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1.
V. M. Fomin V. F. Chirkashenko V. F. Volkov A. M. Kharitonov 《Journal of Applied Mechanics and Technical Physics》2008,49(6):962-970
The possibility of controlling the sonic boom level by means of cooling the surface of a flying vehicle is discussed. The
effect of surface cooling on the formation of the perturbed flow structure at large distances from the vehicle is demonstrated
by an example of a modified power-law body of revolution. The intensity of the intermediate shock wave and the perturbed pressure
pulse near the body are seen to decrease, which expands the altitude range of the region where the sonic boom is reduced (down
to 50%). At larger distances from the body, cryogenic forcing ensures a 12% decrease in the bow shock wave intensity. The possibility of controlling the process of formation of wave structures near
the surface, such as barrel shock waves, is demonstrated. An explanation of the cryogenic forcing mechanism is offered.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 88–98, November–December, 2008. 相似文献
2.
V. M. Fomin V. F. Chirkashenko V. F. Volkov A. M. Kharitonov 《Journal of Applied Mechanics and Technical Physics》2011,52(3):397-405
The influence of the basic factors of cryogenic forcing on formation of the middle zone on the sonic boom and aerodynamic
characteristics of the flying vehicle is studied by experimental and numerical methods. Experimental data obtained with alcohol
or liquid nitrogen as an injected liquid are used for comparisons; as a result, the total effect of temperature and coolant
evaporation can be determined. The influence of temperature is studied by means of numerical simulations of the cryogenic
action of distributed injection of air. A comparison of numerical and experimental data reveals the effect of the coolant
evaporation process on perturbed flow formation. It is demonstrated that evaporation of the coolant outgoing onto the vehicle
surface should be intensified to increase the efficiency of cryogenic forcing (to decrease the coolant flow rate). 相似文献
3.
A numerical study of the possibility of reducing the sonic boom level in the case of local heat release to a supersonic gas flow at Mach number equal to 2 ahead of a body is described. The computations are performed for a spherical heat supply zone located on the flight trajectory ahead of the tip of an axisymmetric thin body. For the numerical study the combined method of “phantom bodies” is used. Different magnitudes of heat supply to the incoming flow are tested. These calculations are performed with allowance for interaction of shock waves emanating from the heated gas region and from the body in the far field. The computational results show that the local heat supply to a supersonic gas flow ahead of a body can reduce the sonic boom level by more than 20 %. The reduction of the sonic boom level is ensured by changing the free-stream parameters ahead of the body and by preventing the coalescence of shock waves from the heat supply zone and from the body in the far field. 相似文献
4.
The problem of reduction of the sonic boom level by heating the flow in front of the body is solved numerically. A combined method of “phantom bodies” is used for calculations. The sonic boom generated by an axisymmetric thin body for the flight Mach number of 2 with different levels of energy supply to the incoming flow is calculated. The calculation results show that the sonic boom can be reduced by means of local heat supply to a supersonic gas flow. Reduction of the sonic boom level is provided by specific gas-dynamic features of the flow behind the heat supply zone. 相似文献
5.
An experimental investigation is conducted to bring out the effects of coolant injector configuration on film cooling effectiveness,
film cooled length and film uniformity associated with gaseous and liquid coolants. A series of measurements are performed
using hot air as the core gas and gaseous nitrogen and water as the film coolants in a cylindrical test section simulating
a thrust chamber. Straight and compound angle injection at two different configurations of 30°–10° and 45°–10° are investigated
for the gaseous coolant. Tangential injection at 30° and compound angle injection at 30°–10° are examined for the liquid coolant.
