Stereoscopic PIV measurements of swirling flow entering a catalyst substrate

Abstract

a b s t r a c tThis experimental study investigates the stagnation region of a swirling flow entering an automotive catalyst substrate. A methodology is established using stereoscopic particle image velocimetry (PIV) to determine three-component velocity distributions up to 0.2 mm from the catalyst entrance face. In adverse conditions of strong out-of-plane velocity, PIV operating parameters are adjusted for maximum spatial correlation strength. The measurement distance to the catalyst is sufficiently small to observe radial flow spreading. A scaling analysis of the stagnation flow region provides a model for the flow uniformization as a function of the catalyst pressure drop.

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

“…9. This observation is consistent with the findings of Persoons et al [19], who measured velocities up to 0.3 mm from the inlet of a monolith presented with swirling flow. They showed a significant swirl component even at such close proximity to the monolith.…”

Oblique inlet pressure loss for swirling flow entering a catalyst substrate

“…In the vicinity of the inlet face, LDA signal quality rapidly deteriorates due to wall reflections. Therefore, stereoscopic particle image velocimetry (PIV) is used in a follow-up paper [21] to examine the axial, tangential and radial velocity closer to the inlet face For positive swirl, the additional pressure loss due to oblique flow entry is correlated to the peak tangential velocity upstream of the substrate. Although there is evidence of radial velocity near the inlet face, the tangential velocity is not significantly affected.…”

“…where This effect could not be adequately measured with LDA. Instead, stereoscopic PIV is used in a follow-up study [21] to investigate the flow stagnation region.…”

Experimental verification of hydrodynamic similarity in hot flows

“…In the case of a hot end, which includes a catalytic converter with its monolith, the small section of the passages in the monolith bundle should give rise to a dependence that includes, together with the quadratic term associated with turbulent losses at the inlet and the outlet of the monolith, a linear term representing the laminar pressure drop across the monolith itself [11,12]. The total resulting pressure drop can be expressed thus as:…”