Hi everyone,

In the latest version of TCAE (25.03v1), it is possible to set new parameters in the SIMULATION/Controls section: the solver max and min iterations (photo attached). What exactly do these iterations correspond to?

Thanks in advance.

Zacharie Prigent

Hello everybody,

I have a few questions regarding TCAE transient simulations.

1) Are the transient simulations robust?

2) Do you have any recommendations for applying transient simulations  to centrifugal compressors?

3) How do I control the recording of intermediate time steps? I haven't found a way to control it in the GUI, and the controlDict file in ../system/ is automatically restored to its previous version (with the adjustableOnEnd option in the writeControl section), even if we manually modified it before running the calculation!

Zacharie Prigent

Hi everyone,

I’m running a steady-state simulation of a centrifugal compressor impeller and I keep running into an issue where the residuals settle but don’t properly converge, even after several thousand iterations. The solution looks stuck, and I’d like to understand if the problem is with my setup, mesh, or solver controls.

Case setup

• Geometry: Centrifugal compressor impeller with inlet passage and outlet

• Mesh: ~1.6 million cells, generated in TurboGrid and exported as cgns into TCAE

• Interfaces: Mixing plane, 7 mixing planes total across 2 interfaces

• Fluid: Air, perfect gas; μ = 1.78e-5, ρ = 1.2, p = 1 atm (defaults)

• Rotation: 110,000 RPM (tested both +111000 and −111000, same behavior)

• Flow regime: Transonic option enabled

Boundary conditions

• Inlet:

  • Total pressure = 1 atm

  • Total temperature = 288.15 K

  • Turbulence intensity = 5% (k = 82.14)

  • Turbulence length scale = 0.015 m (blade height) → ω = 604.207

• Outlet:

  • Mass flow = 0.35 kg/s

• Walls: No-slip, adiabatic, standard wall functions

Solver settings

• Turbulence model: k-ω SST (default values)

• Numerics: Second order, non-orthogonal mesh correction enabled

• Under-relaxation factors: Set to 0.15 (started higher but reduced due to stability issues)

• Physical limits:

  • p: 50,000 – 800,000 Pa

  • ρ: 0.1 – 100

  • v: 0 – 800 m/s

  • T: 250 – 700 K

• Initial conditions:

  • p = 1 atm

  • T = 288.15 K

    v = 0 , 0, 148 Got it from a 1D code as the absolute velocity at the inlet.

  • k = 0.01

  • ω = 100

Problem

Residuals drop initially but then flatten out and refuse to converge further. Monitors also don’t stabilize in a meaningful way, I think the monitors get stuck because the residuals do not drop further. I have tried with the fixed mean static pressure outlet condition as well but still the same thing. One thing I suspect is that I think there maybe be some unsteadiness in the flow which maybe causing this, is there a way to set a pseudo time scale or something. Any help would be appreciated!

Component 5, (Nacelle_Top) and Component 7 (Nacelle_Bottom) are experiencing failure to mesh. Can you take a look? It might be obvious to you.

Here's a download link to the compressed project file for your review. Please see my comment for a better Component map image for reference.

Edit: I've even tried performing the meshing operation using Salome-Meca. Meshing just one stl fails with it too, but unlike TCAE, takes several hours to fail completely. The component 5 (fuchsia) is Nacelle_Top, the patch in question is named Solid_Top_Bell-Mouth_inlet_and_Duct_Surface_08_21_25a.

I suspect Nacelle_Bottom is going to be just as bad, or worse, than Nacelle_Top. It is slightly smaller in diameter, but it's a more complicated surface.

Thanks in advance,

David

The previous iteration of this TCAE project experimented with omitting a central component from the topology, the Duct_Separator, going from the Top_Fan rim (sometimes called a hub, in this case an open outlet interface), through which air not used by the Top_Fan flows from the Top_System_Suction outlet interface, and continues directly to the inlet interface of the Bottom_Fan open rim, skipping the Duct Separator. Confusing, I know, but the Bottom_Fan is upside-down compared to the Top_Fan, so it takes in air not from the shroud inlet interface, as in the case of the Top_Fan, but from the Bottom_Fan's open rim inlet interface.

This iteration is more like the actual setup, Suction, Top_Fan, Duct_Separator, Bottom_Fan, Nacelle, Outlet_Extension. Please see my comment for a more complete image of the Component Map.

Who knows? It might eliminate some setup errors seen previously.

