Calculation of spatial flow past an inclined flat plate with a detached shock wave

The results of a numerical analysis of a supersonic underexpanded jet impinging on an inclined flat plate are presented. The effects of the angle between the plate and the jet symmetry axis, the distance from the nozzle exit section, the exit Mach number, and the off-design conditions on the distribution of the gasdynamic parameters in the jet flowfield and on the plate surface are demonstrated. Specific features of the compressed layer and obstacle surface flows are revealed. The three-dimensional flow is simulated using the large particle method on the basis of the nonstationary Euler equations written in the cylindrical coordinate system. The calculated results are compared with experimental data. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 31–35, January–February, 1997.     

Spanwise propagation of turbulence in a boundary layer

The process of spanwise propagation of turbulence in a laminar boundary layer on a plate is numerically investigated. Three well-known turbulence models are considered. It is shown that the calculated values of the "turbulent wedge" angle are several times less than that observed experimentally. The reason for the deviation of the calculated and experimental data is analyzed. Moscow, Seattle. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 77–84, May–June, 1998. The work was financially supported by the Russian Foundation for Basic Research (project No. 95-01-00251a) and the Moscow Boeing Science-Technology Center.     

Turbulence suppression in subsonic jets by high-frequency acoustic excitation

The influence of high-frequency acoustic excitation of a submerged round turbulent jet flowing out of a nozzle with both laminar and turbulent boundary layers at the nozzle outlet on the suppression of turbulent velocity fluctuations in the initial and transition regions of the jet is experimentally investigated. It is established that in the case of the turbulent boundary layer a higher excitation level is needed to realize the suppression effect than in the case of the laminar boundary layer. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 28–34, January–February, 1999. The study was carried out with the support of the Russian Foundation for Basic Research (project No. 96-02-19577).     

Thermostressed State of an Anisotropic Plate with Holes and Cracks

The thermoelastic problem for an infinite multiply connected anisotropic plate with holes and cracks in a linear heat flow is solved. The stress distribution and the stress intensity factors on heat-insulated boundaries are analyzed numerically __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 9, pp. 127–136, September 2005.     

Some features of the flow around rapidly rotating bodies made of cellular-porous materials

Two types of gas flows arising near a rapidly rotating cellular-porous disk are studied numerically and experimentally. Steady-state limits for the flow around a disk rotating in free space and the type and scenario of the loss of stability are determined. Transitional flows are characterized by formation of a vortex sheet at the boundary of the exhausting jet. Numerical simulations of the flow around a cellular-porous disk rotating near a flat screen show that it is possible to form a closed swirl flow responsible for redistribution of swirl in the gap between the disk and the flat screen. The computed results offer an explanation for the experimentally observed excess of tangential velocity of the flow in the gap over the velocity of disk rotation. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 1, pp. 86–96, January–February, 2007.     

Regularities of the stretching and plastic failure of metal shaped-charge jets

The results of physicomathematical modeling obtained within the framework of continuum mechanics by numerical solution of the two-dimensional axisymmetric nonstationary problem of the dynamic deformation of a compressed elastoplastic bar of variable section are presented. Dependences of the quantitative characteristics of stretching and breakup of a shaped-charge jet (the coefficients of ultimate and inertial elongation and the number of individual elements formed in breakup) on the jet parameters and the jet material properties are revealed by calculations. The calculated dependences are compared with experimental data for plastically failing jets of copper and niobium, and the character of the dependences is explained from the physical viewpoint. Bauman Moscow State Technical University, Moscow 107005. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 25–35, July–August, 1999.     

Transition to turbulence in supersonic jets of nitrogen and argon

Laminar-turbulent transition in the mixing layer of supersonic nitrogen and argon jets has been studied experimentally using a local pulse diagnostic technique based on the Rayleigh light scattering effect. It was found that, in the argon jet, the transition to turbulence occurs at smaller Reynolds numbers than in the nitrogen jet. Among the possible reasons for this, the effects of the specific heat ratio and the second viscosity on the transition to turbulence are discussed. Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 196–200, May–June, 1998. The work received financial support from the Russian Foundation for Basic Research (project No. 96-01-01565).     

