Generation and Control of Turbulent Flames in SI Engine

Slides:



Advertisements
Similar presentations
MAE 5310: COMBUSTION FUNDAMENTALS
Advertisements

Turbulent Combustion Jehad Yamin.
STUDENT NAME: (1) Patel Vidhi A.
Combustion Chamber Design
Conceptual & Thermodynamic Description of Expansion in I.C. Engine P M V Subbarao Professor Mechanical Engineering Department The Actual & Useful Extent.
Effect of Piston Dwell on Engine Performance P M V Subbarao Professor Mechanical Engineering Department Sufficiency of time to Execute a Process…..
Selection of Rod Ratio for I.C. Engines
Four Stroke Cycle Engine
Performance of Ignition Process P M V Subbarao Professor Mechanical Engineering Department Effectiveness of Ignition for Efficient Combustion …..
LES Combustion Modeling for Diesel Engine Simulations Bing Hu Professor Christopher J. Rutland Sponsors: DOE, Caterpillar.
Kinematic Analysis for A Conventional I.C. Engine P M V Subbarao Professor Mechanical Engineering Department Creation of Instantaneous Volume, Surface.
Design of Intake Systems for better in-cylinder Turbulent Flow
AE 412 THERMODYNAMIC CYCLE SIMULATION II Prof.Dr. Demir Bayka.
I.C. ENGINES LECTURE NO: 13 (28 Apr 2014).
Control of Heat Release Rate in S.I. Engines P M V Subbarao Professor Mechanical Engineering Department Development of Models to Design & Select Hardware…...
Analysis of In-Cylinder Process in Diesel Engines P M V Subbarao Professor Mechanical Engineering Department Sudden Creation of Young Flame & Gradual.
Design Framework for Turbo Combustor P M V Subbarao Professor Mechanical Engineering Department Design for performance, safety and Reliability…..
Transport Equations for Turbulent Quantities
Strategies to Achieve A Fast Cycle with High & Safe Peak Pressure in SI Engines P M V Subbarao Professor Mechanical Engineering Department Fuel Economy.
Influence of Design & Operational Parameters on Volumetric Efficiency of Engine P M V Subbarao Professor Mechanical Engineering Department Clues to Improve.
Selection of Geometric Ratios for I.C. Engines P M V Subbarao Professor Mechanical Engineering Department Control of Micro Actions through Macro Features…..
Maximization of Flow through Intake & Exhaust Systems
Design & Thermo Chemistry of Turbo Combustor P M V Subbarao Professor Mechanical Engineering Department Design for performance, safety and Reliability…..
Nature of Heat Release Rate in an Engine
Design & Analysis of Combustion System for Diesel Engines P M V Subbarao Professor Mechanical Engineering Department Means & Methods to Promote Matured.
Design of Engine Cylinder for Creation of A Selected Turbulent Flow P M V Subbarao Professor Mechanical Engineering Department Geometry to create qualitatively.
Strategies for Complete Expansion in I.C. Engine P M V Subbarao Professor Mechanical Engineering Department Achieve Maximum Work Output….
Development of Thermodynamic Models for Engine Design P M V Subbarao Professor Mechanical Engineering Department Methods to Design for Performance….
Auto Ignition, Premixed & Diffusive Combustion in CI Engines
Compression Ignition Engines
Volumetric Efficiency of Engine P M V Subbarao Professor Mechanical Engineering Department Quantification of Filling & Emptying Effectiveness….
Phenomenological Modeling of Internal Combustion Engines P M V Subbarao Professor Mechanical Engineering Department A method of inquiry based on the premise.
The Chemistry of Fuel Combustion in SI Engines P M V Subbarao Professor Mechanical Engineering Department Exploit the Chemical Characteristics of Combustion?!?!
1 Four Stroke Engines How does a canon work?. 2 Engine Operation Gasoline & diesel engines convert chemical energy into mechanical energy.
Geometry Vs Engine Breathing P M V Subbarao Professor Mechanical Engineering Department Its not engine Volume, but Mass of air Decides the Power Output.
Combustion in SI Engines P M V Subbarao Professor Mechanical Engineering Department A n Effect due to Complex Fluid Dynamic & Thermo-chemical ActivitiesS…
Wave Action Theory for Turning of Intake & Exhaust Manifold
Design of Engine Valves An Extended /Applied Fluid Mechanics…. P M V Subbarao Professor Mechanical Engineering Department.
Combustion in Diesel Engines P M V Subbarao Professor Mechanical Engineering Department Special Behavioral Issues of Teen Combustion ….
Transient Processes in Internal Combustion Engines P M V Subbarao Professor Mechanical Engineering Department Recognize the Role and Importance of Time.
TYPES OF COMBUSTION CHAMBERS - CI Engines
Cumbustion Chamber Manish K.MISTRY [ ]
Thermodynamics, Lesson 4-4: The Air Standard Diesel Cycle
COMBUSTION FUNDAMENTALS Turbulent Premixed and Non-Premixed Flames
Analysis of Port Injection Systems for SI Engines
Analysis of GDI Internal Combustion Engines as Automobile Prime Movers
Introduction to the Turbulence Models
MAE 5310: COMBUSTION FUNDAMENTALS
Unit - 2 INTERNAL COMBUSTION ENGINES.
Introduction to Symmetry Analysis
SPARK IGNITION ENGINES
Strategies for Complete Expansion in I.C. Engine
Enhanced Activities due to In Cylinder Turbulence
Next Generation SI Engines : GDI Internal Combustion Engines
MSU Rapid Compression Machine and Turbulent Jet Ignition Testing
Development of Design Knowledge for GDI Internal Combustion Engines
P M V Subbarao Professor Mechanical Engineering Department
Estimation of Turbulent Flame Speeds in SI Engines
Fuel-Air Modeling of IC Engine Cycles
P M V Subbarao Professor Mechanical Engineering Department
Flame Propagation in SI Engine After intake the fuel-air mixture is compressed and then ignited by a spark plug just before the piston reaches top center.
C H A P T E R 15 Thermodynamics
Basic Principles for Design of Ignition Systems
COMBUSTION TA : Donggi Lee PROF. SEUNG WOOK BAEK
CIET,LAM,DEPARTMENT OF MECHANICAL ENGINEERING
Turbulent Diffusive Combustion in CI-DI I C Engines
IC Engines Classifications
The airplane engine packet
Design rules to generate Turbulent Flame Speeds in SI Engines
Analysis of Turbulent Flame in SI Engine
Presentation transcript:

