Diesel Engineer - Flame Front

[TBow]

Hello there, looking to settle a discussion amoung friends. Looking for an answer to: "Is there a flame front in a diesel engine when flame propagation occurs?"

 

[mattsooty]

Yes and no.

The first portion of the burn is similar to a flame front as those portions of the charge that are in a combustible state are consumed.

Thereafter that the combustion occurs by way of a diffusion flame whereby pockets of charge autoignite.

MS

 

[DanishDiesel]

HELLO! THIS IS THE MY FIRST WRITING ON ENG-TIPS.

WHEN THE PISTON REACHES TDC, THE COMPRESSION IN THE CHAMBER IS HIGH AND THE NOZZLE STARTS TO BLOW DIESEL INTO THE CHAMBER. THE FIRST DIESEL THAT GETS INTO THE HOT AIR EVENTUALLY IGNITES AND CAUSES A BURNING OG THE DIESEL, BUT THE IGNITION OCCURS WERRY FAST AFTER THE START OF THE SPRAY, SO - THE REST OF THE DIESEL IS SPRAYED INTO THE BURNING DIESEL, AND THE REST OG THE DIESEL IS BURNING. tHE FIRST DIESEL IS IGNITING, AND THE REST IS BURNING. THE SURFACE OF THE DIESEL SPRAYED INTO THE COMBUSTIONCHAMBER, IS IMPORTANT, A BIG SURFACE GIVES FASTER IGNITION, THAN A LOW SURFCE. WHEN YOU INCREASE THE PRESSURE ON THE NOZZLE, THE SPRAY WIL CONTAIN SMALER DROPS, HENCE MORE DROPS, SINCE THE WOLUME OF DIESEL IS THE SAME, BUT AT LOT OF SMALL DROPS HAS BIGGER SURFACE AREA THAN A FEW LARGE ONES. WHEN AN ENGINE I NEW,THE NOZZLES GIVES A FINE SPRAY, SO IGNITION WIL OCCUR FAST, BECAUSE OF THE BIG AREA OF THE DIESEL. WHEN THE NOZZLE STARTS TO SPRAY INTO THE CHAMBER THE IGNITION WILL OCCUR FAST, MEANING THAT ONLY AT LITTLE AMOUNT OF DIESEL WILL BEE RIQUIRED TO START AN IGNITION, AND THE REST OF THE DIESEL, WHICH IN A NEW ENGINE WILL BE THE MOST, WILL BE SPRAYED INTO THE BURNING DIESEL. AS THE ENGINE BECOMES WORN, PRESSURE WIL FAL AND THE DROPS WIL BECOME LARGER. THES DROPS TAKES LONGER TO HEAT UP AND IGNITE. IT IS THE FIRST PART, THE IGNITION OF THE DIESEL, WICH MAKES THE PING(KNOCK) IN THE ENGINE, THE REST OF THE DIESEL DOES NOT IGNITE IS BURNS AND MAKES ONLY A SMALL SOND. IN THE WORN ENGINE, THE DIESELDROPS ARE MUCH BIGGER, SO WHEN THE ENGINE STARTS TO SPRAY DIESEL INTO THE CHAMBER, IT TAKES AT LONG TIME FOR THE DIESEL TO HEAT UP ENOUGH TO IGNITE. SO THEN IT TAKES LONGER FOR THE DIESEL TO IGNITE, IT ALSO MEANS THAT THE NOZZLE GETS TIME TO SPRAY A LOT MORE DIESEL INTO THE CHAMBER BEFORE IGNITION, SO NOW WE HAVE AN CHAMBER WITH AT LOT OF DIESEL IGNITING, IN STEAD OF BURNING, AND YOU WIL HAVE A WERY BIG KNOCKING ENGINE. IT IS THE FIRST DIESEL, THAT IGNITES WICH MAKES THE KNOCKING, SO IN ORDER TO MAKE THE KNOCK AS SMALL AS POSSIBLE, MODERN NOZZLE, HAVE TWO STAGES INSTED OF ONE. THE FIST PRESPRAY, IS WERY LITTLE AND COMES A LITTLE TIME BEFORE THE MAIN SPRAY. THIS WERY LITTLE MIST HEATS UP AND IGNITES, AND MAKE ONLY A WERY LITTLE PING. NOW THE CONTENT OF THE CHAMBER IS BURNING, AND THE REST OF THE DIESEL IS SPRAYED INTO THIS BURNIG DIESEL AND MAKES A WERY GOOD AND QUIET BURNING OF THE DIESEL.

 

[Fabrico]

Good job Danish.
It's always a good idea to use normal lower case lettering and do some proof-reading before submitting a post.

 

[tbuelna]

There is only combustion where there is sufficient oxygen, fuel and heat.