Dear guys.

I am going to compare my resutls of rotor 37 given in examples of turbogird to that of nasa's results. I would like to know that is the geometry of rotor 37 is real or simplified for sake of meshing ( i am not talking about simplification that is related to removal of fillets etc).

BTW I am very much impressed with the mesh turbogrid produced (penelty of topologies). Is turbogrid able to mesh the actual geometries as easily as those given in examples?

Thanks

SA

Hi SA,

the geometry of R37 is the same of course.... you can find it also in the meriodional coordinates in the paper of Reid and Moore; Performance of Single-Stage, Axial-Flow Transonic Compressor With Rotor and Stator Aspect Ratios of 1.19 and 1.26 Respectively, and with Design Pressure Ratio of 2.05. Tech Rep. TP-1338, NASA, 1980. that u can download it from the ntrs server.

i simulated the rotor 37 as it is given in the tutorial (turbogrid & CFX) and it everything seem to be good (position of shock, pressure ratio, ....)

for me, if u have access to a real turbomachinery solver, it would be nice for you coz they are more specialized cfd tools than the cfx is.

Regards,

Noureddine

Dear Noureddine,

thanks for your valuable comments. Could you please names of those solvers which are specific to turbomachinery.

Regards SA

Dear SA,

there is a lot of turmochainery codes, hereafter is just few of them:

1- BTOB3D, NEWT, Professor William Dawes, Cambridge University, http://www.conceptseti.com/Education/cor_cfd.htm

2- UNSTREST, professor J. D. Denton, Cambridge University, "The Use of a Distributed Body Force to Simulate Viscous Effects in 3D Flow Calculations," ASME Paper No. 86-GT-144.

4- NASA Turbomachinery codes, APNASA, H3D, SWIFT, MSU TURBO, (Dr. Adamczyk, J. J., Dr. Chunill Hah, Dr. Rodrick V. Chima, Mississippi State University, respectively), http://www.grc.nasa.gov/WWW/RTT/AnalysisCodes.html

5- TFLO, J, Yao, http://aero-comlab.stanford.edu/jxyao/research.html

6- AU3D, A. I. Sayma; M. Vahdati; L. Sbardella; M. Imregun, http://citeseer.ist.psu.edu/526223.html

7- TRACE, http://www.dlr.de/at/en/desktopdefau...123_read-3615/

But there is more, i dont remember more,

if u r in USA, u can get a lot of them free.

Enjoy,

Noureddine

[zjvskobe]

How to get one of them?

[sfallah]

Originally Posted by Noureddine
;88806

Hi SA,

the geometry of R37 is the same of course.... you can find it also in the meriodional coordinates in the paper of Reid and Moore; Performance of Single-Stage, Axial-Flow Transonic Compressor With Rotor and Stator Aspect Ratios of 1.19 and 1.26 Respectively, and with Design Pressure Ratio of 2.05. Tech Rep. TP-1338, NASA, 1980. that u can download it from the ntrs server.

i simulated the rotor 37 as it is given in the tutorial (turbogrid & CFX) and it everything seem to be good (position of shock, pressure ratio, ....)

for me, if u have access to a real turbomachinery solver, it would be nice for you coz they are more specialized cfd tools than the cfx is.

Regards,

Noureddine

Dear all,
Can you list boundary condition for setting up cfx to simulating NASArotor37 in steady mode?
Any assumed boundary condition leas to overflow, help me please. I do whatever I know, but I did not reach any converged solution.

[sfallah]

Dear all,
Can you list boundary condition for setting up cfx to simulating NASArotor37 in steady mode?
Any assumed boundary condition leas to overflow, help me please. I do whatever I know, but I did not reach any converged solution.

[Opaque]

It will greatly help if you describe the operating condition range for R37, and what operating point you are trying to model. The boundary conditions may depend on what point on the speedline you are trying to obtain.

