In the present work, results are reported of an experimental study of controlled periodic disturbances developing on a streaky structure in the shock layer of a model two-dimensional surface of compression. The experimental procedure was based on monitoring the electron beam induced fluorescence of nitrogen. Data were obtained concerning the streamwise phase velocity of density waves, the spatial distribution of shock-layer disturbances, and the rate of growth and transverse-wavenumber spectrum of density waves.
Unsteady expansion of the vapor into vacuum from a flat surface was studied by the direct simulation Monte Carlo method. The vapor was considered as monoatomic gas (the model of hard spheres). The flow structure and its parameters in the ranges of flow modes from free-molecular to continual were investigated. The main attention is paid to the structure of the Knudsen and subsonic layers.
The interaction between turbulent air flow and normally blown-in low-head axisymmetric jet was studied experimentally. Empirical dependencies were obtained for description of geometry of the dynamic and thermal boundary layers of a jet in cross flow. It was shown that for the initial path the jet is asymmetric in the vertical plane relative to the jet axis; the jet becomes almost cocurrent to the main flow even at small distance from the source. The jet in a cross flow has a higher ejection performance in comparison with submerged or cocurrent types of jets.
S.A. Isaev 1 , P.A. Baranov 1 , N.A. Kudryavtsev 1 , and T.A. Baranova 2 1 Academy of Civil Aviation, St. Petersburg, Russia 2 Lykov Institute of Heat and Mass Transfer, Minsk, Belarus
Pages: 83–101
A retrospective analysis of the works on numerical simulation of laminar flow and heat transfer through in-line tube banks, whose feature is the application of periodic boundary conditions, is given. An original procedure for correction of the bulk mean temperature is proposed. A multiblock factored algorithm for solving the Navier
The method for measurement of complex compliance of viscoelastic coatings based on direct determination of deformation amplitude and pulsation pressure was suggested. The value of dynamic deformation was ~ 0.02 %. The frequency range was 200 Hz – 2 kHz. Complex compliance of a viscoelastic coating measured experimentally was compared with calculation made on the basis of measured modulus of elasticity and loss factor of the coating material. Resonance frequency did not depend on the ratio between the contact area diameter and coating thickness. According to suggested explanation, coating deformation is defined by a stationary wave with oscillation node on solid basement and loop on the coating outside. Analysis showed that to obtain maximal coating deformation under the action of pulsation pressure, two conditions should be satisfied: influence frequency should be equal to resonance frequency of the coating (time factor), and the length of convective pressure wave should be equal to quadruplicated thickness of the coating (spatial factor).
Results of theoretical analysis for the equilibrium shape of liquid bridges produced by capillary ponderable liquid between two stacked cylinders are presented. The algorithm was developed to calculate the shape of bridge interface and numerical examples are given.
A two-temperature physical and mathematical model is developed for the process of heat and mass exchange between water and humid air at the stage of bubbles formation on the orifices of gas distribution grates of bubbling devices. The results of a numerical realization of the model have shown an insignificant variation of fluid temperature during the time from the bubble formation until its separation. It is also found that in most cases the fluid temperature in the bubbly layer (the temperature of gas-liquid layer) differs from the cooling liquid temperature. The two-temperature model enables the determination of cooling liquid temperature in the bubbly layer and then its importance at the computations conducted within the framework of the one-temperature model.
Experimental results on boiling crisis in the range of pressures close to the critical ones are presented for significant underheating of toluene at the tube inlet and compared with data obtained for water. Dependencies of the critical heat flux on the regime parameters are determined. The feature of boiling crisis in the range of pressures close to the critical ones is revealed. Equations for calculation of the critical heat flux at
P.S. Karabanov1 and V.A. Fukin2 1Novosibirsk Technological Institute of the Moscow State University of Design and Technology, Russia 2Moscow State University of Design and Technology, Russia
Pages: 137–144
The problem of the limiting duration of a liquid flow undergoing solidification in a plane-slot channel is solved. An analysis of solidification characteristics and an estimate of the limiting duration of the liquid flow are given. A comparison of experimental and analytical results showed a good agreement between them and has defined the scope of applicability of computed data.
a:2:{s:4:"TYPE";s:4:"TEXT";s:4:"TEXT";s:49:"S.V. Stankus, R.A. Khairulin, and P.V. Tyagel’sky";}
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Pages: 145–151
Thermal properties of eutectic Pb83Mg17 alloy were studied in solid and liquid states at the temperatures of up to 825 K by sample exposure by a narrow beam of gamma-radiation. Changes of specific volume at melting-crystallization were determined for the first time. Distribution of density over the sample height was measured. It is shown that eutectic alloy of Pb(Mg system is exposed to segregation. Non-equilibrium crystallization of a liquid alloy to metastable phases was found out. Density changes and characteristic temperatures of this process were determined. Volumetric alterations at transition of non-equilibrium inclusions to the equilibrium state were measured.
