Trace development behind a pulsed-periodic energy source

A two-dimensional nonstationary problem of the trace development behind a pulsed-periodic energy source occurring in a supersonic flow is considered.     

Kerosene Combustion in a Pseudoshock with Varied Conditions at the Supersonic Ramjet Combustor Model

Combustion, Explosion, and Shock Waves - Results of studying kerosene combustion in a pseudoshock with varied temperature and velocity in a supersonic ramjet combustor model are presented....     

Effect of laser radiation and electric field on combustion of hydrocarbon-air mixtures

Publications on combustion of hydrocarbon-air mixtures under the action of a weak electric field and laser radiation are analyzed. A specific feature of the authors’ experimental study is a pulsed-periodic action of an electric field and focused laser radiation, which does not lead to electric discharge or optical breakdown. Numerous experiments reveal a noticeable effect of weak electric fields on combustion processes. Application of an electric field may result in expansion of the limits of flammability and combustion of fuel-air mixtures, changes (decrease or increase) in the burning rate, shifting of flame stabilization toward lean mixtures, reduction of the concentration of hazardous substances (for instance, NO _x and CO) in combustion products, etc. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 77–85, July–August, 2009.     

Combustion initiation by an optical discharge in a supersonic methane-air jet

The first experimental studies of the effect of the laser plasma generated by focused pulsed-periodic radiation of a CO₂ laser on the formation and evolution of combustion in a supersonic flow of homogeneous methane-air mixtures are performed. Results of multispectral investigations testify to a principal possibility of combustion initiation by an optical discharge. Conditions necessary for combustion stabilization are formulated.     

Influence of a periodic pulsed energy source on the regime of supersonic flow past a body

A two-dimensional nonstationary problem on the interaction of a trace developed behind a periodic pulsed energy source and a body occurring in a supersonic flow is considered. The results of numerical calculations are compared to the available experimental data.     

Problems of development of a mobile system of remote energy supply of small unmanned aerial vehicles by microwave radiation

Methods and systems of remote energy supply of unmanned aerial vehicles (UAVs) are reviewed. It is expedient to use microwave radiation for efficient energy supply of UAVs at distances of several hundred meters. It is shown that energy transfer with the use of microwave radiation is realizable for recharging of UAVs at distances of about 100 m with an efficiency of 50–80%. It is demonstrated that main difficulties in implementation the UAV remote energy supply systems is associated with the lack of Schottky-barrier microwave rectifying diodes, reduction of the mass and overall dimensions of the receiving antenna, hardware and software efficiency increase methods, and methods for ensuring the electromagnetic compatibility.     

Interaction of shock wave with subsonic heated layer

The problem of attenuation of an incident shock wave on the passage through a heated layer of finite thickness has been considered by numerical methods. Three possible regimes of interaction of the incident shock wave with the heated layer are revealed. It is shown that a significant decrease in intensity of the incident shock wave is caused by its interaction with a heated subsonic jet trace.     

Spectral characteristics of optical discharge in a high-speed methane–air jet

Results of gasdynamic and spectroscopic investigations of optical discharge in the subsupersonic flow of a homogeneous fuel–air (CH₄ + air) mixtures are presented. The combustion was initiated and maintained by optical discharge created using a CO₂ laser. The laser radiation propagated across the flow and was focused by a lens on the axis of the supersonic jet (M = 2). Emission-spectroscopy techniques provided data on the composition of radiating combustion products and the intensity of components emitted in the region of optical discharge. Patterns of Toepler’s visualization of the flow structure in the schlieren scheme are presented. The images were monitored by a high-speed video camera operating at an exposure time of 1.5 μs and a frame frequency of 1000 s^–1.     

Cyclotron Resonance of Electrons and Holes in Paramagnetic and Ferromagnetic InMnAs-Based Films and Heterostructures

We have studied the cyclotron resonance of electrons and holes in various types of InMnAs-based structures at ultrahigh magnetic fields. Our observations, in conjunction with an eight-band effective mass model including the s–d and p–d exchange interactions with Mn d-electrons, unambiguously suggest the existence of s-like and p-like delocalized carriers in all samples studied. The samples studied include Paramagnetic n-type In_1–x Mn _x As films (x 0.12) grown on GaAs, ferromagnetic p-type In_1–x Mn _x As films (x 0.025) grown on GaAs with Curie temperatures (T _C) > 5 K, paramagnetic n-type In_1–x Mn _x As/InAs superlattices, ferromagnetic p-type In_1–x Mn _x As/GaSb heterostructures (x 0.09) with T _C = 30-60 K, and ferromagnetic (In_0.53Ga_0.47)_1–x Mn _x As/In_0.53Ga_0.47As heterostructures (x 0.05) grown on InP with T _C up to 120 K.