Generation and Control of Turbulent Flames in SI Engine P M V Subbarao Professor Mechanical Engineering Department Safe, Reliable and Fast Combustion needs the Help of Turbulence….

A Three Step Approach to Control Flame Speed in SI Engines In a Homogeneous mixture of fuel and air Study & Control of Planar (constant Area) Laminar Flames. Control of Non-planar (variable area) Laminar Flames. Control of Turbulent Flames

Description of Turbulent Flow in An Engine Cylinder

Phases of the Flow inside an Engine Cylinder The flow in the cylinder can be divided into several distinct phases: The flow of air-fuel mixture into the cylinder through the intake valve or valves as a turbulent jet. Decaying turbulent in-cylinder flow during (the later part of) the intake stroke. Growing turbulent flow during the compression stroke. Amplification of turbulence level due to combustion. Flow with a strong attenuation of the turbulence during expansion stroke.

Instantaneous Local Velocity in an I.C. Engine Cylinder : A Sketch

Evidence of Organized Vortical Structure in an Engine 1200 rpm motored engine Instantaneous Velocity Distribution In Mid Plane During Cycle 1 Instantaneous Velocity Distribution In Mid Plane During Cycle 20 90 Cycle Mean Velocity Distribution In Mid- Plane

Turbulent Energy Spectrum The turbulent incylinder flow consist in many eddies of varying sizes and orbital speeds, d and uO. Each of these may not be a of a single value but vary within a certain range.

Vortical Description of In-Cylinder Flow The size of most energetic eddy is found to be roughly B/6 , where B is the bore. A general engine flow, at middle third of the intake stroke has an tangential velocity of roughly 10 ×Sp , where Sp ,is the average piston speed. This means that this vortex has cycle time of (a time scale) of roughly, B/ 60 ×Sp . What is the use of this knowledge?

Energetic Characterization of Turbulent Flow The largest eddy at TDC will be roughly the clearance height, while at BDC it will be roughly the cylinder bore The largest eddies are relatively weak. The kinetic energy of the eddies varies with size or scale. As the size drops, the energy initially rises rapidly to a peak, and then falls continually down to the smallest eddies. The most energetic eddy, at the peak, which is responsible for most of the transport, is about 1/6 the size of the largest eddy ‐ thus, 1/6 of the bore at BDC, or 1/6 of the clearance height at BDC.

Fast Vortex Flow Faster than the Average Piston Velocity The most energetic vortex completes a cycle @ 60 times faster than intake stroke of piston. How to use of this knowledge? It tells us that this vortex can mix the gas 60 times during an intake stroke, if it is alive throughout the stroke.

Size of the Largest Eddy The span of length scales in a turbulent flow is related to its Reynolds number. Indeed, in terms of the largest velocity scale, which is the orbital velocity of the largest eddies, UO= uO(dmax). The energy supply/dissipation rate equation is: L is a general symbol for dmax.

Clues to Develop a Healthy Turbulent Flow in An Engine Cylinder Eddy turnover time: Characteristic Chemical Reaction Time: The ratio of the characteristic eddy time to the laminar burning time is called the Damkohler Number Da.

Span of Multi-scale Turbulent Flames Multi-scale turbulent flames are essential for operation of high speed engines. Turbulent flames are characterized by rms velocity fluctuation, the turbulence intensity, and the length scales of turbulent flow ahead of flame. The Largest scale, L is also called as an integral length scale. The smallest length scale is known as Kolmogrov scale . The span of eddy scales:

Identification of A Control(Dimensionless) Parameter Turbulent Reynolds Number: Important controlling dimensionless parameter: