BET Migration Tools

BET Migration Tools#

Overview#

The Blade Element Theory (BET) migration tools in Flow360 provide a robust framework for converting legacy V1 BET configurations to the current Flow360 version. This guide outlines the process of migrating BET disk configurations to the latest Flow360 format.

Key Components#

The migration tools consist of two primary functions:

read_single_v1_BETDisk(file_path, mesh_unit, freestream_temperature)#

Constructs a single :class: BETDisk instance from a given V1 (legacy) Flow360 input.

Parameters:

  • file_path (str) – Path to Flow360 JSON file that contains a single BETDisk setting.

  • mesh_unit (LengthType.NonNegative) – Length unit used for LengthType BETDisk parameters.

  • time_unit (TimeType.Positive) – Time unit used for non-dimensionalization.

  • freestream_temperature (Annotated[_AbsoluteTemperatureType, PlainSerializer(func=~flow360.component.simulation.unit_system._dimensioned_type_serializer, return_type=PydanticUndefined, when_used=always), AfterValidator(func=~flow360.component.simulation.unit_system._check_temperature_is_physical)])

Returns:

An instance of BETDisk completed with given inputs.

Return type:

BETDisk

Examples

Create a BET disk with an XROTOR file.

>>> param = fl.BETDisk.from_flow360(
...     file=fl.Flow360File(file_name="flow360.json")),
...     mesh_unit=param.length_unit,
...     time_unit=param.time_unit,
... )
read_all_v1_BETDisks(file_path, mesh_unit, freestream_temperature)#

Read in Legacy V1 Flow360.json and convert its BETDisks settings to a list of :class: BETDisk instances

Parameters:

  • file_path (str) – Path to the Flow360.json file.

  • mesh_unit (LengthType.NonNegative) – Length unit used for LengthType BETDisk parameters.

  • time_unit (TimeType.Positive) – Time unit used for non-dimensionalization.

  • freestream_temperature (Annotated[_AbsoluteTemperatureType, PlainSerializer(func=~flow360.component.simulation.unit_system._dimensioned_type_serializer, return_type=PydanticUndefined, when_used=always), AfterValidator(func=~flow360.component.simulation.unit_system._check_temperature_is_physical)])

Return type:

list[BETDisk]

Examples

Create a BET disk with an XROTOR file.

>>> param = fl.BETDisk.from_flow360(
...     file=fl.Flow360File(file_name="flow360.json")),
...     mesh_unit=param.length_unit,
...     time_unit=param.time_unit,
... )

These functions:

  • Automatically assign units to legacy BETDisk parameters based on the mesh unit.

  • Convert legacy parameter names to the current API format.

  • Create the corresponding Cylinder entity required for each BET disk.

  • Calculate the non-dimensional rotation speed (omega) using freestream conditions.

Usage Examples#

Single BET Disk Migration#

import flow360 as fl
from flow360.component.simulation.migration import BETDisk

# Read and convert single BET disk configuration
my_BETDisk = BETDisk.read_single_v1_BETDisk(
    file_path="./BET_tutorial_Flow360.json",
    mesh_unit=fl.u.m,
    freestream_temperature=300 * fl.u.K,
)

# Use the converted BET disk in simulation
with fl.SI_unit_system:
    params = fl.SimulationParams(
        models=[my_BETDisk],
        # ... other parameters ...
    )

# Modify BET disk properties if needed
params.models[0].omega = 500 * fl.u.rpm

Multiple BET Disks Migration#

import flow360 as fl
from flow360.component.simulation.migration import BETDisk

# Initialize simulation parameters
with fl.SI_unit_system:
    params = fl.SimulationParams(
        operating_condition=fl.AerospaceCondition(velocity_magnitude=10)
    )

# Read and convert multiple BET disk configurations
bet_disks = BETDisk.read_all_v1_BETDisks(
    file_path="./multi_BET_tutorial_Flow360.json",
    mesh_unit=fl.u.m,
    freestream_temperature=params.operating_condition.thermal_state.temperature,
)

# Use the converted BET disks in simulation
params = fl.SimulationParams(
    models=bet_disks,
    # ... other parameters ...
)

# Modify properties of specific BET disks if needed
params.models[0].omega = 500 * fl.u.rpm  # First disk
params.models[1].omega = 750 * fl.u.rpm  # Second disk

Parameter Mapping#

The migration process automatically handles the conversion of legacy parameters to their current equivalents. The following tables show the complete mapping of parameters:

BET Disk Parameters#

Legacy Parameter

Current Parameter

rotationDirectionRule

rotation_direction_rule

numberOfBlades

number_of_blades

ReynoldsNumbers

reynolds_numbers

chord_ref

reynolds_numbers

n_loading_nodes

n_loading_nodes

sectional_radiuses

sectional_radiuses

sectional_polars

sectional_polars

mach_numbers

mach_numbers

lift_coeffs

lift_coeffs

drag_coeffs

drag_coeffs

tip_gap

tip_gap

initial_blade_direction

initial_blade_direction

blade_line_chord

blade_line_chord

Cylinder Entity Parameters#

The following parameters are used to create the associated cylinder entity for the BET disk:

Legacy Parameter

Current Parameter

axisOfRotation

axis

centerOfRotation

center

radius

outer_radius

thickness

height

Note: The cylinder entity is automatically created with:

  • inner_radius set to 0

  • name generated as “bet_cylinder{N}” where N is the disk index

Important Considerations#

  1. Units: The migration process requires specification of the mesh unit and freestream temperature for proper unit assignment.

  2. Geometry Parameters: The tool automatically converts geometric parameters such as:

    • Axis of rotation

    • Center of rotation

    • Radius

    • Thickness

  3. Aerodynamic Data: The migration preserves:

    • Lift coefficients

    • Drag coefficients

    • Mach numbers

    • Reynolds numbers

  4. Tip Gap Handling: The tool supports both finite and infinite tip gap configurations.

Best Practices#

  1. Always verify the converted parameters before running simulations

  2. Ensure proper mesh resolution around BET disk regions

  3. Consider tip gap effects in the simulation setup

Example Configuration#

A typical Legacy BET disk configuration includes:

{
    "BETDisks": [
        {
            "axisOfRotation": [0, 0, 1],
            "centerOfRotation": [0, 0, 0],
            "radius": 1.0,
            "thickness": 0.1,
            "numberOfBlades": 4,
            "omega": 1000,
            "sectionalPolars": [...],
            "twists": [...],
            "chords": [...]
        }
    ]
}
Contents