Some singularities of supersonic underexpanded jet interaction with a plane obstacle

Results are presented of an experimental investigation of the interaction between a supersonic underexpanded jet and an obstacle mounted at various distances from the nozzle exit. It is shown that for certain distances h unstable modes of flow around the obstacle are observed for Ma=2.18, n=1.9, 3.6相似文献   

Determination of the parameters of a supersonic gas jet impinging on an inclined flat obstacle

Results are given of a theoretical and experimental investigation of the interaction of a supersonic gas jet issuing from a conical nozzle with an inclined flat obstacle. Relations have been obtained for determining the boundaries of the spreading of the stream around the obstacle and the gasdynamic parameters. The results of the computation are confirmed by experiment.     

Features of the interaction of a supersonic off-design jet with a barrier of finite dimensions

This article examines the qualitative pattern of flow in the interaction of an off-design jet with a barrier. A criterion for unstable flow about the barrier is presumed to exist.Translated from Inzhenerno-Fizieheskii Zhurnal, Vol. 46, No. 3, pp. 375–380, March, 1984.     

Optical electron-beam diagnostics of free supersonic jet of nitrogen activated by electron-beam-generated plasma

Electron-beam-induced optical emission spectroscopy has been used for the first time to measure the rotational temperature and number density of gas in a free supersonic neutral nitrogen jet and in that activated by electron-beam plasma. The electron-beam plasma was generated by a low-energy electron beam at a distance of 10 mm downstream from the edge of a conical supersonic nozzle. For diagnostics of the activated jet, the spectrum of intrinsic optical emission of plasma was subtracted from the spectrum of emission induced by the probing electron beam in the activated jet. It was established that the rotational temperature in the activated jet is increased as compared to that in the neutral jet, while the density at the jet axis is decreased. The electron-beam activation of nitrogen in the jet leads to a 35% increase in the rotational temperature.     

Nanocrystalline silicon carbon doped films prepared by hot wire technique

In this work we present data concerning the structure, composition and electro-optical performances of nanocrystalline silicon carbide doped films produced at the different filament temperatures and hydrogen dilution ratios. The XRD spectra reveal the presence of the typical Si peaks ascribed to (111) (220) and (311) diffraction planes, where no traces of the carbon peaks were found. The average grain sizes ranges from 10 nm to 30 nm, depending on the temperature of filament and hydrogen dilution used. We observed an enhaneement of the peak ascribed to the (220) plane when high H dilution rates are used, meaning that the film starts being textured. The infrared data reveal the typical silicon carbide modes and a hydrogen content that varies from 3% to 1%, with the increase of the filament temperature. Besides that, the IR spectra show the typical SiO₂ and SiO modes, associated to the oxide species that are mainly incorporated in the surface of the films and can be removed by proper wet etching. The planar conductivity is enhanced as the temperature of the filament is increased, being the highest conductivity achieved in the range of 0.2 (Ωcm)⁻¹ and almost non activated.     

The effect of arbitrarily oriented hot jet on supersonic flow past a blunt body

We present the results of numerical simulations of the flow past a blunt body, from which an oriented thin hot jet of an ideal gas is emitted. The dependences of the flow regime and total aerodynamic characteristics of the blunt body on the angle of hot jet emission have been studied.     

Mass addition of a supersonic jet

Presented are results of an experimental determination of the mass addition for a supersonic jet in flow regimes with n = P_ch/P_a 1. An empirical formula is given relating the mass addition in the initial section to the Mach number M _a at the nozzle exit, the ratio n, and the distance from the nozzle exit section to the section examined.     

The interaction between plasma jet of a capillary discharge and transverse supersonic air flow

An experimental investigation is performed of modes of outflow into stationary air and of supersonic flow of a plasma jet developed by a capillary plasma generator. A theoretical model is suggested, which explains the obtained experimental results and enables one to simulate the process of injection of plasma jet into a supersonic air flow. The possibility is demonstrated of using such jets for the ignition of supersonic flows of combustible mixture.     

Study of the interaction between a hot gas jet and a liquid bath

Results are presented from an experimental investigation of the interaction between a hot gas jet and a liquid bath with different schemes of organization of the jet.     

Microstructures of microcrystalline silicon thin films prepared by hot wire chemical vapor deposition

Undoped hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared at low temperature by hot wire chemical vapor deposition (HWCVD). Microstructures of the μc-Si:H films with different H₂/SiH₄ ratios and deposition pressures have been characterized by infrared spectroscopy X-ray diffraction (XRD), Raman scattering, Fourier transform (FTIR), cross-sectional transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The crystallization of silicon thin film was enhanced by hydrogen dilution and deposition pressure. The TEM result shows the columnar growth of μc-Si:H thin films. An initial microcrystalline Si layer on the glass substrate, instead of the amorphous layer commonly observed in plasma enhanced chemical vapor deposition (PECVD), was observed from TEM and backside incident Raman spectra. The SAXS data indicate an enhancement of the mass density of μc-Si:H films by hydrogen dilution. Finally, combining the FTIR data with the SAXS experiment suggests that the Si---H bonds in μc-Si:H and in polycrystalline Si thin films are located at the grain boundaries.     

