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Turbomachinery getting started
This getting started guide provides a comprehensive introduction to thermal modeling for turbomachinery applications using Simcenter 3D Thermal Multiphysics.
Introducing boundary conditions
This topic explains the different types of boundary conditions used in turbomachinery simulations and how thermal, shared, and structural conditions are applied through simulation objects, constraints, and loads to represent multiphysics behavior.
Convection boundary conditions
This topic explains what thermal boundary conditions you can use for convection.
Method 1: Surface-based convection boundary conditions
Introducing surface-based convection boundary conditions
This topic explains how to model surface-based convection using Thermal Streams, Thermal Voids, and Thermal Convective Zones, and how to apply them to represent different flow behaviors and heat transfer mechanisms.

Knowledge base articles
Knowledge base articles provide concise, practical guidance for solving thermal, flow, multiphysics, space systems, and turbomachinery modeling challenges in Simcenter 3D.
Space thermal getting started
This getting started guide provides a comprehensive introduction to space thermal modeling using Simcenter 3D Space Systems Thermal (SST).
Turbomachinery getting started
This getting started guide provides a comprehensive introduction to thermal modeling for turbomachinery applications using Simcenter 3D Thermal Multiphysics.
- Getting started with turbomachinery in Simcenter 3D
- Fundamentals of turbomachinery systems
  This topic introduces turbomachinery and explains how gas turbines convert working-fluid energy into mechanical energy or thrust. You will learn how turbomachines are classified, how the Brayton cycle describes gas turbine operation, and how the main gas turbine sections, components, and cooling systems support safe and efficient performance.
- Gas turbine design disciplines and data exchange
  This topic introduces the main engineering disciplines involved in gas turbine design and explains how they exchange data throughout the development process. You will learn how different teams collaborate, what data they produce, and how iterative workflows drive the final engine design.
- Introducing Whole Engine Model (WEM)
  This topic introduces the WEM and explains its role in gas turbine design. You will learn how WEM captures the thermal and structural behavior of the engine, what inputs it requires, and how it supports clearance and mechanical integrity assessments.
- Introducing the user interface
  This topic covers the user interface (UI) in Simcenter 3D Thermal Multiphysics. You will learn how to navigate the modeling environment and how to efficiently use the available tools, menus, and commands to build, set up, and review your models.
- Preparing geometry for WEM
  This topic explains why geometry preparation is critical for WEM analysis. You will learn how to simplify 3D CAD geometry into efficient 2D or hybrid models and how to prepare geometry for meshing and simulation in Simcenter 3D.
- Meshing strategy
  This topic explains how to create finite element models for WEM by combining multiple mesh types and abstraction levels.
- Managing parts and assemblies
  This topic explains how to manage parts and assemblies in WEM using associative geometry, collaborative simulation capability, and integration of submodels into a full engine simulation.
- Condition sequences
  This topic explains how condition sequences define and manage engine operating conditions over a mission cycle in WEM.
- Introducing boundary conditions
  This topic explains the different types of boundary conditions used in turbomachinery simulations and how thermal, shared, and structural conditions are applied through simulation objects, constraints, and loads to represent multiphysics behavior.
  - Thermal coupling
    This topic explains how to model heat transfer between components that are not directly connected through the mesh in WEM simulations.
  - Convection boundary conditions
    This topic explains what thermal boundary conditions you can use for convection.
    - Method 1: Surface-based convection boundary conditions
      - Introducing surface-based convection boundary conditions
        This topic explains how to model surface-based convection using Thermal Streams, Thermal Voids, and Thermal Convective Zones, and how to apply them to represent different flow behaviors and heat transfer mechanisms.
        Create thermal boundary conditions for an aeroengine compressor
        Practice defining thermal boundary conditions for an axisymmetric aeroengine compressor. You will create thermal streams, voids, and convecting zones.
      - Defining thermal streams
        This topic explains how to define and use Thermal Streams to model convective heat transfer, including setup, required inputs, stream types, governing equations, and advanced options for accurate modeling.
      - Connecting thermal streams
        This topic explains how to connect thermal streams.
      - Defining thermal voids
        This topic explains how to define and use Thermal Void to model enclosed fluid regions with simplified thermal behavior, including setup, governing energy equation, required properties, and options to represent heat transfer, capacitance, and interactions with surrounding solids and streams.
      - Defining thermal convecting zones
        This topic explains how to define thermal convecting zones to model heat transfer to a fluid at a known temperature, acting as a fixed-temperature convective sink.
      - Boundary condition ID in expressions
        This topic explains how boundary condition IDs are assigned and modified for streams, voids, convecting zones, and duct labels, including how to renumber or offset IDs for use in expressions.
    - Method 2: Coupled 1D duct fluid network
    - Comparing two methods
      This topic compares thermal streams and 1D duct networks, as well as voids and duct-node approaches, highlighting their differences in workflow, control, and suitability for modeling convective heat transfer in turbomachinery.
    - Modeling mixed flow from two ducts into the thermal stream
      This topic explains how to model mixing of flows from multiple ducts into a thermal stream, including methods using expressions, mock streams, the MIX function, and thermal stream junctions.
    - Relative temperature effects
      This topic explains how to account for total temperature effects in turbomachinery simulations, particularly in systems with rotating and stationary components.
  - Fields, expressions and plugins
    This topic explains how to define boundary condition inputs in Simcenter 3D using fields, expressions, and plugin functions. These tools allow you to model complex, time- and space-dependent behavior efficiently.
  - Radiation modeling
    This lesson explains the two Radiation simulation object types and how each defines radiative enclosures and affects radiation calculation efficiency.
  - Cyclic Symmetry
    This topic explains how to use Cyclic Symmetry in turbomachinery thermal models.
- Solving a model
  This topic explains how to configure thermal-solver settings in WEM, including convergence criteria, discretization methods, integration methods, and axisymmetric-segment control for accurate and efficient thermal analyses.
- Post-processing results
  This lesson introduces post-processing commands to help you review and evaluate simulation outcomes using visualization and data analysis.
- Mechanical integrity
  This topic explains how thermal results from WEM are mapped to detailed component models for structural and mechanical integrity analyses.
- Blade cooling
  This topic explains why blade cooling is critical in gas turbines and how advanced cooling technologies allow turbine components to operate at temperatures above material limits.
- Troubleshooting the model
  This topic explains how to verify FEM quality, material definitions, mesh integrity, and element properties before solving a thermal model.

