Stagnation point flow configuration

A.ll experiments were conducted at atmospheric pressure in a quartz-glass flow tube reactor (2.-5 cm diameter. 20 cm length). The reaction gases were premixed and flowed perpendicular to the catalytic foil in a stagnation point flow configuration (inset fig. 1).. All experiments were conducted at total gas flow rates between 1 slpm and 6 slpm. which did not influence the results within experimental error. The high-purity platinum foils were resistively heated and the foil temperature was determined by a chromel/alumel thermocouple spotwelded to the back of the foil. Temperature measurements were reproducible within 10 K on the same foil and within 30 K in independent runs with different foils. 

Stagnation point flow configurations are common in heterogeneous kinetic studies. The flow of reactants issuing from a nozzle impinges on a catalyt-ically active surface positioned at a distance L from the nozzle exit. The stagnation point flow reduces mathematically, via the von Karman... 

Sheu, W.J. and Sivashinsky, G.L, Nonplanar flame configurations in stagnation point flow. Combust. Flame, 84, 221,1991. 

Figure 1 Experimental configuration (left) and flow field model (right) to study catalytic ignition of a stagnation point flow on a catalytic foil.

Compressible ID stagnation-point flow analysis forms the basis of the equation system presented below. It was found that the prediction of the effect of internal mass transfer limitations in the catalytic washcoat of the SFR configuration is crucial to derive microkinetic data from SFR experiments (Karadeniz, 2014 Karadeniz et al., 2013) our model is extended to include the diffusion limitations due to a porous layer. It should be noted that the CFiEMKIN code has no abihty to account for internal mass transport in the catalytic coating. 

Figure 2. Configuration used to test the boundary element equation against the exact Stokes solution. Surface one always has zero deformation. Surface tractions are specified on surfaces two, three and four. Tractions are calculated for simple shear and for stagnation point flow. Domain of Interest Is bounded.

Boundary-layer theory finds wide application in analyses of flame stabilization. The simplest configuration is the stagnation-point boundary layer, studies of which provide information concerning stabilization of a flame ahead of a bluff body placed in the flow some analyses and ideas... 

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