Diffuser
 

Hello everyone ;
actually i want to build my own jet engine,i have compressor impller and i am trying to design the other parts.
in designing diffuser i have some questions.
this is my first questions:
which one is better for micro turine?fisrt or sec...............
which type of diffuser:1 wedges shaped or2 vaned???
TNX

SECOND FOR SURE . LIGHTER. SECOND. EXIT NEEDS TO BE, LARGER CROSS SECTION, TO SLOW AIR FROM COMP. WHEEL..{ Diffuser }

The first is more efficient due to more constant air flow after the compressor!

Its a,, deffuser,, not ducting,,need to slow air down before 90.deg turn flow straiteners. Need exspantion of area to slow air down. Air of comp. Tips is way to fast.. No pressure.

Neither is the best. The second type can be radically improved by doing 2 things.
1.Where the airflow turns the cross section area should be "pinched" otherwise boundary layer growth will choke the diffusor.
2. Fit a splitter vane for the last half of the channel. It should be slightly closer to the suction side of the vane next to it.

Like I said the first picture shows no need for additional splitters and is far easier to manufacture as in most commercial micro turbines on the market today!

2-2-2-2 no vane

TNX John and Moerig for answers.
Moerig can you more explain about this two ways ?

Compressors need to be compact because of rpm limits. So they have to use splitters to limit boundary layer growth.
The diffuser needs splitters because model size engines have too little room for single channel ducts.
This has been proven in professional applications where 10% more thrust and 5% less fuel burn was achieved.
The Wedge diffuser is OK but the 90 deg bend causes massive flow breakaway and as a result the air accelerates into the engine.
It can be so bad that removing the diffuser can have same result in performance.
So at the bend we need to accelerate the air so that we reduce the breakaway.
Its the lesser of 2 evils.
We accelerate air by reducing the height of the channel at the bend.
This is result of 10 years of work with Supercomputer and CFD.