Flow measurements across an automotive catalyst monolith situated downstream of a planar wide-angled diffuser

Abstract

Flow measurements are presented across an automotive catalyst monolith situated downstream of a planar wide-angled diffuser. Particle image velocimetry measurements were obtained in the diffuser and the flow distribution within the monolith was obtained from hot wire anemometry at the monolith exit. Flow separation at the diffuser inlet resulted in the formation of a jet that traversed the diffuser before spreading just prior to entering the monolith. The jet featured a potential core and saddle-type velocity profiles. A free shear layer separated the jet core from two large recirculation regions that developed in the diffuser narrowing the potential core. The flow field in the main body of the diffuser was observed to be independent of Re in contrast to that within the monolith. Increasing monolith length gave greater flow uniformity in the monolith as a consequence of jet spreading. Comparing the axial velocity flow profiles ∼ 3 mm upstream of the monolith to that downstream showed that significant flow redistribution occurred as the flow entered the monolith, resulting in more flow entering peripheral channels. It is inferred that pressure loss arising from oblique entry into monolith channels significantly affects the flow distribution within the monolith.

Keywords

particle image velocimetry automotive catalyst monolith planar wide-angled diffuser oblique entry pressure loss flow maldistribution

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References

Weltens

Bressler

Terres

Neumaier

Rammoser

, ‘Optimisation of catalytic converter gas flow distribution by CFD prediction’: 131–151 SAE paper 930780, 1993. Also published in SP-957.

Benjamin

S. F.

Clarkson

R. J.

Haimad

Girgis

N. S.

, ‘An experimental and predictive study of flow in axisymmetric automotive exhaust catalyst systems’ SAE Trans. J. Fuels Lubricants 105 4 (1996): 1008–1019.

Shah

R. K.

London

A. L.

, Laminar flow forced convection in ducts (New York: Academic Press 1978).

Shah

R. K.

, ‘A correlation for laminar hydrodynamic entry length solutions for circular and noncircular ducts’ Trans. ASME, J. Fluids Eng. 100 (1978): 177–179.

Benjamin

S. F.

Haimad

Roberts

C. A.

Wollin

, ‘Modelling the flow distribution through automotive catalytic converters’ Proc. IMechE, Part C: J. Mechanical Engineering Science 215 C4 (2001): 379–383 DOI: 10.1243/0954406011520779.

Benjamin

S. F.

Zhao

Arias-Garcia

, ‘Predicting the flow field inside a close-coupled catalyst—the effect of entrance losses’ Proc. IMechE, Part C: J. Mechanical Engineering Science 217 C3 (2002): 283–288 DOI: 10.1243/095440603762870036.

Küchemann

Weber

, Aerodynamics of propulsion (New York: McGraw-Hill 1953).

Persoons

Vanierschot

Van den Bulck

, ‘Oblique inlet pressure loss for swirling flow entering a catalyst substrate’ Expl Therm. Fluid Sci. 32 (2008): 1223–1231.

Quadri

S. S.

Benjamin

S. F.

Roberts

C. A.

, ‘An experimental investigation of oblique entry pressure losses in automotive catalytic converters’ Proc. IMechE, Part C: J. Mechanical Engineering Science 223 C11 (2009): 2561–2569 DOI: 10.1243/09544062JMES1565.

10.

Wendland

D. W.

Matthes

W. R.

, ‘Visualisation of automotive catalytic converter internal flow’ (1986) SAE paper 861554.

11.

Kim

J. Y.

Lai

M.-C.

Chui

G. K.

, ‘Flow distribution and pressure drop in diffuser-monolith flows’ Trans. ASME, J. Fluids Eng. 117 (1995): 362–368.

12.

Shuai

S.-J.

Wang

J.-X.

Dong

Q.-L.

Zhuang

R.-J.

, ‘PIV measurement and numerical simulation of flows in automotive catalytic converters’ (2001) SAE paper 2001-01-3494 Also published in SP-1638 SAE International, Warrendale, PA, USA.

13.

Ilgner

Nau

Harndorf

Benninger

Schiessl

Maas

Dreizler

, ‘Analysis of flow patterns inside an autothermal gasoline reformer’ (2001) SAE paper 2001-01-1917.

14.

Quadri

S. S.

, The effect of oblique entry flow in automotive catalytic converters (2008) PhD Thesis.

15.

Melling

, ‘Tracer particles and seeding for particle image velocimetry’ Meas. Sci. Technol. 8 (1997): 1406–1416.

16.

Westerweel

, Digital particle image velocimtery, theory and application (1993) PhD Thesis.

17.

Marsters

G. F.

, ‘Spanwise velocity distributions in jets from rectangular slots’ AIAA J. 19 2 (1981): 148–152.

18.

Quinn

W. R.

, ‘Development of a large-aspect-ratio rectangular turbulent free jet’ AIAA J. 32 3 (1994): 547–554.

19.

Persoons

Vanierschot

Van den Bulck

, ‘Stereoscopic PIV measurements of swirling flow entering a catalyst substrate’ Exp. Therm. Fluid Sci. 32 (2008): 1590–1596.