Introducing surface-based convection boundary conditions

This topic explains how to model surface-based convection using Thermal Streams, Thermal Voids, and Thermal Convective Zones, and how to apply them to represent different flow behaviors and heat transfer mechanisms.

This lesson may include hands-on exercises. Review the Discussion section for background information or click the button to proceed to the practical section.

Discussion

Use surface-based convection boundary conditions to model fluid–solid heat exchange directly on walls. This approach the uses Thermal Streams, Thermal Voids, and Thermal Convective Zones loads.


Boundary conditions	Description	Output quantity	Representation
Thermal Stream (1)	Combine mass flow with convective coupling. Define inlet temperature, heat load (Q), and pressure.	Mass flow, fluid temperature, heat transfer coefficient (HTC), heat load (Q), pressure
Thermal Void (2)	Represent a stagnant cavity with HTC and no fluid connection.	HTC and pressure
Thermal Convecting Zone (3)	Model a solid surface in contact with a fluid at a specified temperature and infinite heat capacity.	Temperature, HTC, and pressure

Setting up convective boundary conditions with Method 1

In a WEM, model the flow network using different convective boundary conditions.

For example, in the highlighted region, you can identify several types of flow:

Main compressor flow — Thermal Streams
Cooling flow — Thermal Streams
Mixing flow — Thermal Voids
Cavity flow — Thermal Voids
Leakage flow — Thermal Streams
External environment — Thermal Convective Zone

Axisymmetric gas turbine cross-section showing airflow, combustion, and cooling paths with labeled thermal regions and convection zones used for fluid–solid heat exchange modeling.

Assign each flow type to the appropriate convection boundary condition to represent the physical behavior accurately.

Hands-on material

To gain experience with the topics discussed here, complete the following:

Define convection boundary conditions at 2D interfaces