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karmavatar June 13, 2011 00:06

Basic Nozzle-Expander Design
4 Attachment(s)
Hi all,
I am proceeding towards design of a nozzle-expander system. Please help me in understanding the output and correct geometry if needed. I have uploaded images showing my input in Vista-RTD, input in CFX and final results of velocity profile.

Expander design
1. I input required parameters as shown in Vista-RTD for the expander and created the Expander geometry in BladeGen. I have included input of each step from Vista-RTD.

Nozzle design
2. I used the nozzle assumption on Pic 1 from Vista-RTD to create a nozzle in BladeGen.

3. I used the inlet velocity triangle on Pic 4 to match the RELATIVE INLET FLOW ANGLE (W2) = 40.66 degrees required by expander to match the nozzle ABSOLUTE FLOW ANGLE.

CFX Input

4.I brought in CFX-MESH for both expander and nozzle and show my input in Pic 6. I input same inlet pressure and temperature as in Vista-RTD and same outlet mass flowrate (0.23 kg/s divided by 13 blade passages = 0.0176 kg/s) as in Vista-RTD.
I used conditions at inlet of expander to be same as inlet of nozzle for the time being since I didn't analyze the nozzle separately (I hope this doesn't affect the flow angle problem I am witnessing in the results!)


5.I have attached the velocity profile I obtain in Pic 7. As I interpret it I can see separation and possibly the inlet flow angle to the expander is not correct?.

6. Please help understand the interpretation from the velocity profile I obtained how to correct the geometry or any input I have mistaken.

Thank you all for your previous help to familiarize myself with the programs and now I need help to understand results and interprete to create a proper geometry.


karmavatar June 15, 2011 01:24

Anybody please to help me on this topic.
Mr. Glenn Horrocks if you could help me please.
Thank you,

ghorrocks June 15, 2011 07:48

But what are you trying to do? Looks like a blade geometry with lots of big separations to me so it does not appear to be operating well.

karmavatar June 16, 2011 01:31

Yes, there are lot of separations. But I am not able to understand how to correct it.
I matched nozzle absolute velocity direction to rotor relative velocity direction and I have see big separation.
Please give me some direction what to check and look for to correct this.
Thank you,

ghorrocks June 16, 2011 08:02

I have no experience in rotating machinery design. Looks like you need to get some textbooks on rotating machinery design.

karmavatar June 17, 2011 19:52

Thanks Glenn.

Anybody who is working on either turbine or compressor blade geometry and simulation, I would appreicate if you could give me a direction on this.
Thank you,

SOONG YOUNG July 2, 2015 21:01

hI karmavatar
I have some difficulties in creating a nozzle in Ansys ,I found you had made it . Did you create the nozzle in the VISTA RTD or you design it in the Bladegen ?
Thank you

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