The analysis is based on measurements of the film-cooling effectiveness and film uniformity downstream of the injection location
at different blowing ratios. Measured results showed that compound angle configuration leads to lower far-field effectiveness
and shorter film length compared to tangential injection in the case of liquid film cooling. For similar injector configurations,
effectiveness along the stream wise direction showed flat characteristics initially for the liquid coolant, while it was continuously
dropping for the gaseous coolant. For liquid coolant, deviations in temperature around the circumference are very low near
the injection point, but increases to higher values for regions away from the coolant injection locations. The study brings
out the existance of an optimum gaseous film coolant injector configuration for which the effectiveness is maximum. 相似文献
6.
The laws of heat transfer associated with the interaction of underexpanded supersonic gas jets and obstacles or blunt bodies
have been investigated, for example, in [1–3]. Similar problems of nonuniform flow occur when bodies move in the wake behind
other bodies; however, in this case the laws of heat transfer have so far received little attention [4–8]. It has been established
that for a certain Reynolds number and flow nonuniformity parameters a zone of reverse-circulatory flow develops near the
front of the blunt body. However, the conditions of transition to separated flow have not been determined. This paper presents
a self-similar solution of the equations of the viscous shock layer near the stagnation line in supersonic flow past an axisymmetric
blunt body located behind another body. On the basis of this solution a separationless flow criterion is proposed. The effect
of the nonuniformity and the Reynolds number on the shock standoff distance, the convective heat flux and the friction drag
of the blunt body is investigated.
Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 120–125, November–December, 1986.
In conclusion the authors wish to thank I. G. Eremeitsev for useful suggestions and G. A. Tirskii for discussing their work. 相似文献
7.
An approximate analytical model for calculation of the parameters of a steady gas flow inside a plane constricting channel
formed by two symmetrically positioned wedges is suggested. A Mach configuration of shock waves (triple point) is formed in
the channel when the wedge angles are larger than some critical value. The flow calculation in a constricting channel reduces
to the solution of the iterative problem for a system of nonlinear algebraic equations. The configurations of shock waves,
the slipstream, and the sonic line are described by the proposed model of a gas flow. A comparison of the results obtained
using this model allows a fairly accurate calculation of the Mach stem and the length of the subsonic-flow region.
Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated
from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 52–58, May–June, 1998. 相似文献
8.
An array of microphones is used to study the space–time characteristics of the wall-pressure field beneath a forced separation
bubble downstream of an axi-symmetric backward-facing step. To excite the flow, an externally driven Helmholtz resonator is
employed. A unique aspect of the present study is the utilization of an amplitude-modulated forcing scheme in order to avoid
contamination of the measured hydrodynamic pressure fluctuations by acoustic radiation from the forcing device. The results lead to the hypothesis that the optimal forcing frequency is achieved when
the forced disturbance originates near the center of the unforced separation bubble in the limit of very low levels of forcing. Moreover, a frequency–wavenumber spectrum analysis highlights the possibility for achieving separation control while minimizing
potential acoustic radiation due to coupling between the forced disturbance and resonant modes of the underlying surface. 相似文献
9.
H.G. Hornung 《Shock Waves》1998,8(1):11-21
The inviscid equations of motion for the flow at the downstream side of a curved shock are solved for the shock–normal derivatives.
Combining them with the shock–parallel derivatives yields gradients and substantial derivatives. In general these consist
of two terms, one proportional to the rate of removal of specific enthalpy by the reaction, and one proportional to the shock
curvature. Results about the streamline curvature show that, for sufficiently fast exothermic reaction, no Crocco point exists.
This leads to a stability argument for sinusoidally perturbed normal shocks that relates to the formation of the structure
of a detonation wave. Application to the deflection–pressure map of a streamline emerging from a triple shock point leads
to the conclusion that, for non–reacting flow, the curvature of the Mach stem and reflected shock must be zero at the triple
point, if the incident shock is straight. The direction and magnitude of the gradient at the shock of any flow quantity may
be written down using the results. The sonic line slope in reacting flow serves as an example. Extension of the results –
derived in the first place for plane flow – to three dimensions is straightforward.
Received 12 February 1997 / Accepted 10 June 1997 相似文献
10.
