Total temperature effects

The total temperature effects can be modeled in one of the following ways:

Neglect Wall Rotation

Use this option when the components that surround the fluid are stationary or when the components are rotating at low speeds, for example in heat transfer to a stator. The specified fluid temperature is assumed to be the absolute total temperature, Tt,abs.

1. Stator2. Absolute fluid velocity

The static temperature, Ts, is determined from the static enthalpy, hs, using the following equation:

hs (Ts) = ht (Tt,abs) – (vΦ2+vax2)/2

where:

• ht is the total enthalpy.

• vΦ is the fluid swirl velocity.

• vax is the fluid axial velocity.

Correct for Wall Rotation

Use this option when the components that surround the fluid are rotating. For Two-Sided Total Temperature Effects, the speed of the two components can be different. The specified fluid temperature is assumed to be the absolute total temperature.

	1. Rotor with a wall velocity, u2. Relative fluid velocity

The relative total temperature, Tt,rel, is determined from the total enthalpy using the following equation:

ht (Tt,rel) = hs (Ts) + ((u – vΦ)2+vax2)/2

The relative total temperature is related to the absolute total temperature using the following equation:

Tt,rel = Tt,abs + ΔTrel

where ΔTrel is the relative temperature difference.

Relative Temperature Reference Frame

Use this option when components that surround the fluid are rotating. For Two-Sided Total Temperature Effects, the speed of the two components must be identical. The specified fluid temperature is assumed to be the relative total temperature, Tt,rel.

The static temperature is determined from the static enthalpy using the following equation:

hs (Ts) = ht (Tt,rel) – ((u – vΦ)2+vax2)/2

The total absolute temperature is determined from the following equation:

ht (Tt,abs) = hs (Ts) + (vΦ2+vax2)/2

For all three methods, you can specify one of the following: the swirl velocity, vΦ, the swirl ratio, ΧS = ωfluid/ω, or the relative temperature difference, ΔTrel.

When you specify the swirl ratio, the thermal solver computes the swirl velocity as follows:

vΦ = ΧSωr

When you specify the relative temperature difference, the thermal solver computes the swirl velocity by solving the equation that relates static enthalpy to total enthalpy. Assuming constant specific heat, cp, and an ideal gas, it is given by the following equation:

Where do I find it?

You specify the total temperature effects in the following boundary conditions:

• One-Sided Total Temperature Effects and Two-Sided Total Temperature Effects types of the Duct Flow Boundary Conditions simulation object

• Thermal Convecting Zone load

• Thermal Stream load

• Thermal Void load

How do I

Create a duct flow network

Create a thick wall duct flow network

Create a duct flow network and model heat transfer using 2D shells

Connect the duct network to the 3D flow domain

Create a duct flow network and model heat transfer using 3D solid elements

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Understanding ducts and area definition

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Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

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Total temperature effects, Simcenter 3D 2021.1 Series

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