Specific impulse losses due to friction and dispersion in a gas-film cooled liquid rocket engine nozzle

Conclusions The proposed method and program for calculating the compressible turbulent boundary layer in rocket engine nozzles with gas film cooling make it possible to determine the specific impulse losses due to friction, the heat fluxes and other characteristics of the flow. The calculations are based on the numerical solution of the equations of gas dynamics in the boundary layer approximation using a three-parameter differential turbulence model.The calculations for nozzles without film cooling showed that the contours occupying a narrow interval between the families of contours with uniform and variational characteristics have the minimum impulse losses due to friction and dispersion. In contrast to the known results, the loss minimum is displaced relative to nozzles with a variational characteristic (Rao nozzles) towards truncated nozzles with a uniform characteristic.The dependence of the maximum heat transfer to the wall in the critical throat section of the nozzle on the rate of flow of fuel into the film has been determined for nozzles with film cooling. It is shown that as the film flow rate increases, the friction losses decrease, and the minimum of the impulse losses due to friction and dispersion is shifted towards the contours with a variational characteristic, which have the minimum dispersion losses. The total impulse losses, which take into account the change in the fuel component ratio in the flow core due to the diversion of part of the fuel into the film, increase with increase in the film flow rate.The results of our numerical investigation of the effect of the contour shape and film flow rate indicate that the contour with a variational characteristic, which has near-minimum specific impulse losses due to friction and dispersion, should be used as the optimum contour for LRE nozzles.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.4, pp. 82–93, May–June, 1993.deceased.The authors wish to thank their colleagues at the Énergomash NPO L. P. Vereshchak and L. K. Danilyuk for assisting with the calculations, the participants in G. A. Lyubimov's seminar for discussing the results obtained, and D. A. Mel'nikov, U. G. Pirumov, and A. A. Sergienko for valuable advice.     

1,1,2,2-tetraaminoethane derivatives: III. Condensation of 2-(Dinitromethylene)imidazolidine-4,5-diol with nitrogen-containing nucleophiles

Condensation of 1,1-diamino-2,2-dinitroethylene with glyoxal and formaldehyde in water solutions at pH 7–8 gave rise to 2-(dinitromethylene)imidazolidine-4,5-diol and 1,1-diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene respectively. Condensation products of 2-(dinitromethylene)imidazolidine-4,5-diol with acetonitrile, benzonitrile, urethane, 3,4-diaminofurazan were isolated. The reaction of 4,5-diacetamido-2-(dinitromethylene) imidazolidine sulfate with water in acetonitrile led to the formation of 2-(dinitromethylene)-5-methyl-1,2,3,3a,4,6a-hexahydroimidazo[4,5-d]imidazole. The dehydration of 2-(dinitromethylene)imidazolidine-4,5-diol in a system H₂SO₄-AcOH provided 2-(dinitromethylene)-2,3-dihydro-1H-imidazol-4-ol. 1,1-Diamino-N,N′-bis(hydroxymethyl)-2,2-dinitroethylene in sulfuric acid was converted into 4-(dinitromethylene)-1,3,5-oxadiazinane.     

The Tail Wags the Dog: The Far Periphery of the Coordination Environment Manipulates the Photophysical Properties of Heteroleptic Cu(I) Complexes

In this work we show, using the example of a series of [Cu(Xantphos)(N^N)]⁺ complexes (N^N being substituted 5-phenyl-bipyridine) with different peripheral N^N ligands, that substituents distant from the main action zone can have a significant effect on the physicochemical properties of the system. By using the C≡C bond on the periphery of the coordination environment, three hybrid molecular systems with −Si(CH₃)₃, −Au(PR₃), and −C₂HN₃(CH₂)C₁₀H₇ fragments were produced. The Cu(I) complexes thus obtained demonstrate complicated emission behaviour, which was investigated by spectroscopic, electrochemical, and computational methods in order to understand the mechanism of energy transfer. It was found that the −Si(CH₃)₃ fragment connected to the peripheral C≡C bond changes luminescence to long-lived intra-ligand phosphorescence, in contrast to MLCT phosphorescence or TADF. The obtained results can be used for the design of new materials based on Cu(I) complexes with controlled optoelectronic properties on the molecular level, as well as for the production of hybrid systems.     

Detection of Surface States in Bi2 – xSbxTe3 – ySey Topological Insulators by Magnetotransport Measurements

Physics of the Solid State - In this paper, we studied the effect of the magnetic field and temperature on conductivity of Bi2 ‒ xSbxTe3 – ySey...     

Influence of Surfactants on Hydrocarbon Mobility in Narrow Pores in the Presence of Water

Colloid Journal - Molecular dynamics simulation has been employed to study the influence of standard surfactants and other additives used in oil production on the mobility of a liquid that occurs...     

The kinetics of low-temperature liquid phase epitaxy in the Zn-Cd-Te system

The kinetic corrections for the supersaturation of the initial liquid phase providing the preparation of Zn _x Cd_{1 − x} Te solid solution layers at low deposition temperatures (500–600°C) were found. The results of kinetic modeling were in satisfactory agreement with the experimental data. It was shown that the inclusion of corrections for supersaturation of the initial liquid phase to the data on phase equilibria in the Zn-Cd-Te system was necessary for finding the temperature-time conditions of the crystallization of layers with the required composition.     

Fused Imidazoles: II. Synthesis of Nitro Derivatives of 6,7-Dihydro-5H-pyrrolo[1,2-a]imidazoles

Russian Journal of Organic Chemistry - Nitration of 6-substituted 2-chloro-6,7-dihydro-5H-pyrrolo[1,2-a]imidazoles was used to synthesize the corresponding 3-nitro derivatives. 6-Substituted...