摘要:

By an extension of the ideas embodied in the single‐pulse shock tube, a technique has been developed which allows the direct measurement of recombination rates of many atomic species at high temperature. In the present technique, the expansion chamber is located a few tube diameters from the shock tube end plate rather than at the high‐pressure end as in the conventional single‐pulse shock tube. A cylindrical diaphragm, lying flush with the inside diameter of the tube, is used to control the time of initiation of an expansion wave. Experimental observation has shown that the present technique increases the gas expansion rate by an order of magnitude in comparison with the conventional single‐pulse shock tube. The one‐dimensionality of the flow at the shock tube end wall has also been investigated. The technique developed, in conjunction with the spectroscopic means of observation, was employed to gain preliminary measurements of the recombination rate of atomic chlorine.

ISSN:0031-9171    

DOI:10.1063/1.1706853

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A method is described for the solution of time‐dependent problems concerning the flow of viscous incompressible fluids in several space dimensions. The method is numerical, using a high‐speed computer for the solution of a finite‐difference approximation to the partial differential equations of motion. The application described here is to a study of the development of a vortex street behind a plate which has impulsively accelerated to constant speed in a channel of finite width; the Reynolds‐number range investigated was 15 ≤R≤ 6000. Particular attention was given to those features for which comparison could be made with experiments, namely, critical Reynolds number for vortex shedding, drag coefficient, Strouhal number, vortex configuration, and channel‐wall effects. The nature of the early stages of flow‐pattern development was also investigated.

ISSN:0031-9171    

DOI:10.1063/1.1706854

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A study of the effect of ionization on the stagnation‐point heat transfer to a noncatalytic wall is reported. The role of transport properties in heat‐transfer calculations and a comparison of currently available results are made. The applicability of using a nitrogen model for heat transfer in the ionization regime is discussed and comparisons with available air results are made. Correlation formulas for heat transfer in air and in nitrogen are presented

ISSN:0031-9171    

DOI:10.1063/1.1706855

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The effect of velocity slip and temperature jump on the heat transfer from a sphere in a low Reynolds number flow is investigated theoretically for large and small values of the Pe´clet number. A singular perturbation technique is used to obtain the small Pe´clet number solution while a boundary layer analysis is used to obtain the large Pe´clet number results. Expressions are derived for the average Nusselt number in each case. It is shown that for small Pe´clet numbers velocity slip can be neglected in the first approximation however this is not found to be the case for large Pe´clet numbers.

ISSN:0031-9171    

DOI:10.1063/1.1706856

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The slip coefficient is evaluated by a numerical quadrature using the exact analytical formula, which is obtained from the Gross‐Bhatnagar‐Krook model. The obtained valuez=1.1466(5)l, which is exact to the fourth decimal figure, is compared with the previous results.

ISSN:0031-9171    

DOI:10.1063/1.1706857

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The Chapman‐Jouguet detonation velocity and thermodynamic state variables are calculated for a representative set of CHON explosives, using the Lennard‐Jones and Devonshire cell theory equation of state together with a modified conformal solution treatment of the mixture problem, and allowing for chemical equilibrium among nine product species. Although fair agreement with experiment can be obtained by adjusting a single parameter of the pair potentials, the results are little better than those obtainable with much simpler theories.

ISSN:0031-9171    

DOI:10.1063/1.1706858

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The solutions of Wood and Adamson for steady state detonation wave structure are discussed with particular attention given to the hot boundary where combustion is complete. Unimolecular, irreversible reaction kinetics, with an ignition temperature, and small rate parameter are assumed. An alternate solution based on Wood's analysis is presented which agrees with Wood's and Adamson's results when the hot boundary Mach number is less than unity. The solution presented here does not agree with that of Wood when the hot boundary Mach number is unity. We find thatu∼ 1 + const (logx)−1asx→ 0 when the hot boundary Mach number is unity.uis the reduced velocity;xis the mass concentration of combustible.

ISSN:0031-9171    

DOI:10.1063/1.1706832

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Interferometric studies of low pressure laminar detonations have shown the existence of an induction zone with a maximum density in accord with that calculated for the shocked and vibrationally relaxed but unreacted initial mixture. In 2H2+ O2+ 2CO and 7H2+ O2the vibrational relaxation time is short compared to the induction time, and the latter time is in approximate agreement with the data of Schott and Kinsey. In H2+ 3O2the observations suggest that the vibrational relaxation time is comparable to, and may in fact determine, the induction time.

ISSN:0031-9171    

DOI:10.1063/1.1706833

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Under the assumption that the scalar field and the velocity field which transports it are both isotropic and Gaussian the small‐time behavior of the scalar transfer function can be obtained for any initial spectral distribution of turbulent energy and scalar ``energy.'' Specific spectra are calculated in detail and comparisons are made with work on the dynamics of isotropic turbulent fields. The effect of the relative scale of the energy containing regions of the velocity and scalar spectra is clarified. In particular wrinkling of a large scale scalar ``blob'' in a small scale turbulence field and the reverse phenomenon of stretching of a typical scalar ``blob'' when the scalar field has a characteristic size somewhat smaller than that of the velocity field are made evident.

ISSN:0031-9171    

DOI:10.1063/1.1706834

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

There are two effects giving rise to density corrections to the dilute gas transport coefficients. These are, (a) the corrections to the binary collisions due to their finite size and time of duration and (b) the triple collision effect. Neglecting the latter, expressions for the transport coefficients are well known and have been evaluated in the case of rigid spheres. These expressions for the transport coefficients are now simplified and evaluated approximately for inverse power potentials. The approximation consists in an expansion in inverse powers of the repulsion exponent a technique which has been shown by Baroody to give good agreement with exact calculations of the &OHgr; integrals.

ISSN:0031-9171    

DOI:10.1063/1.1706835

出版商:AIP    

年代:1963

数据来源: AIP