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Do you guys know something about axial turbochargers being tested on car engines?

This is a quite obscure topic. I could only find references mentioning their massive size (turbo lag) yet with higher efficiency.

Not heard of anyone trying to get one to work on a relatively small road car engine.

From what I know of axial turbochargers they are typically used in large industrial diesel or heavy fuel engines that run at constant RPM's like ship engines or electricity production units on heavy mining machinery. Man Diesel, Cummins, Mitsubishi etc who all built large ship diesels have used/are using them.

As they are much larger (heavier) than the small radial flow chargers they are significantly slower to spin up, they have very poor response characteristics. However once spinning they are very efficient containing multiple "stator" stages to give greater pressures and flow.

For use on a smaller engine like a road car, as they are so slow in transient response times, you would need to keep them spinning so that you always had close to or absolute maximum boost pressure and then regulate the produced pressure flow through bleeding it off prior to the plenum/throttle/manifold. You still have the packaging and efficiency considerations of mounting it up and getting the engine exhaust to drive it without placing a huge parasitic loss on the engine through pumping losses.

What has axial flow instead of conventional radial flow-- the compressor or the exhaust turbine? Or both?

bill shoe wrote:What has axial flow instead of conventional radial flow-- the compressor or the exhaust turbine? Or both?

Both from my understanding, which is why the packaging is usually large and why its used on bigger engines.

the centrifugal/radial flow stuff does a great job of efficiently compressing to any level appropriate to the piston engine, all in a single stage (2014 rules demand single stage)

axial flow stuff works well only as multi-stage (your airliner uses this to get around 20:1 compression)

axial flow is (even) harder to match to varying rpm

recently a turbine guy posted on one of these hot threads (I can't find it right now)

aussiegman wrote:Not heard of anyone trying to get one to work on a relatively small road car engine.

http://turbo.honeywell.com/our-technolo ... ochargers/

noname wrote:

aussiegman wrote:Not heard of anyone trying to get one to work on a relatively small road car engine.

http://turbo.honeywell.com/our-technolo ... ochargers/

Food for thought...thank you.

With the stage pressure ratios and flows required in most automotive turbochargers centrifugal designs are a much better choice than axials. The problem mostly has to do with the way the aerodynamics scale at small sizes. While it would be theoretically possible to make tiny axial flow turbochargers, the higher cost and lower efficiency would be unacceptable.

Modern small/medium turboshaft engines are currently trending toward centrifugals for the high presssure compressor stages, but they still use axial turbine stages due to thermal issues. At high pressures, the centrifugal compressor gives better performance and less leakage losses.

noname wrote:

aussiegman wrote:Not heard of anyone trying to get one to work on a relatively small road car engine.

http://turbo.honeywell.com/our-technolo ... ochargers/

Interesting. Possible a packaging advantage or it they were trying to maintain constant RPM. Would be interesting to compare shaft torque between a radial and axial unit. If they were trying to run a hybrid unit with an electric generator unit.

Basically a radial compressor achieves a higher pressure rise, whereas a axial one has a higher mass flow. For turbo charging a engine pressure is required. A yet engine needs mass flow in first place and achieves the required pressure ratio by using several stages.
Then the leakage over a radial rotor is less because a larger distance is travelled in relation to the short blades of a axial compressor.

mep wrote: ↑

09 Jul 2012, 12:24

Basically a radial compressor achieves a higher pressure rise, whereas a axial one has a higher mass flow. For turbo charging a engine pressure is required. A yet engine needs mass flow in first place and achieves the required pressure ratio by using several stages.
Then the leakage over a radial rotor is less because a larger distance is travelled in relation to the short blades of a axial compressor.

Breathing life into this old corpse of a thread :

What about the turbine side, as with Honeywell's Dual-Boost?