Fuel Payload Slosh Noise

On 10 March 2000, we made a presentation to the "Automotive Fuel Systems Beyond 2000" Conference at Dearborn near Detroit, Michigan. The title of the presentation was "Fuel Payload Slosh Noise".

The presentation focused on the control of Fuel Payload Slosh Noise. The other issues dealt with were the:

interaction of experimentation and CFD design of Fuel Filling Systems role of forecourt filling nozzles in the design process.

Click to download AVI (1.0 MB)

Slosh Noise is a new Noise Vibration Harshness (NVH) issue. A Tier 1 supplier had a problem with a new Blow Moulded Plastic Tank they had developed. The noise of the fuel Sloshing was judged by the OEM to be a fail on their NVH Quality Level. The OEM demanded improvement from the supplier or the contract would be lost. We were asked to investigate the problem by the supplier.

We developed a tilt rig capable of simulating the forces applied to the tank due to the braking of a vehicle. A data acquisition unit was used to measure the pressure in selected positions in the tank and assessed the Slosh Pressure over a five-second period after the tilting of the tank. Theoretical Analysis suggested the application of the Impulse-Momentum Principle:

S F.dt = D (m.v)                   

Impulse = Change in Momentum

As a result of the investigations we were able to make recommendations for a modified tank which was adjudged a NVH Quality Level pass. The modified tank had lower Slosh Pressures and no "aftershock" which was a characteristic of the original tank.

Future projects need to embrace both CFD and empirical investigation. We are developing a comprehensive CFD Slosh tool. The aim is to have a full, 3D, CFD tool to predict Slosh. This will ensure our clients do not require the production of multiple prototypes of their products.

Request a copy of the PowerPoint presentation on CD or via email contact us.

There is a requirement to develop the understanding of the Fundamental Fluid - Mechanics of Slosh What is the payback for 100% understanding? Lower Production Costs Simpler designs with less Slosh control inserts Shorter Development Times and OEM confidence in Tier 1 Client Good Experimentation, allied to good CFD, will deliver the ever-higher quality products demanded by the OEM’s.

Fuel tank and filling pipe

We undertook a series of experiments using a 2D tank. The purpose of the experiments was to establish Design Rules for features on blow moulded fuel tanks. The effect of the following features on fluid flow was examined:

• Roof to Wall Radii
• Sloped Roof
• Roof Baffle
• Floor Baffle
• Beach Area

We compared data gathered for each condition with that of an empty tank and could use the results to predict the behaviour of the fluid within the tank as a result. Using the results we obtained we were able to reduce our customer’s development time and prototype tooling costs.

What is the Payback from Tank Manufacturers having Slosh-Avoidance Expertise?

• Less prototype tooling 
• Avoiding $100k to $200k per tool
• Faster Development Time
• Lower Prices to the client
• OEM Confidence in Tier 1 Client to deliver product

Fuel Filling System Design

  CFD & Appropriate Technology

CFD requires good input data. The GIGO Principle applies i.e. If you put garbage in you will get garbage out!  If the Physic is wrong: then the answer will be wrong .  To design a fuel filler system there is a need to understand Forecourt Nozzle characteristics. Particular attention must be paid to the effect of Nozzle Aeration. A common misconception is that all forecourt nozzles are the same. We have undertaken research in the past into nozzle design in general and the causes and effect of nozzle aeration in particular.

Velocity profile through two types of nozzle

To enable CFD to successfully model a fuel filling system the correct fluid characteristics must be known. Our research identified that the Volumetric Flow Rate of different nozzle types varies from 103% to 180% of the Fill Rate. We also found the Nozzle Aeration Rates Vary from 3% to 80% depending on the type of nozzle. This information is essential when using CFD to predict system performance. For more information on our range of services contact us.