Conclusions will be presented first to accommodate readers with limited time. For those interested in a deeper dive, the following sections provide background on aeroacoustics and a detailed explanation of the data collection process.
Conclusions
On-road testing effectively identified trends among the evaluated anti-buffeting devices, demonstrating that a commercially available solution, as shown above, successfully reduces interior cabin buffeting in a 2019 Porsche GT3 RS.
To achieve more controlled and precise evaluations, future testing should incorporate wind tunnel experiments and/or computational fluid dynamics (CFD). These methods offer a stable environment and can provide deeper insights into the flow physics affecting the dBA results.
Investigation Overview
Focus:
- Exploring ground vehicle aeroacoustics with an emphasis on buffeting mitigation
- Assess aeroacoustic behavior under real-world driving conditions
- Explore and evaluate potential solutions to improve cabin comfort
- Conducted on public roads at legal speed limits
- Utilize objective decibel measurements
- Summarize existing anti-buffeting solution(s)
- Propose new anti-buffeting solution(s)
- Document and analyze road-test results
Science Review: Aeroacoustics and Buffeting
Aeroacoustics Definition:
- Studies the propagation of sound through air and its interaction with surfaces
- A low-frequency booming sound inside a vehicle cabin caused by disrupted airflow when windows or sunroofs are open
- Airflow over the A-pillar impinges on the B-pillar, creating oscillating pressure fluctuations in the cabin.
- The resulting pressure waves lead to discomfort
- Buffeting is intensified due to the vehicle's aerodynamic design, optimized for performance rather than noise reduction.
Testing
Driving Conditions:
- Public roads, adhering to posted speed limits
- Temperature and atmospheric pressure during testing will be recorded to ensure repeatability and context for results
- Subjective evaluation of buffeting intensity
- Decibel levels measured using DecibleX app via an Apple iPhone
- 2019 Porsche (991.2) GT3 RS
- Anti-buffeting device mounted on passenger side
- Passenger side window lowered, only
Test day conditions:
- Test Date: 7Dec24
- Phone Location: Inboard passenger cup holder
- Phone Orientation: Microphone facing upwards
- Temperature: 26 F
- Pressure: 30.41" Hg
- Humidity: 69%
- Wind Conditions: None
- Speed: ~70 mph
- App: Decibel X
- App Version: v9.9.0 (17537)
- OS: iOS
- OS Version: 16.2
- Phone Version: iPhone Mini 13
Existing Solutions & Unique Solutions: Anti-Buffeting Devices
Anti-Buffeting Device Procurement:
- Devices will not be purchased
- Devices will be reverse-engineered using reference images sourced online
- “Current Solutions” is a geometry that represents ALL current solutions
- The current solutions have relatively the same shape
- Prototypes will be 3D printed using PLA on a Prusa MK4 printer
- Test components will be temporarily attached with painter’s tape for easy adjustments and removal.
Company | Cost | Material | Attachment Type | URL |
| Versus Engineering | $295.00 | Carbon Fiber | 3M VHB Double-Sided Tape | |
| Fabspeed | $326.95 | Carbon Fiber | 3M VHB Double-Sided Tape | |
| Rennline | $249.00 | Carbon Fiber | 3M Adhesive | |
| Rennline | $95.00 | Aluminum | 3M Adhesive | |
| AutoQuest Motorsports | $179.95 | Aluminum | Double-sided tape | |
| DB Carbon | $386.00 | Carbon Fiber | Not available | DB |
Test Results
Please observe the data for the “strakes” (highlighted in green). There appears to be a reduction in dBA over time at specific data points. It is likely that the vehicle began executing a slow, wide left-hand turn, introducing a yaw condition. This change in orientation may have altered the local flow field, reducing the strakes' aerodynamic influence and contributing to the observed decrease in noise levels.
The "current solutions" approach involves analyzing and reverse-engineering what is commercially available to derive an "average shape." This representation serves as a general approximation of existing market options, allowing for analysis without needing to purchase or physically test each product.
The unique anti-buffeting designs, including sawtooth edges, strakes, vortex generators (VGs), single airfoil, and dual airfoil configurations, were developed leveraging aerodynamic expertise.
The min, max, peak and average dBA for each device tested. Max dBA refers to the highest sustained sound level measured during a defined time period.Peak dBA represents the absolute highest instantaneous sound level measured during a recording or monitoring period.
The variation in dBA levels compared to the baseline condition, which was measured without any aeroacoustic devices. This comparison illustrates the effectiveness of the tested devices.
Reducing the decibel level by 3 dBA does not equate to a sound that feels three times quieter; instead, perceived loudness changes on a logarithmic scale. To provide clarity, the changes in decibel levels are translate to perceived changes in sound, helping to bridge the gap between measured data and human perception.
Last edited:
