Auto Tech Part 1

A large We number indicates that the deforming aerodynamic forces are much larger than the reforming surface tension forces.

What do the terms dng and sg represent in the log-normal distribution?

What is the acronym SMD stand for?

SMD describes the "average" diameter of an ensemble of droplets by weighting the average by both the surface area and the volume.

Why is SMD used to characterize droplet size?

What is the We number?

The log normal distribution for droplet size is given by this equation.

What is one key advantage of the log-normal distribution?

What are some dropsizing techniques?

The log normal distribution is used because it has been found experimentally to be a good fit for sprays.

What are some of the disadvantages of using PDV as a dropsizing technique?

I want to measure a dense spray. Which drop-sizing technique should I use?

A "hollow core" or "air core" is formed by the swirl of the liquid.The tangential velocity of the outgoing liquid is given by two equations, relating the mass of liquid, the port area, and the chamber radius. At a radial position of r=0, the tangential velocity is equal to infinity. As this is impossible, a low pressure or vapor core is observed.

The process that govern CO formation are .....

In the premixed flame, the CO concentration.....

The Zeldovich mechanism is the mechanism that describes the formation of NO by breaking down O2 to O atoms and N2 to N atoms. The subsequent reactions produce NO.

What are some mechanisms of HC formation?

Combustion behavior is substantially controlled by the AFR. What is this?

How is No emissions mainly formed?

What are the pollutant emissions produced by a conventional gasoline engine?

The reactions to produce NO are very sensitive to temperature because the production of O atoms is essentially exponential with temperature.

How can the production of NOx be controlled or reduced?

What are some of the requirements for using catalytic abatement to reduce NOx?

In order to reduce the production of NO, a lean burn operation is used. This requires a specifically designed engine where a port fuel injector is made through an open inlet valve.

Increasing the AFR can significantly reduce the formation of CO and HC.

Ignition delay period (or time) is the delay time between the start of injection and the start of combustion in a Diesel engine. What determines the delay time?

What happens when there is a long ignition delay period?

The three distinct phases of combustion for a diesel engine are premixed combustion, mixing controlled combustion, and end-phase combustion.

Which phase of the combustion process in a diesel engine produces the most NO?

During which phase of combustion in a diesel engine is most of the soot formed?

What is the break up time of spray?

Advanced diesel combustion combines split injection strategies with catalytic abatement.

What is the prime parameter in determining the quantities of NOx formed in a traditional gasoline engine?

A "split injection" system allows the rich zone of the fuel to be significantly reduced whilst maintaining flexibility with engine load (eg the amount of fuel injected) .

How does a split injection system (single pulse) help reduce smoke production?

How does using EGR help with diesel combustion?

What are some benefits of using high pressure injection in a DI Diesel Engine?

A DIG achieves a lean burn by manipulating a rich region to the spark plug by controlling the timing and form of injection in conjunction with the in-cylinder air flow.

How does lean burn increase bfsc?

The cone angle is defined as the angle between two straight lines originating from the orifice exit of the nozzle and being tangent to the spray outline. This angle usually ranges from 5 to 30 degrees.

Fuel spray tip penetration is defined as the maximal distance measured from the injector to the spray tip. It represents the maximum penetration length achieved by the droplets in the center of the spray.

How is the cone angle mainly affected?