Chapter 6 & 7

2

- Most pistons have __ or more compression rings.

High

- turbulence in a cylinder is ____ during intake

Thermodynamic transfer rates

As a result of turbulence, ______ within an engine are increased by an order of magnitude.

80%

Clearance between the piston and the cylinder walls is ¬___ of the total crevice volume.

Tuning effect

Constructive or destructive interference resulting from two or more reflectors spaced closer than a quarter of the dominant wavelength.

Turbulent flows

Due to the high velocities involved, all flows into, out of, and within engine cylinders are ______.

Ignition delay

Not totally changed by the increase in turbulence is _______.

1

Pistons have at least __ oil ring.

Homogeneous

Swirl makes turbulence more _____ throughout the cylinder.

Combustion

The high turbulence near TDC when ignition occurs is very desirable for _____.

Roughened

The inside surfaces of these manifolds are ____to promote higher turbulence levels to enhance evaporation and air-fuel mixing.

True

The shape of the combustion chamber is extremely important in generating maximum turbulence

Intake pressure

The total pressure taken in the engine inlet as a measure of air density.

True

There are many levels of turbulence within an engine

Expansion

This turbulence is enhanced by the _____ of the cylinder gases during the combustion process.

Volumetric efficiency

To maximize ____, the inside surface of most intake manifolds is made as smooth as possible.

1-3%

Total crevice volume is only _____ of the total clearance volume

Engine speed

Turbulence intensity is a strong function of ______.

Scavenging

Turbulence is detrimental in the ____ process of a two-stroke cycle engine.

Random fluctuations

When flows are turbulent, particles experience _____ in motion superimposed in their main bulk velocity

5%

____ of the clearance volume came from the Imperfect fit in the threads of spark plug or fuel injector.

10-15%

______ of the crevice volume came from the gaps in the gasket between head and block.

Statistical averaging

_______ over many engine cycles gives accurate average flow conditions.

Valve

a device for controlling the flow of fluids in a pipe or some other enclosure.

Combustion

a process in which a substance reacts with oxygen to give heat and light

Fuel Injector

a pump and valve mechanism that sprays liquid fuel intermittently into the cylinder of a diesel engine.

Moment of Inertia

a quantity expressing a body's tendency to resist angular acceleration.

Automobiles

a road vehicle, typically with four wheels, powered by an internal combustion engine or electric motor.

Engine knock

a situation where in fuel burns unevenly and shocks go off at the wrong time.

Poppet valve

a valve typically used to control the timing and quantity of gas or vapor flow into an engine.

Crevices

are narrow regions in which fuel air mixture can flow.

Ports

are passages that allow fluid to pass through the valve.

Reversed squish

as the piston moves away the TDC, the burning gases are propelled radially outward.

Viscous dissipation

controls the smallest scale turbulence

Bore

diameter of rotating mass

Convection

high turbulence enhances the _____ heat transfer to the walls in the combustion chamber.

Oil sump

is a component of the engine lubrication system in motor vehicles. It is also known as the oil tray.

Mathematical model

is a description of a system using mathematical concepts and language

Paddle wheel

is a device for converting between rotary motion of a shaft and linear motion of a fluid.

Spark Plug

is a device in the engine of a vehicle which produces electric sparks to make the gasoline burn.

Heat exchanger

is a device used to transfer heat between a solid object and a fluid, or between two or more fluids.

Swirl ratio

is a dimensionless parameter used to quantify rotational motion within the cylinder.

Thermal efficiency

is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, furnace, or a refrigerator for example.

Inert gas

is a gas which does not undergo chemical reactions under a set of given conditions.

Combustion efficiency

is a measurement of how well the fuel being burned is being utilized in the combustion process.

Tumble

is a secondary rotational flow caused by squish.

Orifice

is a small opening provided on the side or bottom of a tank, through which a fluid is flowing.

Lean mixture

is an air-fuel mixture containing a relatively low proportion of fuel.

Rich mixture

is an air-fuel mixture containing an excessive proportion of fuel.

