Dynamic Motion of Rotating Bunsen Flame Tip in Microgravity

Abstract

Fig. 4 Comparison of the velocity profile parameters with the separation correlations. Fig. 5 Mean velocity distributions compared with Eq. (1).The point of zero-mean surface shear stress separation, τ w = 0, is more of academic interest, although it plays an important role in the development of skin-friction relations 4 and empirical velocity profile representation.The Sandborn-Kline 5 τ w = 0 correlation was obtained by employing an empirical laminar velocity separation profile, 6(1) Figure 5 shows a comparison of the TAD velocity profile at 170 deg and Re = 5 × 10 5 with Eq. (1) for the case m = 4. Equation (1) is also compared with the 170-deg, Re = 2 × 10 5 data in Fig. 2. It was assumed that the normal coordinate n was equivalent to y. The profile (Fig. 5) is beyond the point of τ w = 0; however, the agreement with Eq. (1) for the outer region of the profile τ w = 0 is reasonable. The tabulated law of the wake function, 7 which is found to be one unique case of Eq. (1) for m = 2.1, is also shown in Fig. 5. The value of δ for the law of the wake was taken at the point where U/U e = 0.995, which is consistent with the requirements of the measured profiles. 4 Equation (1) can be employed for a wide range of flows and is not limited to large aerodynamic flows. ConclusionsThe velocity distribution in a complex, small radius of curvature, TAD shear flow was shown to follow closely the separation model developed for canonical, two-dimensional, large-Reynolds-number, turbulent boundary layers. The TAD flow produces a very thin shear layer along the inner surface of the initial 90 deg of the turn. Beyond 90 deg, the inner wall shear layer thickens and develops to the start of separation by approximately 150 deg around the turn. The shear layer velocity shape parameters are found to develop through the separation region as predicted by the Sandborn-Kline separation model.The mean velocity distributions in the region of zero-mean surface shear stress separation were shown to agree with equivalent laminar separation profiles.

Orbital instability and prediction of a Bunsen flame tip motion with burner rotation

“…This result elucidates that the periodic oscillation is due to buoyancydominated instability, while the nonperiodic oscillation is not induced by buoyancy force. The nonperiodic oscillation is supposed to be induced by the hydrodynamic effect due to the combination of jet inertial force and centrifugal force [31]. Although at the present stage of our research we have yet to address in detail how the velocity field interacts with the route to the chaotic mode, these results suggest that the growth of hydrodynamic perturbation that is inherently included in the approaching flow results in the phase randomness in the flame motion.…”