Solid-Fuel Rocket Motor Efficiency Improvement Scheme - Novel Combustion Concepts for Sustainable Energy Development - page 543

Fig. 18 Boundary length of
three models with V air =40m/
s (Amano et al. 2014a , b )

14.00

13.00 ±0.61

±0.40

12.00

±0.41

11.00

10.00

9.00

8.00

7.00

6.00

11.85 12.79 12.87

5.00

k- ʵ SST k- ˉ RSM

Turbulence Models

Figure 19 shows the superposition of VF with the three turbulence model and
result from experiment. The k- model shows the least thick breakup band at the

region downstream from the ramp. The SST k-

ε

has a relatively uniformly distrib-
uted breakup band downstream of the ramp and this explains why the SST k-

ˉ

model
produced a less standard deviation of boundary length due to lower unsteady breakup
phenomenon. A wider and darker band downstream of the ramp is seen in the case of
the RSM model, which could be interpreted as a more uniform breakup process
occurring around region (i). The superposition of experimental images does not show
the probability distribution clearly due to the nonuniform distributed light source;
however, the pro

ˉ

le of the two-phase boundary in the ramp vicinity is similar to

RSM ' s pro le.

Fig. 19 Result of
superposition of different
turbulence models and
experiments, V air = 40 m/s
(Amano et al. 2014a , b )

k- ʵ

SST k- ˉ

RSM

( i )

Experiment