Working through the Check for Errors exercise finally presented only this orange border in the Components Map. Other than TCAE Output messages, there's no textual description of what or where things have gone awry. I'm assuming it's displayed somewhere in the TCAE Output messages, but what should I be looking for? Is it because the component Duct Separator (Co6) is without a partner, present in the group, barely visible, but no interaction with any other?

Just when I thought I had interfaces getting close to being set up with the project saved and closed....upon reloading the project, TCAE quits!

No warnings, no alerts. TCAE just quits.

In anticipation of posting this topic, I uploaded the project and STLs for your review. Please find download links in comments.

Please look for TCAE_07_27_25.zip for the project file and 4448_06_23_25_STL.zip for folders and patches.

Have you any ideas on how to proceed to fix the project?

Please let me know if you have any problems accessing or downloading the zip files.

Thanks in advance,

David

The instructions are as follows:

To create two meridional slices, one for each fan in TCAE, follow these step-by-step instructions:

1. Load the Simulation Results: Open your TCAE project and load the results of your simulation for the fans.

2. Select the First Fan:

   • In the Pipeline Browser, select the mesh or results corresponding to the first fan.

3. Add a Meridional Average Filter:

   • Go to the Filters menu.
   • Select "Turbomachinery" and then choose "Meridional Average."

I am not presently seeing any geometry in the Pipeline Browser, so, I tried double-clicking the individual STLs making up the component in CFD Mesh, (later realizing selecting multiple elements is not supported) then going to the Filters menu, selecting Turbomachinery,  the option "Meridional Average."  is greyed out, please see image.

I'm still at the beginning setup phase; loading geometry and tweaking types and interfaces. I have no results of any simulation to load. I have not tried to create a mesh yet. Is that (or something else) I need to do first besides read the manual?

Thanks in advance

David

Please see my comments, below, for Fan and Duct Separator info.
Question:  For the case with a closed bottom system inlet,  is the Reference Frame of the Top Fan Open Rim interface, that's the second "surface" boundary that the incoming air encounters on it's way to join the other half; is it static, rotating, or freestream? Shared inlet air flows through it to the inlet of the bottom fan. How about it's type?

Same question for bottom fan except, because it is upside-down compared to the top fan; what is the reference frame of the Bottom Fan Open-Rim Interface? While we're at it, how about the Bottom Fan Shroud Interface? Closed bottom inlet, remember?; are they static, rotating, or freestream? Type?

From the shared inlet at the top of an axi-symmetric radial discharge duct, aka Volute or Hull, one-half of the flow first enters between the Top Fan Shroud  and  Rim, then blade passages, exits the fan, rides a cosine curve down to join the other half geometrically  mirrored about the X-axis, which has become the Bottom Fan discharge, combines radially without colliding too much, then downward smoothly toward axial, but not exactly.

I have an idea for dynamic stability, could be combined with distance between cg and center-of- lift asymmetry.

Closed Bottom Duct Surface and Duct Separator not shown for clarity. No bottom inlet opening for first simulation case. System outlet is a 0.83 [m] outside diameter annulus of appropriate area for combined fan discharge.

The Fans: each identical, one-piece solid poly-surface Boolean union of rim, shroud, and blade array has open rim, no hub, mounted to a 0.315 [m] OD carbon fiber rim bicycle wheel.

Thanks in advance.

David

is it possible with TCAE to make “overmesh” meshes?

Hi,

I have a problem with report at the end?

Program made all 3000 iteration ( about 1.200.000 pcs), but at the end is allways problem with the report: (see picture below).

Thanks.

Hi,

I have a problem with report at the end?

Program made all 3000 iteration ( about 1.200.000 pcs), but at the end is allways problem with the report: (see picture below).

Thanks.

I have been trying to run the the NASA HECC tutorial provided by TCAE. The tutorial has a very dense mesh and takes verylong to run and make a speedline. In order to save computation time I tried two methods:

1. I reduced the mesh and ran the simulation for only one point on the speedline (the one with the highest efficiency). 

2. I ran the whole tutorial as is and just skipped the first two points 

Both methods do not result in convergence at all. I am not sure what is going wrong. I have tried to adjust the relaxation factors annd still nothing works to get convergence.

What can i do to fix this?

Hi,

I'm a new user of TCAE-Lite.

I've setup a pump case and the "check" button says the case has been setup correctly. However it fails to mesh.

The same error occurs when running the f1 tutorial case.

Any advice would be appreciated,

Thanks,

Tom