Turbo chargers extract energy from the exhaust stream by lowering its pressure as it expands though the turbine. Known as an impulse turbine . This has the undesirable side-effect of increasing the back-pressure in the engine, which decreases scavenging of the exhaust gas from the cylinders and thereby lowers the efficiency of the piston portion.

Design and Function of a Turbocharger - Turbine | BorgWarner Turbo Systems

Turbo compound engines, on the other hand, operate on the "blow down" principle, which extract energy only from the momentum of the rapidly moving exhaust gasses. Although less efficient than the impulse turbine, it has the benefit of not effecting the operation of the piston side of the system, since there is little to no back pressure.

www.dtic.mil/dtic/tr/fulltext/u2/b807167.pdf‎

In summary, the turbocharger is a pressure turbine, a power recovery turbine is a velocity one.

Velocity is transformed across the turbine blade as in a wing that produces lift to px. Velocity is increased in the turbo scoll (divergent duct) from the exhaust. Px in the exhaust pipe from valve to the scoll is not relevant as it velocity that is required and not px.


A compound charger is the same transform's across the blade but instead of driving a compressor it drive a shaft onto the crankshaft.

Cheers

So explain the science behind waste gate operation, does it bleed off velocity or pressure from the system?

This quote from a turbo-charger manufacturer;

So what gives you the px differential across a wing ? Speed / velocity. Velocity across the blade. No difference to any gas turbine. Velocity transformed not px. If it was just px there would be no need for a divergent scroll would there.

Cheers

Remember
Velocity increase. Px decreases temp decrease.

Or

Velocity decreases. Px increases temp increases

Gas law for subsonic flow.

Unless they got that wrong as we'll

Cheers

You are confusing a gas turbine engine with a turbocharger they operate on different principles.

The turbine section of a "jet" engine has stators and rotors, the stators expand the air and accelerate it focusing on the rotors. These are aerofoil shaped and act like a wing turning the shaft.

In the basic turbocharger gas pressure builds up against it and the act of the pressure flowing through the unit to the exhaust drives the shaft.

It's exactly the same the convergent duct in a turbine to increase velocity is the scroll in a turbo. Turbine wheels on a turbo also have airfoils

That's why you can make a jet engine out of a turbo and why anti lag as in a WRC rally car injected fuel into the turbo to increase velocity of the gas flow.

Cheers

A turbine is a divergent duct, not convergent - otherwise known as a nozzle.

Whether it's axial, radial or mixed flow, the principles are the same - expanding gas through a nozzle allows you to capture some kinetic energy that would otherwise be released as heat.

I'm afraid you don't understand the basic principles involved. One operates on the basis of Newtons second law of motion, and the other on the basis of Newtons third law. I'll leave you to figure which might be which.

So the burner can is divergent is it guess better have a closer look. The 1st wheel is the smallest then wheel size increases proportional up to balance size against force as the energy is released
Cheers

no - burner can is (theoretically) the constant pressure part of the brayton cycle.

Bummer can exit is convergent to increase volicity into the I
1st Ngv. From that point onwards it starts to go divergent thought the rest of the engine to get maximum energy recovery. Last point before air enters the bummer can it goes divergent to increase px and slow volicity. Why is this. So you don't blow the flame out
Cheers

Last time I look at a turbo charger ext gas entered the scroll in a convergent duct. Last time I saw a compound disc was approx 8"inches in dia and had on top of it wait for a convergent scroll to once again increase volicity or in your world dose a convergent duct not do that ?
Cheers

And Ngv do several things as the pass the gas flow though the engine. The increase in dia they flow the air onto the next disc at the correct aoa. And they have a convergent duct between the vanes to increase the the volicity of the air passing through the Ngv.

Cheers

Could you please learn to speak english. You posts are completely and totally unintelligible.

Nah they fine if you know what your talking about I just showed the apprentice and he could work it out.
Dia diameter
Aoa angle of attract
Convergent large to small
Divergent small to large
Ngv nozzle guild vane

Cheers

Now that last post made me smile!

:p

He suffers from a very rare affliction known as ABSuRD: Apparently Selective But Random Dyslexia.

He's actually responsible for maintaining aero engines (apparently..), well, those customers who don't have their perfectly maintained burnt valves lying allover the floor that is...

He also suffers from delusions of grandeur