Windshield velocity distribution measurements using low powered 2D FlowLite

In the automotive industry, customer clinics and surveys have revealed the importance to the customer of good demist/defrost performance in their vehicle. The expectation is for the ice on the outside, and mist on the inside, to be rapidly and evenly cleared, with no significant dips or peaks in the pattern.

Traditionally, the defrost performance and pattern is determined by “soaking” a vehicle overnight in a cold room, and then spraying water to form a uniform layer of ice over the whole windshield. The engine is subsequently started and the clearing pattern is recorded as it progresses up the windshield. The repeatability is sometimes poor, and due to the high thermal inertia of a vehicle, only one test per day is generally possible. A new technique developed and employed by Visteon GmbH is described that correlates extremely well with the cold room results, but relies simply upon measuring the velocity distribution of the air as it flows up the windshield. The principal benefit of the technique is that it only takes 2 hours to complete.