Work / TH-01

TH-01

Status · Fictional studyPowertrain cooling

Thermal Envelope

Hypothesis: A shorter duct with a faster area expansion can deliver a comparably uniform velocity at the radiator core, freeing packaging length, provided the flow stays attached through the expansion.
Study scope: Radiator duct geometry only. Coolant circuit, pump and motor losses are inputs, not variables.

02Problem and constraint

A power-electronics and motor package sits close to the front axle. The radiator must reject the heat from both, but the available length between the inlet opening and the core is limited by a structural member. A conventional long, gentle duct does not fit.

Programme constraint

Core size is fixed by supplier availability. The duct must clear the side structure and keep coolant outlet temperature under an illustrative limit of 85 °C at the design duty point.

03Instrumentation and method

Instrumentation

K-type thermocouples on the core inlet and outlet faces (3 × 4 grid)
RTDs in the coolant inlet and outlet
Differential pressure across the core and across the duct
Hot-wire traverse upstream of the core to map velocity uniformity

Method

1Close the heat balance first: heat rejected by the coolant should equal heat gained by the air, within sensor uncertainty. If it does not, the data are not yet usable.
2Rank duct variants in CFD, then build a short-list as scale parts for the tunnel and the cooling rig.
3Judge each duct by core-face velocity uniformity and by pressure drop, because a duct that is uniform but chokes the flow is no gain.

04Annotated visualisation

Exploded view of the cooling path. Switch between a long straight duct and a short expanded duct to compare how evenly the core face is loaded.

Fictional · illustrative

FIG 1Exploded cooling path

Band brightness = relative air velocity at the core face. Uniformity index (min / mean): 0.82.

FIG 2Core-face velocity profile

Relative velocity across the core height

Duct ADuct B

Hover, tap or focus the chart and use ← → to read values.

05Example data and assumptions

Illustrative study parameters. Values are invented for the fictional concept and are not measurements.
Parameter	Duct A (long)	Duct B (short)	Unit
Duct length	420	310	mm
Expansion half-angle	7	13	°
Core-face uniformity index	0.82	0.71	—
Duct pressure drop	lower	higher	rank

Illustrative study parameters. Values are invented for the fictional concept and are not measurements.

Assumptions

Steady heat load at a single duty point; no transient soak.
Air properties at 25 °C, sea level.
Core performance taken from supplier characteristic, not re-measured.

06Trade-offs, limits, verification

Trade-offs

Shortening the duct recovers packaging length, but a steeper expansion risks separation and a less uniform core face.
A vane in the expansion can restore uniformity at the cost of pressure drop and manufacturing complexity.
More inlet area helps cooling but adds drag; this study treats drag as a constraint to hand to the aerodynamics team.

Limitations

Uniformity index is a single scalar and hides where the cold spots are.
Recirculation of hot exhaust air is not modelled.
Result is for one duty point and one ambient temperature.

What we would verify in real-world testing

Heat balance closure on a cooling rig with the actual core
Uniformity with a velocity traverse at the real inlet opening
Behaviour in a tunnel with a moving floor, where the inlet sees a boundary layer

07Related

Related capability

03 Powertrain

Next study

VD-02 Lateral Response

Contact

Discuss a programme

Thermal Envelope

Hypothesis

A shorter duct with a faster area expansion can deliver a comparably uniform velocity at the radiator core, freeing packaging length, provided the flow stays attached through the expansion.

Study scope

Radiator duct geometry only. Coolant circuit, pump and motor losses are inputs, not variables.

Parameter

Duct A (long)

Duct B (short)

Unit

Duct length

420

310

Expansion half-angle

Core-face uniformity index

0.82

0.71

—

Duct pressure drop

lower

higher

rank