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2024, June | Article by: Michele Merelli

Waterproofing Car AC Air Intakes: CFD Simulations Prevent Water Intrusion

Ensuring proper automotive HVAC system waterproofing is critical for occupant safety and comfort. Water entering the cabin air intake can quickly lead to fogged windows, decreased air quality, and driver distractions - potentially causing accidents. But preventing rain intrusion into these intakes is a tough engineering challenge.

Key takeaways

  • Rainwater entering car HVAC air intakes causes major safety issues like foggy windows
  • Particleworks CFD showed adding a simple wall reduced cabin water overflow by 90%
  • An optimized ductwork-style cover design blocked around 90% of total water infiltration

Most car AC systems pull fresh air from vents located between the windshield and hood. However, this frontal area also sees heavy rain and water runoff during storms, especially when the car is on an incline. Without effective waterproofing, this rainwater can easily infiltrate the HVAC system and enter the cabin.

To tackle this issue head-on, engineers used Particleworks computational fluid dynamics (CFD) software to simulate potential water intrusion paths. Whole vehicle CFD rainstorm models confirmed the windshield and hood as primary sources of water flowing towards the cowl air intake zone at a 15-degree uphill angle.

A detailed cowl section model was then created to inspect the air intake geometry. Initial simulations on the original design revealed two key infiltration risks: direct incoming droplets, and overflow of accumulated rainwater from surrounding sloped surfaces. Both could allow significant water into the cabin HVAC system.

Waterproofing Car AC Air Intakes: CFD Simulations Prevent Water Intrusion

Seeking to block these intrusion paths, two new waterproofing concepts with physical barriers were evaluated using CFD. The first added a simple wall along the air intake's bottom edge. While basic, CFD results showed this wall dramatically reduced cabin water overflow by 90% compared to the original geometry. However, the wall alone could not sufficiently block incoming droplets from above. The engineers therefore designed a second countermeasure installing an overhanging cover inspired by range hood ducting. This cover successfully shielded both overflow and droplet streams.

Quantitative CFD data revealed the ductwork-style cover reduced total air intake water infiltration by around 90% versus the original design. This optimized geometry could almost entirely prevent rainwater intrusion into the car cabin HVAC system. By combining fundamental physics insights with powerful Particleworks CFD modeling, the engineering team rapidly iterated on robust waterproofing solutions from initial concept to final design. This comprehensive simulation-driven workflow is crucial for cost-effectively optimizing automotive air intake waterproofing and ensuring maximum occupant safety.

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