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The rotational-translational energy transfer in collisions between homonuclear diatomic molecules and the rotational relaxation time in diatomic gases have been investigated classically. Using Parker's model for the intermolecular potential, numerical solutions were obtained for the rotational-energy transfer in individual collisions. The method of solution for the collision trajectories has been combined with a Monte Carlo integration procedure to evaluate the transport properties for diatomic gases. The formal kinetic-theory expressions derived by Wang Chang, Uhlenbeck, and Taxman for the transport coefficients of gases with internal energy states were used. Results are presented for the shear viscosity, thermal conductivity, and rotational relaxation time in N2 which compare favorably with experimental values. Results are included for both a coplanar and three-dimensional collision model. Approximate solutions for the rotational-energy transfer in coplanar collisions and the rotational relaxation time are also presented. The approximate expression for the relaxation time agrees well with the Monte Carlo calculation and with experimental data for N2 and O2. The effect of unequal rotational and translational temperatures was also studied and found to be significant.

This paper reports the results of a study on multi-recompression heating. This process employs a Roots-type mechanism to heat gases to very high temperatures by compressive gas heating. A CFD model predicting the leakage flows in the machine was developed, and an excellent comparison with experimental data taken on a two-lobe Roots blower was obtained. A "clearance analysis" was performed to show that the clearance between the impellers remains constant for 96% of the angles of rotation. Assuming a quasi-steady state, the CFD simulation was performed for a single angle of rotation. A three-dimensional analysis showed that the flow field is identical along the rotor length, except for the leakage through the end plates. Hence, the model was further simplified to a two-dimensional analysis. This research may provide guidance in predicting the leakage flows in other blowers of the same kind with a different geometry.

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Linearized solutions for the flow field of a rotating blade row in an infinitely long annular duct are reviewed. An isolated rotor is assumed to operate in a uniform axial flow so that the disturbance field is steady in a blade fixed co-ordinate system. Both three-dimensional and compressibility effects are included, but attention is confined to subsonic flows. Previously published source-flow solutions omitted a term which affected the thickness part of the rotor flow field constructed from them. Corrected source and rotor-thickness solutions are given, and then the source or monopole solution is used to form a pressure dipole solution. The rotor-loading contribution to the flow field is found by superposition of the revised dipole solutions. The present version of the dipole representation of the steady-loading field is shown to be equivalent to an existing vortex representation, but different from an existing dipole representation. The behaviour of the blade-surface pressure and velocity distributions is described for both the thickness and loading cases. Sample numerical evaluations of the surface quantities are presented.

idea of the range of applicability of Cohen's solution, the percentage error in / + [from his Eq. (19)] as a function of r P * for constant values of K is given in Fig. 8.Cicerone and Bowhill obtain numerical solutions for the attracted ion distribution at large probe potential and the corresponding probe characteristics. The characteristics presented, covering a range of .1 < p p < I and an approximate potential range of 20 < & p * < 500, agree with the current results in the overlapping potential range, at least to within the accuracy attainable in reading the plotted data. ConclusionsNumerical solutions of the spherical continuum electrostatic probe equations have been obtained for the case of equal electron and ion temperatures for a wide range of probe radius to Debye length ratio. Since the exact numerical solutions of the complete equations are straightforward and economical to obtain (in the range 15 to 25 seconds per solution on a CDC 6500 computer), it appears that further investigations of these equations should be aimed at finding simplified solutions of closed form. The numerical results presented here should prove valuable in assessing the accuracy of any such solutions.Thin-wire Langmuir probes aligned with the flow direction have been used to measure the electron temperature and electron density in the inviscid nozzle flow of a short-duration reflected-shock tunnel. The electron density was inferred from the ion current portion of the probe characteristic and was simultaneously measured using microwave interferometers. The test gas used in these experiments was nitrogen at an equilibrium reservoir condition of 7200°K and 17.1 atm. At selected nozzle locations, the probe diameter and fineness ratio (L/D) of the probe were systematically varied in order to investigate probe performance in the transition and free-molecular flow regimes. The measured electron temperatures did not depend upon the probe diameter or the fineness ratio. The electron density inferred from the probe characteristic was found to be sensitive to collisional effects but insensitive to the fineness ratio in both the transition and free-molecular flow regimes. For free-molecular flow the results agree with Laframboise's theoretical predictions for ion collection in a portion of the orbital-motion-limited region. For probes having a radius less than a debye length in a freemolecular flow, the experimental results appear to disagree with the theory, the collected currents being larger than those predicted. In the transition-flow regime, the correction for collisional effects given by Talbot and Chou provides good agreement between the Langmuirprobe and microwave-interferometer electron-density data.

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