Sound generation by interacting vortices in a subsonic turbulent jet

The results of an experimental investigation of sound generation by the interacting toroidal and oblique vortices formed in a subsonic turbulent jet under the action of saw-tooth finite-amplitude sound waves with simultaneous longitudinal internal and transverse external excitation are presented (the sound pressure level on the jet edge is 165–175 dB). The direct schlieren method with an exposure time −3·10⁻⁷ s was employed. This made it possible to visualize not only the jet and the vortices formed in it but also the sound waves. It was confirmed experimentally that the vortex interaction may be accompanied by sound generation of fairly high intensity. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 54–60, January–February, 2000.     

Experimental and numerical modeling of the turbulent wake of a self-propelled body

The development of the turbulent axisymmetric wake of a self-propelled body is modeled experimentally and numerically. Experimentally, the self-propulsion regime was implemented in the wake of a body of revolution whose hydrodynamic resistance was completely compensated by the pulse of a swirling jet rejected from its trailing part, and the jet-induced swirling was counterbalanced by the rotation of a part of the body surface in the opposite direction. The second-order semiempirical turbulence model that includes the differential equation of motion. the transfer of the normal Reynolds stresses, and the dissipation rate was used to describe this wake mathematically, and the nonequilibrium algebraic relations were used to determine the tangential stresses. A satisfactory agreement between the calculation results and the experimental data is shown. Degeneration of the distant turbulent wake is investigated numerically. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 4, pp. 49–58, July–August, 2000.     

A turbulent plane offset jet with small offset ratio

 Mean velocities and turbulence characteristics of a turbulent plane offset jet with a small offset ratio of 2.125 have been studied using laser Doppler anemometry (LDA). Static pressure measurements highlight the importance of side plates in enhancing two-dimensionality of the jet. The spatial distributions of turbulence intensities and Reynolds shear stress show a high turbulence recirculating flow region close to the nozzle plate between the jet and the offset plate. The LDA results have been used to examine the capability of three different turbulence models (i.e. k–ɛ, RNG and Reynolds stress) in predicting the velocity field of this jet. While all three models are able to predict qualitatively the recirculation, converging and reattachment regions observed experimentally, the standard k–ɛ turbulence model predicts a reattachment length that best agrees with the experimentally determined value. Received: 11 September 1996/Accepted: 30 May 1997     

Modeling of heat transfer in a turbulent flow around a heat-conducting plate with local regions of heating

A solution of the coupled nonstationary boundary-value problem of turbulent flow around a flat heat-conducting plate of finite thickness having local regions with volume heat sources is given. For modeling the heat transfer in the boundary layer, thek-ε turbulence model is used. It is shown that the thermal conductivity of the plate material significantly affects the surface distributions of both temperature and local friction. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 79–86, November–December, 1998. The work received financial support from the International Scientific and Engineering Center (project No.199).     

Flow pattern in the vicinity of an annular system of transverse jets in a supersonic stream

The pattern of the flow in the vicinity of an annular system of jets exiting into a supersonic stream from orifices on a cylindrical surface with a turbulent boundary layer is experimentally investigated Four typical flow regimes are recorded The effect of the jet number and the nozzle-to-outer pressure ratio on the extent of the separation zone and its structure ahead of and behind the jet system is determined Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 21–27, January–February, 1999.     

Disturbance generation in a subsonic turbulent jet under the influence of high-intensity sound

The effect of high-intensity sound (L=140–160 dB) on a subsonic turbulent air jet under transverse external irradiation was studied experimentally. It is shown that the onset and development of disturbances in the early stage does not depend on the excitation frequency, while the intensity of the jet mixing is determined in large measure by the distance between the sound-generated vortices and by the degree of interaction between them. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 104–111, March–April, 1994.     

