Looking for a Turbocharger with a Shrouded Turbine Wheel?

[Sunfire]

Hi,

could someone suggest a turbocharger model? My lab needs one for demonstration purposes. It needs to have a (radial inflow) turbine wheel up to 6 inch diameter. Has to come with inlet manifold, it'd be nice the inlet manifold to have a set of nozzles/stator vanes.

It'd be perfect if this would be a shrouded turbine wheel.
Off-the-shelf for low price is highly desirable

It has to demonstrate it is able to efficiently extract work from the injected gas.

We already tried with this one. At 10 atm inlet pressure it hardly reached 100,000rpm and thus the compressor's output was weak. Need something better than this for sure! Or putting it on an engine won't make any difference.

Help!

 

[Greg Bernhardt]

I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?

 

[Sunfire]

Hello, thanks for the reply... It turns out the turbocharger for Ford diesel engines (e.g. F-250) is equipped with stator vanes; (image attached); Unsure if smaller turbochargers with vanes exist on the market

Thanks

 

[jack action]

We already tried with this one. At 10 atm inlet pressure it hardly reached 100,000rpm and thus the compressor's output was weak. Need something better than this for sure! Or putting it on an engine won't make any difference.

If I understand correctly, it seems you are saying you've put an inlet pressure of 10 atm at ambient air temperature.

If this is the case, it won't work. For a turbine to work as designed, it needs a certain mass air flow and inlet temperature. Here's an example of such relationship:

Note that the typical expansion ratio of a radial turbine is 2:1 to 3:1. So if you exhaust to atmosphere, an inlet pressure above 4 atm is overkill.

Note also the "Turbine flow parameter". The greater the inlet pressure, the greater must be the mass air flow and/or the inlet temperature if you want to respect the design parameters of the turbine. So with an inlet pressure of 10 atm, you would need 4 times the mass air flow (or 16 times the inlet temperature !) of the same turbine performing at 2.5 atm inlet pressure.

Also, all turbines have stator vanes (they are also called diffusers), otherwise they wouldn't work (at least, not efficiently). What you are referring to with the turbocharger for Ford diesel engines is "variable-geometry turbocharger" where the angle of the diffuser can be changed to accommodate efficiently a wider range of mass air flow.

 

[Sunfire]

Hi and thank you for your reply!

Note also the "Turbine flow parameter". The greater the inlet pressure, the greater must be the mass air flow

We are looking for a low mass flow turbine; wanted to achieve high-velocity injection by nozzling the inlet gas in at close to sonic velocity. Your recommendations on best ways to achieve this are welcome.

the typical expansion ratio of a radial turbine is 2:1 to 3:1...

Could you elaborate - what would your recommendations be for improving the expansion capability (apart from increasing the rotational speed)

Also, all turbines have stator vanes (they are also called diffusers), otherwise they wouldn't work (at least, not efficiently).

The IHI one quoted above doesn't have them; it comes with a volute inlet manifold. It would be interesting to find out if other small turbochargers come with stator vanes instead.

 

[jack action]

We are looking for a low mass flow turbine; wanted to achieve high-velocity injection by nozzling the inlet gas in at close to sonic velocity. Your recommendations on best ways to achieve this are welcome.

I'm not sure I understand completely how your apparatus is supposed to work. It's not even clear what will be the type of fluid you will used. Is it hot exhaust gas or compressed ambient air? Are you going to let the gas enter freely the turbine or are you designing some sort of nozzle you will put inside the turbine inlet?

Saying that you want a low mass flow, high inlet pressure turbine seems difficult to achieve.

Referring to the previous graph, if you have a low mass air flow and a high inlet pressure, then your "turbine flow parameter" will be small, putting you in the lower end of the y-axis. This means that your turbine will work with a small expansion ratio as well.

Looking at the following graph, you can see a more detailed version of a similar graph, showing the efficiency and turbine rpm as well.

As you can see, the lower are your mass flow and expansion ratio, the lower is your wheel rpm and efficiency.

Could you elaborate - what would your recommendations be for improving the expansion capability (apart from increasing the rotational speed)

What I'm saying is that I don't think you can find any radial turbine that will have an expansion ratio greater than 4:1. So if your fluid enters the turbine at 10 atm, it will exit, at most, at 2.5 atm. That is a lot of energy left inside the fluid that couldn't be recovered by the turbine. In such a case, it would be wiser (if possible) to convert your fluid to a lower pressure, but giving you a higher inlet velocity.

So in summary, you need to match the turbine design with your inlet flow (or vice versa). By flow I mean:

• mass flow rate
• inlet pressure
• inlet temperature

There is an infinite amount of combinations, but they must correspond to the designed "turbine flow parameter" of the turbine. You should aim for a value that will correspond to a high expansion ratio, which is usually the one that will give you the best efficiency.

The IHI one quoted above doesn't have them; it comes with a volute inlet manifold. It would be interesting to find out if other small turbochargers come with stator vanes instead.

Sorry, my mistake, disregard this comment.

 

[Sunfire]

jack action,

thank you for your replies; just looked in Dixon/Hall and see that they define a "turbine flow coefficient" which is the parameter you mention. will need some time to process this information.

Thanks!