★英語聽力頻道為大家整理的英語六級聽力在線聽：氣泵上的辛烷值是什么意思，供大家參考。更多閱讀請查看本站英語聽力頻道。
氣泵上有兩個辛烷值，87和93。你會選擇哪個？
At the gas pump, you have a choice of octane numbers.87? 93?
這兩個數字有什么不同呢？
What's the difference?
為了解釋辛烷值，讓我們富于想象力的思維先跳躍到汽車的內燃機上面。
To explain octane numbers,let's take an imaginative leap into the internal combustion engine of a car.
氣缸內部是供汽油和空氣的混合物燃燒的內燃室。
Inside the cylinders are combustion chambers where a mixture of gasoline and air burns.
正常情況下，火花塞會點燃這種混合物，爆炸產生的壓力會推下活塞。
辛烷值.jpg
Normally, the spark plug ignites the mixture and the pressure from the resulting explosion pushes the piston down.
但如果燃料和發(fā)動機不匹配，氣缸的熱量在火花塞點火前就會點著燃料。
But, if the fuel is not matched to the engine, the heat in the cylinder can ignitethe fuel even before the spark plug fires.
提前點著燃料會引發(fā)壓力流，使活塞咔噠咔噠作響，發(fā)出爆震音。
This early ignition causes pressure waves that rattle the piston, making a knocking sound.
同時，會使火花塞過熱、燃燒室產生磨損，使得汽車在行駛過程中效率低下并且無法平穩(wěn)運行。
It can also overheat the spark plugs, erode the combustion chamber, and make the car run inefficiently and roughly.
辛烷值也稱為抗爆性指標，表示汽油的抗爆性。
Octane numbers, also known as antiknock ratings, tell you how resistant gasoline is to knocking.
泵里的汽油是經過實驗室檢測的，另兩種參考燃料會在實驗室內與其進行對比。
Gas at the pump has been tested in a lab, where it's compared to two reference fuels.
第一種抗爆性極好，辛烷值達到100。
The first isvery knock resistant, rating 100 on the knock resistance scale.
第二種易產生爆震，辛烷值很低，為零。
The second knocks easily and rates a lowly zero.
我們把兩種燃料混合起來做成用于對比的混合油，
The two are combined to make comparison mixtures.
發(fā)現在試驗過程中，辛烷值為87的汽油和含有87%抗爆劑的混合油效果一樣。
Gas with an octane number of 87, when tested, acted just like the comparison mixturewith 87% knock resistant fuel.
因此，辛烷值越高，抗爆性就越強。
So,the higher the octane number, the more resistant to knocking.
如果發(fā)動機在使用較低辛烷值汽油的情況下不發(fā)生爆震，那就沒有必要在較高辛烷值的汽油上花更多的錢。
If your engine doesn't knock with lower octane gas, there's no reason to spend more on higheroctane.
因為爆震現象部分取決于發(fā)動機的壓縮比，一些發(fā)動機會需要較高辛烷來防止爆震。
Because knocking depends partly on the engine's compression ratio, some engines need higher octanes to prevent it.
車主的實用手冊上通常會寫明適合發(fā)動機的辛烷，而你的耳朵同樣也是檢測爆震的好工具。
Owner's manuals often specify the right octane for your engine, andyour ears are a good measure, too!
氣泵上有兩個辛烷值，87和93。你會選擇哪個？
At the gas pump, you have a choice of octane numbers.87? 93?
這兩個數字有什么不同呢？
What's the difference?
為了解釋辛烷值，讓我們富于想象力的思維先跳躍到汽車的內燃機上面。
To explain octane numbers,let's take an imaginative leap into the internal combustion engine of a car.
氣缸內部是供汽油和空氣的混合物燃燒的內燃室。
Inside the cylinders are combustion chambers where a mixture of gasoline and air burns.
正常情況下，火花塞會點燃這種混合物，爆炸產生的壓力會推下活塞。
辛烷值.jpg
Normally, the spark plug ignites the mixture and the pressure from the resulting explosion pushes the piston down.
但如果燃料和發(fā)動機不匹配，氣缸的熱量在火花塞點火前就會點著燃料。
But, if the fuel is not matched to the engine, the heat in the cylinder can ignitethe fuel even before the spark plug fires.
提前點著燃料會引發(fā)壓力流，使活塞咔噠咔噠作響，發(fā)出爆震音。
This early ignition causes pressure waves that rattle the piston, making a knocking sound.
同時，會使火花塞過熱、燃燒室產生磨損，使得汽車在行駛過程中效率低下并且無法平穩(wěn)運行。
It can also overheat the spark plugs, erode the combustion chamber, and make the car run inefficiently and roughly.
辛烷值也稱為抗爆性指標，表示汽油的抗爆性。
Octane numbers, also known as antiknock ratings, tell you how resistant gasoline is to knocking.
泵里的汽油是經過實驗室檢測的，另兩種參考燃料會在實驗室內與其進行對比。
Gas at the pump has been tested in a lab, where it's compared to two reference fuels.
第一種抗爆性極好，辛烷值達到100。
The first isvery knock resistant, rating 100 on the knock resistance scale.
第二種易產生爆震，辛烷值很低，為零。
The second knocks easily and rates a lowly zero.
我們把兩種燃料混合起來做成用于對比的混合油，
The two are combined to make comparison mixtures.
發(fā)現在試驗過程中，辛烷值為87的汽油和含有87%抗爆劑的混合油效果一樣。
Gas with an octane number of 87, when tested, acted just like the comparison mixturewith 87% knock resistant fuel.
因此，辛烷值越高，抗爆性就越強。
So,the higher the octane number, the more resistant to knocking.
如果發(fā)動機在使用較低辛烷值汽油的情況下不發(fā)生爆震，那就沒有必要在較高辛烷值的汽油上花更多的錢。
If your engine doesn't knock with lower octane gas, there's no reason to spend more on higheroctane.
因為爆震現象部分取決于發(fā)動機的壓縮比，一些發(fā)動機會需要較高辛烷來防止爆震。
Because knocking depends partly on the engine's compression ratio, some engines need higher octanes to prevent it.
車主的實用手冊上通常會寫明適合發(fā)動機的辛烷，而你的耳朵同樣也是檢測爆震的好工具。
Owner's manuals often specify the right octane for your engine, andyour ears are a good measure, too!