Design Optimization of an Emissions Sample Probe Using a 3D Computational Fluid Dynamics Tool Ford Motor Company

Format:

Conference/Event

Author/Creator:

Zhang, Zhang, author.

Contributor:

Tennison, Paul

William, Ruona

Yi, Jianwen

Conference Name:

SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2013

Summary:

Emissions sample probes are widely used in engine and vehicleemissions development testing. Tailpipe bag summary data is usedfor certification, but the time-resolved (or modal) emissions dataat various points along the exhaust system is extremely importantin the emission control technology development process. Exhaust gassamples need to be collected at various locations along the exhaustaftertreatment system. Typically, a tube with a small diameter isinserted inside the exhaust pipe to avoid any significant effect onflow distribution. The emissions test equipment draws a gas samplefrom the exhaust stream at a constant volumetric flow rate(typically around 10 SLPM). The sample probe tube delivers exhaustgas from the exhaust pipe to emissions test equipment throughmultiple holes on the surface of tube. There can be multiple rowsof holes at different axial planes along the length of the sampleprobe as well as multiple holes on a given axial plane of thesample probe. In a traditional sample probe design, there aremultiple planes of holes along the length and several holes evenlydistributed on a given plane with a constant hole size. It wasobserved that the exhaust gas sample composition detected utilizinga traditional sample probe design may not accurately represent thegas composition in the exhaust system especially for samples takenfrom a larger diameter exhaust pipe.In this study, a systematic numerical investigation wasconducted to characterize the mass flow distribution for differentemissions sample probe designs used in 3.5\mi and 8\mi exhaust pipeapplications. First, the numerical investigation focused on theeffects of the number of holes in each axial plane (or row alongthe circumference on the tube surface) and on the number of rows ofholes (along the tube length). Next, the effect of location andorientation of the sample holes, as well as exhaust mass flow rateeffects were studied. Then, the effect of sample hole size onsample mass flow rate distribution along the length of theemissions sample tube was investigated. In the end, the sample holesizes were optimized for both 3.5\mi and 8\mi diameter exhaust pipeapplications. Numerical results showed significant improvement inthe mass flow rate distribution as the number of holes on a givenaxial plane in an emissions sample probe tube was reduced from 3holes to 1. An improvement in the mass flow rate distribution wasalso found when the number of rows along a column was reduced.Additionally, for a longer sample probe tube in a large diameterexhaust pipe (8\mi), sample probe tube diameter also plays animportant role in achieving uniform mass flow ratedistribution

Notes:

Vendor supplied data

Publisher Number:

2013-01-1571

Access Restriction:

Restricted for use by site license