A. V. Pinaev V. T. Kuzavov V. K. Kedrinskii 《Journal of Applied Mechanics and Technical Physics》2000,41(5):836-844
Profiles and values of pressure in shock waves are determined for the case of spherical, linear, and spatial charges, such
as a coil of a bulk spiral and plane annular coils and Archimedes’ spiral of various lenths, exploded in air. In the case
of explosion of rings and spirals, a complex wave structure in the form of a sequence of several shock waves is registered
near the charges along the spiral axes; a weaker attenuation of shock waves with distance and pressure amplitudes two to three
times higher than in the case of a spherical charge of the same mass are observed. It was found that an increase in the length
of a plane spiral does not lead to an increase in the maximum pressure in the shock wave at distances of the order of several
pitches of the spiral from its plane. With distance from spatial charges of different shape but identical mass, the pressure
values in the shock-wave fronts coincide and tend asymptotically to the parameters of a spherical explosion with a significant
increase in the duration of a wave packet generated by the spatial charge. Dependences for evaluation of shock-wave pressure
amplitudes in the near zone of the explosion are presented.
Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 5, pp. 81–90, September–October, 2000. 相似文献
11.
M. D. Anokhin Yu. A. Vinogradov A. I. Zubkov B. E. Lyagushin Yu. A. Panov 《Fluid Dynamics》1998,33(2):186-189
The three-dimensional shape of the shock wave formed ahead of a sonic jet flowing out into a supersonic flow through the surface
of a sharp cone is determined. The shape of the wave in the longitudinal and transverse cross-sections of the model is constructed
using schlieren photographs taken for various angles of rotation and freestream Mach numbers M=1.75–3.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 41–44, March–April, 1998.
This research was carried out with financial support from the Russian Foundation for Basic Research (project No. 95-01-00709a). 相似文献
12.
The paper presents results of a numerical simulation of a supersonic two-dimensional (2D) viscous flow containing CO2 molecules near a spacecraft entering the Mars atmosphere. The gas–dynamic equations in the shock layer are coupled to the
equations of non-equilibrium vibrational and chemical kinetics in the five-component mixture CO2/CO/O2/C/O. Transport and relaxation processes in the flow are studied on the basis of the rigorous kinetic theory methods; the
developed transport algorithms are incorporated in the numerical scheme. The influence of the vibrational excitation of CO2 and chemical reactions on the gas flow parameters and heat transfer is analyzed. The obtained results are compared with those
found using two simplified models based on the two-temperature and one-temperature vibrational distributions in CO2. The accuracy of the simplified models and the limits of their validity within the shock layer are evaluated. The effect
of bulk viscosity in a flow near a re-entry body is discussed. The role of different diffusion processes, chemical reactions,
and surface catalytic properties in a flow of the considered mixture in the shock layer is estimated. 相似文献
13.
The problem of the axisymmetric potential flow past a body of revolution with a channel along the axis in the presence of
a recirculation flow zone near the body, first proposed by G. Yu. Stepanov, is solved.
Kazan’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 14–21, January–February,
2000.
The study was carried out with the support of the Russian Foundation for Basic Research (project No. 96-01-00123). 相似文献
14.
A. A. Markov 《Fluid Dynamics》1987,22(5):753-760
Unsteady supersonic flow regimes in the neighborhood of a stagnation point are investigated on the basis of a system of viscous shock layer equations [10] containing all the terms of the Euler equations and the boundary layer equations. An analytic solution of the unsteady equations valid near the surface of the body is found in the case of strong injection. The unsteady equations of the viscous shock layer are solved numerically on the basis of a divergent implicit scheme of the second order of approximation across the shock layer, using Newtonian linearization and vector sweep methods with allowance for the boundary relations on the surface of the body and at the isolated bow shock. Certain calculation results illustrating the effect of injection, surface cooling, the swirl of the external flow and the angular velocity of the body on the structure of the steady and unsteady viscous shock layer are presented.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 114–122, September–October, 1987. 相似文献
15.