Heat transfer studies of the oblique impingement of round jets upon a curved surface

 The effect of jet inclination of the local heat transfer under an obliquely impinging round air jet striking on isothermal circular cylinder is experimentally investigated. The circumferential heat transfer distribution as well as axial Nusselt number is measured. The considered parameters are jet Reynolds number in range of 3800–40,000, and jet inclination angle, ranging from 90 to 20. The experiments are carried out for nozzle sizes, d=3, 5 and 7 mm, and separation distance from 7 to 30 of the nozzle diameter. The output results indicated that the point of maximum heat transfer along the x-axis is shifted upstream and the local heat transfer distribution changed as a function of jet inclination. The magnitude of the shift was found to be significantly higher than that observe for a flat plate. The increasing inclination caused increasing asymmetry around the point of maximum heat transfer, with the upstream side of heat transfer profile dropping off more rapidly than the downstream side. Correlations of both the magnitude and shift of maximum heat transfer point are presented. The surface average heat transfer rate is calculated and compared with the normal impingement. Received on 5 June 2000 / Published online: 29 November 2001     

Critical gas outflow from nozzles

The possibility of critical gas flow from Laval nozzles in overexpanded regimes behind a bridge shock is investigated theoretically with and without allowance for viscous mixing at the edge of the jet. The influence of the mixing effect and flow separation from the nozzle walls on the critical flow conditions is analyzed. It is shown experimentally that these regimes coincide closely with the displacement of the normal shock to the nozzle exit and cessation of the emission by the jet of a discrete tone. Mariupol. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 180–184, July–August, 1994.     

Identification of several impulsive loads on a plate

The paper presents a method to identify a system of several nonstationary independent transverse loads on a rectangular plate of medium thickness. The input data for solving the inverse problem are time-dependence of displacements or strains given at some points of the plate. Examples of numerical calculations to identify two or three loads are presented. The deformation of plates is modeled using a refined Timoshenko theory. Tikhonov’s regularizing algorithm is used to solve the Volterra equations for the unknown loads __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 90–97, July 2007.     

Multivelocity effects in high-pressure-gradient flows of dilute bubbly media

The multivelocity effects associated with the behavior of gas or vapor bubbles in a region with high pressure gradients typical of the flows around a cavity in which the pressure is higher than that in the surrounding space are considered. For a low volume bubble concentration, the problem of fluid flow perturbation by the bubbles is examined. For gas bubbles, it is shown that taking multivelocity effects into account considerably reduces the additional jet momentum. It is found that, with time, the temperature distribution in the wake behind a vapor bubble becomes nonmonotonic and the maximum temperature may even exceed the initial bubble temperature. It is demonstrated that the bubbles may accumulate and a flow regime with a sharply pronounced two-phase jet extending to the outer edge of the main liquid jet may develop. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 87–100, January–February, 1998. The work received financial support from the Russian Foundation for Fundamental Research (project No.96-01-01442).     

Numerical and asymptotic study of the two-dimensional problem of the hydroelastic behavior of a floating plate in waves

The problem of the behavior of a floating elastic plate in waves is solved numerically. The normal mode method is used. For a fluid of finite depth, the hydrodynamic coefficients are obtained in explicit form. Numerical results are compared with experimental data for the stress distribution in the plate and also with numerical results of other authors. The results are in good agreement for not very short waves. For incident waves whose wavelength is comparable with the length of the plate, a long-wave approximation of the solution is proposed. Within the framework of this approximation, the solution is given in analytical form. Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 90–96, March–April, 2000.     

Interaction of a shaped-charge jet with a target possessing an axial orifice

Interaction of a shaped-charge jet with a target possessing an axial orifice is studied experimentally. For an orifice diameter approximately equal to 0.2D, where D is the shaped-charge diameter, the shaped-charge penetration depth is found to be substantially reduced owing to deviation of the shaped-charge jet axis from the shaped charge axis because of imperfections of the manufacturing technology. A diameter of the target orifice providing unconstrained penetration of the shaped-charge jet is determined. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 13–16, November–December, 2008.     

Centrifugal Convection in Rapid Rotation of Bodies Made of Cellular-Porous Materials

Gas flows inside and around rapidly rotating bodies made of cellular-porous materials are studied numerically and experimentally. Within the framework of the previously proposed physicomathematical model, an appropriate numerical algorithm is developed and tested. Internal flows and a conjugate problem with the external flow are considered. The calculated moment and dynamic pressure are in good agreement with experimentally measured characteristics of a rotating porous disk on a solid substrate. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 1, pp. 46–57, January–February, 2006.