1. The computationaleffort is divided into two parts. Thefust part dealswiththe demonstrationandvalidation process for the solution procedure by application to high speed turbulent reacting flowsinvolving finite rate hydrogen-air chemistry. As mentionedbefore,the Navier StokessolverTUFF hasbeen used forthe computations. Tworeacting flowconfigurations havebeen chosen for this part. The first test case considered is the BurroweKurkov experiment [23]. The flow configuration istwc-dimensional. A schematic diagramof the configuration is given in figure 1. Nwslip walls bound both the upper and lower regions (y=O and y=y,=). The lowerwallisinclinedtoforman expansion surface. Hydrogen is injected into a vitiated air stream. Thetwostreamsmixand react downstreamof the injection lourtion (inlet). The hydrogen stream is injected at a velocityof 1216m/sec and atemperature of 254 K. The airstream comesin at a speed of 1764 m/sec and a temperature of 1270K. Fulldetails about theflowparametersandgeometry aregiveninTable 2. In this case, the reference length used in the hydrogen jet width at inlet, h (h=0.004 m). A constant turbulence intensity level is used for arriving at the initial distribution of turbulent kinetic energy and the dissipation rate. A 13-step, &species HZ-Air reaction model(Table 1) hasbeen usedforthe finite-rate chemistry systemconsidered here. Thegridsize is 81X 121 (81grid points in the axial(5)direction and 121grid points in the transverse direction). The total length of the solution domain is 0.356 m (z/h=89). Available inlet data have been used for the firstplane pr+ files which improved the predictions remarkably over the solutions obtained with uniform profiles. The sw lutions are compared with the available experimental data at this location (exit) in figures 2-4. The solutions carried out with the space marching PNS code UPS [191using the Baldwin-Lomax turbulence model are alsogiven for comparison.
2. The second cae is that of coaxialjets [24,25]where a hydrogen jet flows (inner jet) coaxially with an outer vitiated air (massfractions: oxygen=0.246, wate0.209and nitrogen=0.545)jet. A schematicof the flow problem is given in Figure 5. The two streams are, air (Ir=1380 m/sec, T=1180 K with p=107000 N/m2) and hydrogen (U=1774 m/sec, T=545 K with p=112000 N/m2)., The air stream issupersonic with a Mach number of 1.97 and the hydrogen stream Mach number is 1.00. The inlet mean velocity is assumed to have a step profile with the twojets having uniform speeds at the specified values (no experimental data available). The velocity in the lip region of the inner jet tube wall (finite wall thickness) is assumed to be zero. The inlet temperature profile isderived based on the experimental data given for a location just downstream of it (shownlater). The inlet speciesmasfraction distributions are also chosen based on the experimental data provided at the same downstream location. The models for turbulence and chemistry are identical to the ones used for the first test case. A 81 X 91 grid (81 points in flow direction, 91 points in the radial direction) was used for the calculations. The inner jet/tube diameter (D=0.00236 m) is used as a reference length. The total length of the flowdomain is equal to 43.1 D. The outer boundary (radial) of the flow domain is taken to he at y=17 D. A more detailed description ofthe flow parameters is given in Table 3. The region outside the limitsof the airjet is assumed to be stillair at a temperature of 273 K. The two-equation (k-z) turbulence model is used along withthe finiterate HrAir chemistrymodelmentioned above. In all the figures shown for this case, y refers to the radial distance measured from the axis of the coaxial system ofjets.
3. Figures 6 - 7show the results of the computations. Figure 6 showsthe computed and experimentaldistributions of species mole fractions. The figure is designed in a two-column format. The left side column represents the inlet (first x-location) data and the right side column is the data at the exit plane (z/D=43.1 D). As seen in these figures, the inlet data agreementbetween the computationsand experiment is not perfect, especially around the jet edges, and this might affect the computed distributions at downstream locations. The comparison between predictions and experiment at the downstream location (z/D=43.1 D) isgood given the above mismatch between the computationaland experimental data at the inlet. The development of the reaction zone after ignition is not predicted well by the TUFF code whereas the SPARK code fares better. The experimental data indicates that the reaction zone (depicted by the water mole fraction distribution)spreads more quickly than the predictions indicate. There seems to be a discrepancy between the locations of peak reaction activity between the predictions (offthe axis) and the experiment (closer to axis). However, there is very good qualitativeagreementherween the data with the peak values of the reaction products predicted very well. Theflowdomainwasseen tohaveawavelikestructure asshown by the predicted profiles. Figure 7 showsthe comparisonofstatictemperaturedata. The agreement between predictions and experiment is good qualitatively diaplaying similar trends. The uncertainty associated with the accuracy of the experimental data is unknown. There are considerable differences between thedatapresented by the twoReferences [24,25], especially in the temperature profiles. Overall, there is good qualitativeagreementbetween the predictions and experiment.
4. In the second part, the turbulence-chemistry interaction model isdemonstrated using a two-dimensional mixing layer configuration. A schematic of the flow problem is given in figure 8. The two streams are, air (171606m/sec, T =1600 K with f=O.0,fo,=0.267 and f;=0.733)and hydrogen (U=1250 m/sec, T =254 K with f*=l.O, fo,=O.O and fiv,=O.O). The two streams are supersonic with the air stream Mach number of 2.07 and hydrogen stream Mach number of 1.03. The inlet mean velocity is assumed to have ahyperbolic tangent profile. A constant turbulence intensity level is used in the free stream for arriving at the initial distribution of turbulent kinetic energy and the specific dissipation rate. The pressures are matched between the two streams (P=1 atm.). A 13-step, &species HZ-Air reaction model (Table 1)hasbeen used for the finiterate chemistry system considered here. A 101X 81 grid (101 points in flowdirection, 81points in the transverse direction) was used for the calculations. The length of the flow domain is 0.25 m and its width is 0.05 m. In thefiguresthe titlegrefersto calculationsthat include the interaction model.