Nonstationary wave structure of intermittent supersonic jet

Naboko, I. M.; Белавин, В. А.; Golub, V. V.

doi:10.1016/b978-0-08-025442-5.50054-8

Cited by 2 publications

(2 citation statements)

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“…Upon sudden rupture of an overpressurized reservoir through an orifice, there is a transient evolution to the steady-state structure of an underexpanded jet, as examined in detail by Radulescu and Law [11], Lacerda [12], and Naboko et al [13], among others. The initial shock and the jet head both propagate outward and diffract, due to the area change.…”

Section: Introductionmentioning

confidence: 99%

Exhaust of Underexpanded Jets from Finite Reservoirs

Orescanin

Prisco

Austin

2010

40th Fluid Dynamics Conference and Exhibit

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The response of an underexpanded jet to a depleting finite reservoir is examined with experiments and simulations. An open-ended shock-tube facility with a variable reservoir length is used to obtain images of nitrogen-and heliumjet structures at successive instances during the blowdown from initial pressure ratios of up to 250. The reservoir and ambient pressures are simultaneously measured to obtain the instantaneous pressure ratio. We estimate the time scales for jet formation and reservoir depletion as a function of the specific heat ratio of the gas and the initial pressure ratio. The jet structure formation time scale is found to become approximately independent of the pressure ratio for ratios greater than 50. In the present work, no evidence of time dependence in the Mach disk shock location is observed for rates of pressure decrease associated with isentropic blowdown of a finite reservoir while the pressure ratio is greater than 15. The shock location in the finite-reservoir jet can be calculated from an existing empirical fit to infinite-reservoir jet data evaluated at the instantaneous reservoir pressure. For pressure ratios below 15, however, the present data deviate from a compilation of data for infinite-reservoir jets. A new fit is obtained to data in the lower-pressure regime. The self-similarity of the jet structure is quantified, and departure from similarity is noted to begin at pressure ratios lower than about 15, approximately the same ratio that limits existing empirical fits.

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Section: Introductionmentioning

confidence: 99%

Exhaust of Underexpanded Jets from Finite Reservoirs

Orescanin

Prisco

Austin

2010

40th Fluid Dynamics Conference and Exhibit

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“…The results of experimental study of the process of jet flow at the nonstationary stage are presented in [9][10][11][12][13][14][15][16][17]. An attempt to estimate analytically aspects of the evolution of the processes in the flow under transient directed ejections was undertaken by Chekmarev [18].…”

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confidence: 99%

The jet at the switch-on stage in a numerical and physical experiment

Bazarov¹,

Naboko²

1999

Comput Math Model

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We analyze the possibility of predicting the structure of the jet at the formative stage using a comparison of experimental results and computations carried out for flows beyond an acoustic nozzle. The correspondence of the computational model to the conditions in which the experiments were performed is discussed. It is shown that the question of the degree of reliability of the computational prediction should be decided on the basis of comparison of the approximation relations that describe the experimental and computational data.Introduction. State of the question. Among the wide circle of problems of gas dynamics questions involving a jet flow that is characterized by a complicated structure and is multiparameter occupy a special place. Stationary jets have been described quite thoroughly, but far from exhaustively [1,2]. It should be kept in mind, however, that a jet, that is, an ejection of gas with a certain set of parameters into a surrounding medium with other parameters has, as a rule a limited time of existence. The outflow can be regarded as stationary in the case when the total time of its realization is much larger than the time for the structure to become steady and for the distribution of parameters of the jet to become quasistationary. Here it is obvious that the stationarity of the parameters in these zones of flow depends on the coordinates and the time to reach steady state increases with distance from the nozzle slit and the axis of the jet. This is reflected qualitatively, for example, in the estimates given in [3]. The analytic solution of the problem involving the formation of a cylindrical symmetric jet (beyond a crack acoustic nozzle) leads to an infinite time to establish stationary parameters in the flow region M > 7 for outflow into a vacuum. The study carried out in [3] is tentative, but the result is logically consistent, since the filling of the surrounding medium with the outflowing gas determines the nonstationarity of the process on the boundary of the jet throughout the time of its existence. The time for the quasistationary parameters to become established near the nozzle slit is determined by the specific conditions under which the flow is realized. The study of the dynamics of nonstationary flow is motivated by the need to estimate the reliability of the prediction of the gas-dynamic and thermodynamic parameters of the flow when solving applied problems [4--6] and in carrying out studies in related areas of science, in particular in the study of the processes of intermolecular and intramolecular energy transfer, processes of clustering and condensation in flows, and characteristics of erosion burns arising as the result of pulse action on solid targets [7,8].The structure of a nonstationary forming jet differs fundamentally from the structure of a quasistationary steady flow. The results of experimental study of the process of jet flow at the nonstationary stage are presented in [9][10][11][12][13][14][15][16][17]. An attempt to estimate analytically aspects of the evolution ...

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Nonstationary wave structure of intermittent supersonic jet

Cited by 2 publications

References 0 publications

Exhaust of Underexpanded Jets from Finite Reservoirs

Exhaust of Underexpanded Jets from Finite Reservoirs

The jet at the switch-on stage in a numerical and physical experiment

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