITY, : CHARACTERISTIC CHEMICAL LENGTH ~ ORDER OF DISTANCE IN WHICH REACTION IS COMPLETED ~ REACTION ZONE THICKNESS (MANY MOLECULAR COLLISIONS ARE NEEDED) INTEGRATE 1D MOMENTUM EQUATION ONCE PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
IN REGION WHERE VISCOUS EFFECTS ARE IMPORTANT : VISCOUS TIME VISCOUS LENGTH : LENGTH IN WHICH TRANSLATIONAL AND RATATIONAL MODES ARE EQUILIBRIATED: ONE OR TWO COLLISIONS ~ MEAN FREE PATH PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
: IN ATMOSPHERE DIMENSIONLESS VARIABLES PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
WHY BECAUSE CONTINUITY MOMENTUM PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
If : MASS PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
STEADY STATE ENERGY EQUATION NEGLECT KINETIC ENERGY VISCOUS WORK BODY FORCE RADIATION (1) = SPECIFIC INTERNAL ENERGY = HEAT FLUX = (2) PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
SUBSTITUTE INTO PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
ENERGY EQUATION BECOMES (3) (4) SPECIES CONSERVATION, (5) PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
PUT (5) IN (4), (6) PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
(6) SECOND TERM IN (6), USE (7) (8) USE (9) PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
COMBINE (8) & (9) THEN (6) BECOMES, (10) PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
ASSUME THEN (11) RETURN TO SPECIES, COMBINE EQUATIONS (5) & (7) (12) REMARKS : Shvah-Zeldovitch FORM OF EQUATIONS. Cp’s & Cpi’s ARE NOT NECESSARILY CONSTANT. PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
SINGLE REACTION STEP LAW OF MASS ACTION THE RATE OF PRODUCTION OF A CHEMICAL SPECIES IS PROPORTIONAL TO THE PRODUCTS OF THE CONCENTRATION OF EACH REACTANT WITH EACH CONCENTRATION RAISED TO A POWER EQUAL TO ITS STOICHIOMETRIC COEFFICIENT. = CONCENTRATION OF SPECIES i = MOLES PER UNIT VOLUME PER SECOND FORMED OF SPECIES i PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
ALSO WE CAN WRITE, k = SPECIFIC REACTION RATE CONSTANT PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
= RATE OF PRODUCTION FOR ANY SPECIES (MOLES/UNIT VOLUME/S) = MOLECULAR WEIGHT OF SPECIES i PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
FOR SPECIES AND ENERGY EQUATIONS WITH SINGLE REACTION, EACH CAN BE REDUCED TO THE FORM FOR ENERGY EQUATION FOR SPECIES EQUATION PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
L : A LINEAR OPERATOR : NON LINEAR: INVOLVES PRODUCTS OF ‘S OFTEN : ARRHENIUS TYPE SINCE REMARKS ) MAY BE IMPLICITLY NON-LINEAR BECAUSE OF DEPENDENCE OF ON PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
DIFFUSION FLAME ANY FLAME IN WHICH FUEL AND OXIDIZER ARE ORIGINALLY UNMIXED EXAMPLES) CANDLE FLAME PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
DROPLET BURNING INDIVIDUAL DROPLET BURNING OXIDIZER PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
BOUNDARY LAYER ADJACENT TO FUEL SURFACE OXIDIZER FUEL OXIDIZER PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
JET FLAME PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
LAMINAR DIFFUSION FLAMES ARE CHARACTERIZED BY REACTION RATES FAST COMPARED TO RATES OF MASS AND ENERGY TRANSFERS BY DIFFUSION AND CONVECTION REACTION TENDS TO BE CONCENTRATED IN THIN FRONTS WHERE FUEL AND OXIDIZER ARE IN STOICHIOMETRIC PROPORTION. RATE OF CONVERSION OF MIXTURE IS SLOWER THAN THAT IN PREMIXED FLAME PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
(4) WHEN JET VELOCITY EXCEEDS A CERTAIN VALUE THE FLAME BECOMES TURBULENT FLAME HEIGHT JET VELOCITY Hottel and Hawtherns 3RD SYMPOSIUM ON COMBUSTION (1949) LARMINAR TRANSITION TURBULENT PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
QUALITATIVE ANALYSIS L r d V0 OXIDIZER RELATION BETWEEN FLAME HEIGHT L TUBE DIAMETER d FUEL VELOCITY V0 (OR FLOW RATE ) MASS FLOW ~ RATE AT WHICH FUEL AND OXIDIZER MIX BY DIFFUSION PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
FOR GIVEN FUEL D INDEPENDENT OF FOR TURBULENT FLOW REPLACE D BY A TURBULENT DIFFUSION COEFFICIENT, PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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COMBUSTION ENGINEERING
Dt (TURBULENT SCALE)(TURBULENT INTENSITY) SIZE OF LARGEST EDDY L INDEPENDENT OF JET VELOCITY PROPULSION AND COMBUSTION LABORATORY COMBUSTION ENGINEERING
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