[sfallah]

Dear Opaque; Nominal operating condition is selected according to suggestion of AIAA paper:"Fully Coupled Fluid-Structural Interaction of a Transonic Rotor at Near-Stall Conditions Using Detached Eddy Simulation":
Total inlet pressure=17.7 (psi)
Outlet Mass flow rate(for complete rotor)= 20.19(kg/s), Outlet Mass flow rate (Per component)=20.19/37=0.5456
Total inlet temp=519 (R)
Reference pressure= 1(atm)
My grid contain about 600000 element for on blade passage, physical time step in steady simulation assumed 0.0001s,
I used Geometry of NASA 37 which exist in turbogrid tutorial. I test it in different inlet and outlet domain length(by extending original geometry in BladeGen) Because of "back flow warning at outlet"
BUT THE OVERFLOW PROBLEM STILL REMAINS. PLEASE HELP ME!!!!!
Maximum Mach number gradually increased and finally reached overflow condition!!!!!!
BUT THE OVERFLOW PROBLEM STILL REMAINS. PLEASE HELP ME!!!!!
In solution procedure, first, Mach Number increased gradually, then Notice:"a wall hase been placed at portion of an outlet..." appears in monitor screen and finally :Overflow!!!!!!
Where is my mistake??????What is its solution?????

[Opaque]

That helps; however, the following will help as well: angular velocity and inlet flow angle.

How was the timestep selected ? Guess, or some physical insight ? You can let the software autocompute the physical timescale which for a rotating domain may end up about 0.1 / Angular velocity.

Is this operating point near choke, peak performance, or stall/surge ? Obtaining solutions for compressor could be a tricky enterprise near choke using a mass flow outlet boundary condition unless you use the newer Exit Corrected Mass Flow released in R15.

If you have ANSYS CFX R14.5 or later, there is a tutorial running R37 which converges w/o difficulty. You should be able to replicate such calculations.

[sfallah]

Dear guys
I am simulating transonic flow past Rotor NASA37, but some problem and challenges is happened during preparing setup and running simulation.
1- I can not reach nominal condition(mass flow rate=21 kg/s and pressure ratio:2.1) by inlet total pressure: 1 atm and outlet static pressure:106.5 kpa.
2- less and more outlet static pressure leads to worse condition which mass flow rate and pressure ratio goes away from nominal condition.
3- Isentropic efficiency can not goes upper than 0.8 under mentioned boundary condition. Whereas, nominal isentropic efficiency is 0.88.
4- I have inlet total pressure, nominal mass flow rate and nominal total pressure ratio. what is the best choice for boundary condition?
5- What is the best choice for inlet and outlet length?
6- How, I can measure efficiency at leading and trailing edge instead default condition(inlet and outlet)?. I guess that extension of inlet and outlet leads to efficiency loss.
please help me!!!

[sfallah]

Dear All
What is the best outlet boundary condition for transonic(subsonic inlet and outlet but transonic passage) compressor and in general transonic turbomachines? why?
I would like to have specified inlet mass flow rate. I use total pressure(because of more stable and better convergence behavior than inlet mass flow rate) at inlet but by applying static pressure at outlet, desired mass flow rate is not be obtained.
My case is Nasa 37 rotor which outlet length is short. using k-omega sst and steady-state option, I have not converged results but using k-epsilon convergence attainment is easy. I guess that its reason is static outlet boundary condition which forced at non-uniform flow location (outlet).
Please help me!!!

[pauldarla89]

hi sfallah,
can u tel me how you calculated the velocity inlet in terms of m/s from rad/s. your help is appreciated.

[Red Ember]

Originally Posted by sfallah

Dear All
What is the best outlet boundary condition for transonic(subsonic inlet and outlet but transonic passage) compressor and in general transonic turbomachines? why?
I would like to have specified inlet mass flow rate. I use total pressure(because of more stable and better convergence behavior than inlet mass flow rate) at inlet but by applying static pressure at outlet, desired mass flow rate is not be obtained.
My case is Nasa 37 rotor which outlet length is short. using k-omega sst and steady-state option, I have not converged results but using k-epsilon convergence attainment is easy. I guess that its reason is static outlet boundary condition which forced at non-uniform flow location (outlet).
Please help me!!!

Look, sfallah!
Point 1: The paper you've got BC out is called "Fully Coupled Fluid-Structural Interaction of a Transonic Rotor at Near-Stall Conditions Using Detached Eddy Simulation". Near-stall conditions imply complicated case that was treated via detached eddy simulation (Transition Model ). So that BC are not fit to your case
Point 2: You have no angular velocity and flow direction as it was mentioned before, so your BC are not complete... These values can change convergence drastically