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991.
In this paper, the theoretical studies of stress concentrations in the compressor blades of aircraft gas turbine engines damaged
due to foreign objects ingestion into the gas-air flow path are presented. The technique of three-dimensional finite-element
calculations of the theoretical stress concentration factor in the damage region has been developed. We also examined the
influence of geometrical blade parameters and damages (stress concentrators) upon the theoretical concentration factor and
suggest using a simple relation for its approximate assessment. 相似文献
992.
A two-front model of turbulent combustion is presented, which makes it possible to describe the processes taking place in
diffusive and homogeneous flame fronts, as well as to take into account the influence of various factors that cause flame
front destabilization. The model is based on the use of equation for the extent of reaction (combustion completeness). In
the paper, the model applied to the combined analysis of combustion chamber is considered, that is, to assessment of the NO
emission level and flame front stabilization limits. 相似文献
993.
V. N. Tarasov 《Russian Aeronautics (Iz VUZ)》2011,54(1):29-33
Peculiarities of gas flow through the impulse turbine stage duct are discussed when a gas distribution mechanism is mounted
behind the turbine. A technique of calculating the characteristics of such a stage based on the experimental study results
and some calculation results are presented. 相似文献
994.
A manufacturing process for the wedge-shaped folded core of the M-crimp type is considered. Also presented is the parametrical
simulation model of the cutting head; the model was constructed by using the Solid Works 2009 CADS software and is meant for
automatic change of core geometry in cases when one or several initial parameters are varied. 相似文献
995.
996.
D. S. Guzachev D. V. Kratirov V. A. Zorin N. I. Mikheev 《Russian Aeronautics (Iz VUZ)》2011,54(2):141-145
The method of analyzing the small-size rocket liftoff is presented. Under consideration is a system that consists of a rocket
with an operating rocket engine, a launch tube, and an operating gas generator mounted in the tube under the rocket. The liftoff
parameters including the rocket motion velocity inside the tube and the loads applied are calculated. The calculated and experimental
data were compared and their adequate agreement is presented with respect both dynamics of rocket impulse-reaction liftoff
from the launch tube and the launch velocity. 相似文献
997.
In this paper, a decrease of turbulent pulsations of velocity in a boundary layer and the coefficient of friction drag for
an accelerating flow on the perforated surface with blind damping cavities is experimentally found. We generalize the mathematical
model of partial boundary layer laminarization [1], which is based on the experimental data [2, 3] obtained earlier on a decrease
of the friction drag coefficient and deformation of average velocity profiles in the stabilized section of flow in the perforated
tube with blind damping cavities. 相似文献
998.
E.E. Antonova N.O. Ermakova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
The problem of auroral particle acceleration is analyzed taking into account the filling of the magnetosphere by accelerated particles of ionospheric origin and the trapping of particles between the magnetic and electrostatic barriers. It is taken into account that kappa distributions describe experimentally measured distribution functions better than do maxwellians. The existence of conjugate field-aligned potential drops in the north and south hemispheres is suggested. Field-aligned potential drops are formed if the value of field-aligned current is higher than the threshold determined by the free gazodynamic flow of electrons along field lines. Results of experimental observations showing the possibility of field-aligned potential drop concentration in double layers are summarized. The theory of kinetic double layers is developed taking into account the nonmaxwellian forms of distribution functions. It is shown that the kinetic treatment and the existence of nonmaxwellian distributions lead to real changes in the criteria required for double-layer formation. 相似文献
999.
O Monje G E Bingham J G Carman W F Campbell F B Salisbury B K Eames V Sytchev M A Levinskikh I Podolsky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,26(2):303-306
The SVET Greenhouse on-board the Orbital Station Mir was used to measure canopy photosynthesis and transpiration rates for the first time in space. During the Greenhouse IIB experiment on Mir (June-January 1997), carbon and water vapor fluxes from two wheat (cv. Superdwarf) canopies were measured using the US developed Gas Exchange Measurement System (GEMS). Gas analyzers capable of resolving CO2 concentration differences of 5 micromoles mol-1 against a background of 0.9% CO2, are necessary to measure photosynthetic and respiratory rates on Mir. The ability of the GEMS gas analyzers to measure these CO2 concentration differences was determined during extensive ground calibrations. Similarly, the sensitivity of the analyzers to water vapor was sufficient to accurately measure canopy evapotranspiration. Evapotranspiration, which accounted for over 90% of the water added to the root zone, was estimated using gas exchange and used to estimate substrate moisture content. This paper presents canopy photosynthesis and transpiration data during the peak vegetative phase of development in microgravity. 相似文献
1000.
Gray W.S. Gonzalez O.R. Dogan M. 《IEEE transactions on aerospace and electronic systems》2000,36(4):1204-1218
High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. Such upsets can degrade the quality of the control signal ranging from a perturbation error over a few sample periods to a permanent error mode or computer failure. Under these conditions, the primary concern of the control engineer is to insure that the closed-loop system remains stable. A stochastic disturbance model and a set of associated stability assessment tools are introduced for determining stability robustness of a nominal closed-loop system subject to electromagnetic disturbances. The focus is primarily on night control applications, but the methodology is suitable for any application where highly reliable digital control is needed. The technique is demonstrated on a simple test example and on a stabilizing controller for the longitudinal dynamics of the AFTI/F-16 aircraft. 相似文献