Burtsev

pp. 35-56

pp. 217-237

pp. 348-369

The paper investigates an influence of helium fraction on the Prandtl number value for various gas mixtures. It is shown that a low value of the Prandtl number allows us to raise efficiency of gasdynamic energy separation in Leontyev's tube. The paper conducts a numerical research of the influence of gas mixture composition on the Prandtl number value, and verifies the calculation procedure, using the known experimental data and calculation results of other authors. It is shown that there are binary mixtures of the "light" and "heavy" gases, possessing abnormally low value of the Prandtl number, and the used calculation procedure allows correct calculation of their thermo-physical properties.

This article presents an analysis of published data on numerical and physical (experimental) study of thermal-hydraulic characteristics of different methods of heat exchange vortical enhancement. It is shown that the most effective is the use of heat exchange surfaces coatedwith regular relief (holes) which have a simple production technology combined with high thermal-hydraulic characteristics. The authors present a modernized test bench that allows, in a single experiment, to determine resistance and heat exchange parameters for two plates which are parallel to each other (smooth plates and plates coated with regular relief). In this case, resistance is determined by "weighing" on tensometric scales, and parameters are determined by a time-dependent heat exchange method using thermal imaging equipment. The authors present data of an experimental study of two types of heating surfaces. It is shown that surfaces with oval holes have a large (20-35%) resistance than surfaces with hemispherical holes.

The authors consider the scheme which they previously introduced in cooperation with A.I. Leontyev. It is a closed gas turbine tri-generation unit operating on a sequential scheme. The unit can simultaneously produce electric power, heat and cold (on specified temperature levels) ensuring conditioning and/or thermostatic control. The results of the research of its thermodynamic cycle with the assumption of realistic efficiency of unit components and non-zero temperature differences in heat exchangers are presented in the article. The authors define the field of reasonable rates of pressure rise in the compressor. The pressure increase provides high efficiency and small-scale dimensions and mass of the energy unit. The authors propose recommendations on choosing the rate of pressure rise in the compressor for design simplification of a closed gas turbine tri-generation unit operating on sequential scheme.

This work describes the test configuration of gas dynamic energy disjunction device (Leontiev’s tube) working on the water and natural gas. This device works by means of local disbalance between heat generation and dissipation during the flow of compressible gas. Results of experimental investigation of the specified device are presented in the article; it was shown that the replacement of heat-transfer material in the external (infrasonic) channel (substitution of natural gas for water – heat-transfer material with greater heat transition coefficient) doesn’t change the efficiency of heat passage from the heat transfer agent flowing through the internal supersonic channel to the heat transfer agent flowing through the external infrasonic channel. Updated method of calculating this class of devices was proposed; the comparison of the results obtained from numerical experiments with a use of updated method with the results obtained from the same experiments with a use of basic method and experimental data was carried out. It was also shown that results of this research obtained using the updated method describe the growth of natural gas’ enthalpy better than ones obtained with a use of basic method.

The author carried out a retrospective analysis of influence of different factors on the value of the temperature recovery factor which affects, in certain way,  gas dynamic temperature lamination. It is shown that the value of the temperature recovery factor could be determined as a square root of the Prandtl number in case of a longitudinal laminar gas flow over simple bodies (plane, cone, and cylinder) within a wide range of parameters. In case of the turbulent longitudinal flow, the temperature recovery coefficient almost doesn’t depend on the Mach and Reynolds numbers and can be determined as a cubic root of the Prandtl number within the range from 0.5 to 2. It is also shown that the value of the temperature recovery factor decreased in case of an airflow over complex bodies in the presence of blowing; but this value could be determined only experimentally.

This works describes the test configuration of gas dynamic energy disjunction device (Leontiev’s tube) working on the natural gas. This device works by means of local disbalance between heat generation and dissipation during the flow of compressible gas. Results of experimental investigation of the specified device and measuring error estimate were presented in this article. Updated method of calculating this class of devices was proposed; it allows one to consider the intensification of heat transfer at the initial section of a supersonic channel along with the influence of the longitudinal pressure gradient and the longitudinal thermal conductivity of this device’s walls. The comparison of the results obtained from numerical experiments with a use of updated method with the results obtained from the same experiments with a use of basic method and experimental data was carried out. It was also shown that results of this research obtained using the updated method describe the growth of natural gas’ enthalpy better than ones obtained with a use of basic method.