Summary for: AirgapThermalModel < ThermalModelElement

Class summary

AirgapThermalModel Simple model for airgap heat transfer.

Adds a node to the parent model, corresponding to the airgap temperature.

The heat transfer coefficient is calculated assuming cylindrical stator and rotor surfaces. In case the ‘active’ area facing the airgap is smaller than that of a cylinder (example: stator slot openings modelled as non-conductive, resulting in heat transfer from the tooth-tip area only), the heat transfer coefficient on the corresponding side (stator/rotor) is increased to compensate by this.length_factor_static and/or this.length_factor_moving.

Windage losses are estimated with this.estimate_windage_losses and lumped to this.node.

Properties

.boundary_length_moving Computed length of moving boundary.

.boundary_length_static Computed length of static boundary.

.connection_moving Node-FEA connection.

A BoundaryConnection object linking the airgap node to the airgap-facing edges of the FEA model, moving component of this.gap.

.connection_static Node-FEA connection.

A BoundaryConnection object linking the airgap node to the airgap-facing edges of the FEA model, static component of this.gap.

.coolant_material Coolant material object.

A CoolantMaterialBase object. For now, properties are evaluated at 20.

If string or char, the material is set to SimpleCoolantMaterial.create(this.coolant_material) in this.initialize.

.correction_coefficient Correction coefficient for heat tranfer

coeff.

.gap Parent SlidingAirgapBase object.

.AirgapThermalModel/length_factor_moving is a property.

.AirgapThermalModel/length_factor_static is a property.

.magnetic_model Parent MotorModelBase object.

.n_moving Moving-side FEA nodes.

.n_static Static-side FEA nodes.

.node Node corresponding to airgap temperature.

.surface_roughness Surface roughness.

Used in windage loss ccomputation.

.thermal_model Parent thermal model.

Methods

Class methods are listed below. Inherited methods are not included.

.calculate_and_set_heat_transfer_coefficient Calculate and/or set h.

calculate_and_set_heat_transfer_coefficient(this, arg) is equivalent to calling h = calculate_heat_transfer_coefficient(this, arg); this.heat_transfer_coefficient = h; this.set_heat_transfer_coefficient(h);

.calculate_heat_transfer_coefficient Calculate heat transfer coefficient.

h = calculate_heat_transfer_coefficient(this, summary) calculates the heat transfer coefficient from the gap dimensions (properties of this) and summary.rpm.

h = calculate_heat_transfer_coefficient(this, h), where h is numeric, is a convenience syntax returning the given value.

.estimate_windage_losses Estimate windage losses in the airgap.

P = estimate_windage_losses(this, summary)

Estimate windage losses according to Saari (1995).

The results are directly proportional to this.roughness, so setting the value to 0 will return zero losses.

.AirgapThermalModel/initialize is a function.

initialize(this)

.recompute Compute heat transfer coeff and windage.

Computes and sets the heat transfer coefficient with this.calculate_and_set_heat_transfer_coefficient, and computes the windage losses with this.estimate_windage_losses and adds them to this.node.heat_source, diided by the number of symmetry sectors.

.AirgapThermalModel/recompute_radiative_heat_transfer_coefficient is a function.

recompute_radiative_heat_transfer_coefficient(this, thermal_solution, varargin)

.set_heat_transfer_coefficient Set heat transfer coefficient.

set_heat_transfer_coefficient(this, h) sets the heat transfer coefficient h to the inner and outer surfaces.

** NOTE the coefficient is defined as the heat transfer coefficient from one of the surfaces into the gap air, not the overall surface-to-surface coefficient.

Furthermore, the value is expected to refer to solid cylindrical surfaces. This is adjusted to account for differences in the size of the actual boundary, such as only the stator tooth tip included in the actual boundary connection (in which case this.connection_static.heat_transfer_coefficient will be larger than h).