Exhaust gas recirculation (EGR)

is an effective strategy to control NOx emissions from diesel engines.

Simulation

is an imitation of the operation of a real-world process or system.

Mass flow of EGR

is defined as the mass flow of EGR divided by the mass flows of EGR

Oil ring

is for lubrication and offers no resistance to gas leakage.

Combustion chamber

is that part of an internal combustion engine (ICE) in which the fuel/air mixture is burned.

Crank angle of Ignition

is the angle that the crankshaft makes where ignition starts

Piston ring gap

is the distance between ends of the ring when installed in cylinder

Valve Lift

is the distance by which the valve is raised from its seated position when it is fully opened.

Exhaust gas

is the gas emitted as a result of combustion.

Blowby

is the gas that gets totally past the piston and ends up in the crankcase

Crankcase

is the housing for the crankshaft in a reciprocating internal combustion engine.

Rocker ratio

is the length of the valve side of the rocker arm to the center (or pivot point) of the rocker arm divided by the length of the Cam or Pushrod side to the center of the rocker arm.

Cylinder gas mixture

is the mixture of gases in the cylinder of an internal combustion engine.

Heat transfer

is the movement of thermal energy from one thing to another thing of different temperature

Heat Transfer

is the movement of thermal energy from one thing to another thing of different temperature.

Piston

is the moving component that is contained by a cylinder and is made gas-tight by piston rings.

Intake manifold

is the part of an engine that supplies the air/fuel mixture to the cylinders.

Squish

is the radial inward motion of the gas mixture

Computer simulation

is the reproduction of the behavior of a system using a computer to simulate the outcomes of a mathematical model associated with said system.

Engine speed

is the rotational speed of an engine in terms of revolutions per minute.

Valve seat

is the surface against which an intake or an exhaust valve rests during the portion of the engine operating cycle when that valve is closed.

Cylinder head

it sits above the cylinders on top of the cylinder block.

Fuel

material such as coal, gas, or oil that is burned to produce heat or power.

Large-scale turbulence

occurs with eddies on the order of the size of the flow passage

Cylinder head porting

process of modifying the intake and exhaust ports of an ICE to improve quality and quantity of air flow.

Combustion

rapid chemical combination of a substance with oxygen, involving the production of heat and light.

Viscous drag

reduces swirl ratio quickly during compression stroke.

Piston pin offset

refers to the piston wrist pin being a bit offset to one side of the piston for it to not be in the center of the piston.

Crank angle

refers to the position of an engine's crankshaft in relation to the piston as it travels inside of the cylinder wall, measured in degrees.

Compression rings

seal the clearance gap between the piston and cylinder walls

Torodial

simple bowl showing squish action.

Burn angle

the crank angle through which the engine turns as combustion takes place.

Residual gases

the gases that remain in the cylinder of an internal-combustion engine after the exhaust stroke has been completed.

10 degrees before TDC

the maximum squish velocity usually occurs.

Intake

the opening through which fluid enters a duct or channel.

Combustion

the process of burning

Ignition

the process of igniting the fuel in an internal-combustion engine

Emission

the production and discharge of something, especially gas or radiation

Emission

the production and discharge of something, especially gas or radiation.

Volumetric efficiency

the ratio of the volume of fluid actually displaced by a piston or plunger to its swept volume.

Swirl

the rotational motion of a fluid mass within the cylinder

True

the smallest scale turbulence is totally random and homogeneous

Flame propagation

the spread of a flame in a combustible environment outward from the point at which the combustion started

Chemical kinetics

the study of rates of chemical processes

Flame front

the surface of the interface that faces reactants.

Cylinder wall temperature

the temperature of the cylinder wall of an internal combustion engine.

Clearance Volume

the volume between the cylinder head and the piston top when the piston is at top dead center.

Reverse blowby

when the exhaust valve opens, pressure between the compression rings will be greater than in the combustion chamber, and some gases will be forced back into the chamber.

Intake process

where the swirl ratio is high.

Motoring

without giving the fuel or ignition just run the engine with help of motor.