A study of pulsating flow in automotive catalyst systems

Benjamin, Stephen F.; Roberts, Carol A.; Wollin, J.

doi:10.1007/s00348-002-0481-0

Cited by 17 publications

(19 citation statements)

References 6 publications

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“…The reduction of the backward flow rate at the diffuser exit implies that the uniformity of the velocity distribution is high. The result wherein the flow uniformity increases with the pulsation frequency was also obtained in the experiment conducted by Benjamin et al [8], which was carried out at reasonably high frequencies for a 60° conical diffuser. Consequently, the time-averaged pressure rise increases, and the pressure loss decreases as the pulsation frequency increases.…”

Section: Estimate Of Backward Flow Ratesupporting

confidence: 68%

“…Benjamin et al [8], using a hot-wire anemometry, measured the distribution of a pulsating airflow within a system consisting of a section with divergence angles, 60° and 180°, and examined the effect of the pulsation on the flow uniformity. Moreover, King and Smith [9] and Mat Yamin et al [10] reported on the uniformity of distributions of the flow in a wide-angled planar diffuser and downstream of catalyst monoliths, where measurements were carried out under engine operating conditions using a hot-wire anemometry and a cycle-resolved particle image velocimetry, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…However, even in the studies of Benjamin et al [8] and Wang and coworkers [14,15] on conical diffusers, the velocity distributions for the diffusers were not provided, except for those at the inlet and exit planes. Therefore, studies that are more comprehensive are required.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Pulsating Turbulent Flow Through Diffusers

Sumida¹

2016

IJFMTS

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This paper presents the results of an experimental study on a pulsating turbulent flow through conical diffusers with total divergence angles (2θ) of 12°, 16°, and 24°, whose inlet and exit were connected to long straight pipes. To examine the effects of the divergence angle and the nondimensional frequency on flow characteristics, experiments were systematically conducted using a hot-wire anemometry and a pressure transducer. Moreover, the pressure rise between the inlet and the exit of the diffuser was analyzed approximately under the assumption of a quasi-steady flow and expressed in the form of simple empirical equations in terms of the time-mean value, the amplitude, and the phase difference from the flow rate variation. The expressions are in good agreement with the experimental results and very useful in practice. With the increase in the Womersley number, α, and 2θ, the sinusoidal change in the phase-averaged velocity, W, with time becomes distorted, and the W distributions show a more complicated behavior. For the flow at α=10 in the diffusers with large 2θ, the distributions of W are depressed on the diffuser axis. In contrast, for the flow at α=20, W has a protruding distribution on the diffuser axis.

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Section: Estimate Of Backward Flow Ratesupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Pulsating Turbulent Flow Through Diffusers

Sumida¹

2016

IJFMTS

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“…Figure 10 gives a comparison at equal engine speed and flow rate ( 100 m 3 /h) between the mean velocity on the CME (left) and isothermal (right) flow rig. The comparison is presented here since an isothermal flow rig approach is used by numerous authors [1,3,5,6,7] for studying pulsating flow in exhaust systems with close-coupled catalyst. The mean velocity fluctuations in Figs.…”

Section: Helmholtz Resonancesmentioning

confidence: 99%

“…where  = density [kg/m 3 ], p = pressure [Pa], V = cylinder volume [m 3 ] , T = temperature [K] and the subscripts i, e, 0 respectively denote intake valve closing, exhaust valve opening and top dead centre. The adiabatic temperature rise due to combustion equals…”

mentioning

confidence: 99%

Experimental study of flow dynamics in close-coupled catalyst manifolds

Persoons

Hoefnagels

Bulck

2007

International Journal of Engine Research

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Time-resolved flow dynamics in an automotive exhaust manifold with closecoupled catalyst are investigated experimentally on a charged motored engine (CME) flow rig. Flow similarity between CME and fired engine conditions is discussed analytically. Oscillating hot-wire anemometry (OHW) is used to measure the bidirectional phase-locked velocity. Strong time-resolved mean catalyst velocity fluctuations are observed. These are analysed as Helmholtz resonances, using a one-dimensional gas dynamic model of the manifold. The spatial and temporal occurrence of instantaneous reverse flow in the catalyst is investigated, for varying engine load conditions. Periodic backflow occurs throughout large portions of the catalyst cross-section, and proves to be strongly linked to the observed Helmholtz resonances.

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Study of pulsating flow in close-coupled catalyst manifolds using phase-locked hot-wire anemometry

Persoons

Bulck

Fausto³

2004

Experiments in Fluids

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Phase-locked sampling has been applied to hot-wire anemometry in order to investigate the pulsating flow inside two types of automotive exhaust manifolds fitted with a close-coupled catalyst. An isothermal dynamic flow bench has been used to compare the catalyst velocity distribution in steady operation to crank angle resolved velocity distributions measured in pulsating flow. The latter were obtained using phase-locked averaging. A rotating valve and a cylinder head have been used to generate the pulsating flow. Experimental results have proven the addition principle, i.e. the time-averaged velocity distribution in pulsating flow is proportional to a specific linear combination of velocity distributions, resulting from steady flow through each runner.

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A study of pulsating flow in automotive catalyst systems

Cited by 17 publications

References 6 publications

Experimental Investigation of Pulsating Turbulent Flow Through Diffusers

Experimental Investigation of Pulsating Turbulent Flow Through Diffusers

Experimental study of flow dynamics in close-coupled catalyst manifolds

Study of pulsating flow in close-coupled catalyst manifolds using phase-locked hot-wire anemometry

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