V. M. Fomin V. I. Zapryagaev A. V. Lokotko V. F. Volkov 《Journal of Applied Mechanics and Technical Physics》2012,53(3):333-339
Results of experimental and numerical investigations of the effect of gas injection through a permeable porous surface on the drag coefficient of a cone-cylinder body of revolution in a supersonic flow with the Mach number range M h = 3–6 are presented. It is demonstrated that gas injection through a porous nose cone with gas flow rates being 6–8% of the free-stream flow rate in the mid-section leads to a decrease in the drag coefficient approximately by 5–7%. The contributions of the decrease in the drag force acting on the model forebody and of the increase in the base pressure to the total drag reduction are approximately identical. Gas injection through a porous base surface with the flow rate approximately equal to 1% leads to a threefold increase in the base pressure and to a decrease in the drag coefficient. Gas injection through a porous base surface with the flow rate approximately equal to 5% gives rise to a supersonic flow zone in the base region. 相似文献
16.
A. V. Potapkin D. Yu. Moskvichev 《Journal of Applied Mechanics and Technical Physics》2011,52(2):169-177
An algorithm is proposed for calculating the parameters of weak shock waves at large distances from their origination. In
chosen meridional planes, the parameters of the near field of the three-dimensional flow are used to determine the streamwise
coordinates of “phantom bodies” by linear relations. When the initial body is replaced by a system of “phantom bodies” for
which discrete values of the Whitham function are found, the far-field parameters are calculated by the Whitham theory, independently
in each meridional plane. Results calculated for a body with axial symmetry and for bodies with spatial symmetry are presented. 相似文献
17.
The effect of the scheme of fluid injection into a stratum on the length and the hydraulic drag of the initial portion of
the flow through the porous medium and on the flow rate intercepted by a drainage slit separating the stratum from and end
wall is investigated. The asymptotics of large and small values of the hydraulic conductivity coefficient of this slit are
constructed.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 60–67, January–February,
1999.
The work was carried out at the Moscow State Chemical Industry Academy. 相似文献
18.
The hydrodynamics of processes occurring in explosion of condensed explosives in air is considered. The physical model, computation
technique, and results of simulation of a two-dimensional hydrodynamic flow arising in explosion of cylindrical charges are
discussed. In this case, the explosions are considered at some distance above the ground. To close the gas-dynamics equations,
the Jones–Wilkins–Lee equation of state is used. The results of calculation allow one to obtain a detailed space–time pattern
of the arising flow and to study the origination, propagation, and subsequent attenuation of shock waves. Cylindrical charges
of the same mass but with different diameter-to-length ratios are considered. It is shown that the charge shape can render
essential influence on dynamics of flow and the parameters of shock waves (in the near and medium fields of explosion). 相似文献
19.
The flow with a free-stream Mach number M
∞ = 6 around a cylindrical body with a sharp spike is studied. The existence of a supersonic reverse flow for one of the phases
of the pulsating flow regime is experimentally validated. A range of spike lengths is determined, which ensures a region of
a supersonic reverse flow near the side surface of the spike. The time of existence of the supersonic reverse flow region
is shown to be 0.15 of the period of pulsations if the spike length equals the model diameter.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 30–39, July–August, 2007. 相似文献
20.
低声爆设计方法已成为新一代军民用超声速飞机研制过程中必须解决的关键难题之一。针对传统SGD低声爆外形反设计方法无法对声爆近场非线性效应进行描述和分析的缺点,提出了利用CFD方法求解得到的声爆近场压力分布代替F函数进行低声爆反设计的方法。声爆近场预测采用点-点对接的结构/非结构混合网格,充分利用非结构网格对复杂外形适应性强和结构化网格计算效率高的优点。结果分析表明,基于改进后的低声爆反设计方法得到的方案在声爆超压以及感觉噪声级等方面都比基于原始SGD方法得到的方案有较大改善。 相似文献