Unsteady-state heat transfer in the region of interaction between a turbulent jet and an obstacle

Unsteady-state heat transfer is considered in the region of interaction between a round turbulent jet and a normally positioned flat obstacle. The Navier-Stokes equations filtered over space are closed by the RNG-model of eddy viscosity which takes into account the curvature of the lines of flow in the region of turning of flow. The calculations are performed for different relative distances from the nozzle exit section to the obstacle and for different values of Reynolds number. The correlation between the distribution of characteristics of heat transfer over the obstacle surface and the eddy structure of the jet is discussed.     

Performances of a-Si:H films produced by hot wire plasma assisted technique

This work reports on the performances of undoped and doped amorphous/nanocrystalline silicon films grown by hot wire plasma assisted technique. The structure (including the presence of several nanoparticles with sizes ranging from 5 nm to 50 nm), composition (oxygen and hydrogen content) and transport properties of the films are highly dependent on the temperature of the filament and on the hydrogen dilution. The undoped films grown under low r.f. power (≈4 mWcm⁻²) and filament temperatures around 1850 K present dark conductivities below 10⁻¹⁰ Scm⁻¹, optical gaps of about 1.6 eV and photosensitivities above 10⁵, (under AM1.5 light intensities), with almost no traces of oxygen content. For the n- and the p-doped silicon films also fabricated under the same conditions the conductivities obtained are of about 10⁻² Scm⁻¹ and 10⁻⁵ Scm⁻¹, respectively.     

Effect of the electric discharge on nonstationary processes during supersonic air and methane jet flow over a flat obstacle

The features of supersonic air and methane jet flows over a flat obstacle, accompanied by an electric discharge, were studied. The flow under consideration is characterized by a number of unsteady effects appearing as oscillations of shock-wave fronts with various amplitudes and frequencies depending on the nozzle-obstacle system configuration and jet gas-dynamic parameters. The oscillation frequency of the bow shock wave increases as the obstacle becomes closer to the nozzle edge and the relative obstacle diameter and the supersonic jet stagnation pressure increase. Initiation of the energy release region at the supersonic jet edge causes a change in the oscillation frequency of the bow shock wave; under certain conditions, it causes a change in the entire shock-wave flow pattern.     

Wave structure of a supersonic jet discharging into an opposing supersonic stream

A similarity parameter is suggested for the longitudinal dimensions of the wave structure of a supersonic underexpanded jet discharging into an opposing supersonic stream, and empirical equations are obtained for the calculation of these dimensions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 4, pp. 672–676, October, 1978.     

Experimental study of a submerged supersonic two-phase jet

An optical-laser method was used to measure the size and concentration of liquid drops in a supersonic gas-drop jet.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 3, pp. 379–383, September, 1988.     

Experimental investigation of the interaction between the plasma of an electrically exploded wire and a plane obstacle

The results of an investigation of the physical processes that occur when pulses of dense low-temperature plasma, generated by electrical explosion of a wire, flow over a plane dielectric obstacle are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 5, pp. 813–819, May, 1984.     

Possibility of cleaning a channel in a snowy atmosphere by a supersonic off-design jet

It has been found that the threshold value of the product of the excess gas pressure in the forechamber by the area of the nozzle throat is responsible for the appearance of the cleanup effect for a fixed nozzle-photodetector distance. The thermodynamic and dynamic criteria for the occurrence of the cleanup of the laser-beam trajectory have been formulated. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 165–170, January–February, 2008.     

Peculiarities of flow over a blunted body by a supersonic polydispersed jet with a swirl of reflected particles

The acceleration of monodispersed and polydispersed axisymmetric nozzle flows and their interaction with a sphere are investigated. The formulas given in [1] are applied to the recovery coefficients of velocity components of reflected particles. For the development of a physicomathematical model, semiempirical information on the influence of particle rotation on coefficients of its interaction with a carrier continuous medium, the Magnus force, and the damping torque are taken into account. Numerical investigations are carried out for a characteristic mass spectrum of particles as a set of several fractions [2]. It is demonstrated that the rotation of monodispersed particles leads to the caustic (envelope of paths of reflected particles) moving away from the body in the flow. The algorithm elaborated enables specific details of the mass spectrum of the particles bombarding the body with known thermomechanical properties and coefficients of their interaction with the body surface to be estimated by comparing experimental and numerical results.     

Influence of stream vorticity on friction and heat exchange in application to the case of a supersonic jet impinging on an obstacle

The flow in the neighborhood of the stagnation point of a stationary plane stream of viscous incompressible fluid with harmonic components superposed on the velocity components is investigated. Such a flow corresponds to a stream containing periodic eddies perpendicular to the flow plane. The results of the investigation can be applied to estimate thermal fluxes.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 4, pp. 633–638, October 1969.