Numerical investigation of the accuracy of particle image velocimetry technique in gas-phase detonations

We numerically investigate the accuracy of the Particle Image Velocimetry (PIV) technique for the flow characterization in high-speed, compressible regimes, in particular in gas-phase detonations. We carry out synthetic PIV reconstruction of the flow field in a two-dimensional, planar detonation propagating under atmospheric conditions and modelled using single-step Arrhenius kinetics. The flow is uniformly seeded with monodispersed Al₂O₃ particles with sizes 50 and 200 nm, along with initially co-located massless Lagrangian tracer particles. The effect of massive particles on the detonation speed and thermodynamic state of the flow is investigated and is found to be negligible. We further assess the ability of massive particles to sample the flow field and while it is found that 50 nm particles sample the flow field better than the 200 nm ones, they also exhibit significant clustering. By comparing the trajectories of massive particles with those of massless tracers, it is shown that almost all massive particles rapidly diverge from the actual flow pathlines. Finally, we quantify the accuracy of the PIV reconstruction of the velocity field in comparison with the actual velocity field in the numerical simulations. It is shown that while PIV is generally capable of capturing the bulk flow features in the streamwise direction, its accuracy is not sufficient to characterize the transverse velocity component or velocity fluctuations.     

Compressible turbulent flame speeds of highly turbulent standing flames

In this paper we present the first measurement of turbulent burning velocities of a highly turbulent compressible standing flame induced by shock-driven turbulence in a Turbulent Shock Tube. High-speed schlieren, chemiluminescence, PIV, and dynamic pressure measurements are made to quantify flame–turbulence interaction for high levels of turbulence at elevated temperatures and pressure. Distributions of turbulent velocities, vorticity and turbulent strain are provided for regions ahead and behind the standing flame. The turbulent flame speed is directly measured for the high-Mach standing turbulent flame. From measurements of the flame turbulent speed and turbulent Mach number, transition into a non-linear compressibility regime at turbulent Mach numbers above 0.4 is confirmed, and a possible mechanism for flame generated turbulence and deflagration-to-detonation transition is established.     

Computation of fluid flows in non-inertial contracting, expanding, and rotating reference frames

We present the method for computation of fluid flows that are characterized by the large degree of expansion/contraction and in which the fluid velocity is dominated by the bulk component associated with the expansion/contraction and/or rotation of the flow. We consider the formulation of Euler equations of fluid dynamics in a homologously expanding/contracting and/or rotating reference frame. The frame motion is adjusted to minimize local fluid velocities. Such approach allows to accommodate very efficiently large degrees of change in the flow extent. Moreover, by excluding the contribution of the bulk flow to the total energy the method eliminates the high Mach number problem in the flows of interest. An important practical advantage of the method is that it can be easily implemented with virtually any Eulerian hydrodynamic scheme and adaptive mesh refinement (AMR) strategy.We also consider in detail equation invariance and existence of conservative formulation of equations for special classes of expanding/contracting reference frames. Special emphasis is placed on extensive numerical testing of the method for a variety of reference frame motions, which are representative of the realistic applications of the method. We study accuracy, conservativity, and convergence properties of the method both in problems which are not its optimal applications as well as in systems in which the use of this method is maximally beneficial. Such detailed investigation of the numerical solution behavior is used to define the requirements that need to be considered in devising problem-specific fluid motion feedback mechanisms.     

5,6-Dihydro-4H-imidazo[4,5,1-i,j]quinoline derivatives

9-Substituted 5,6-dihydro-4H-imidazo[4,5,1-i,j]quinolines were synthesized and aminated by the action of sodium amide and hydroxylated by fusing with potassium hydroxide. The mononitro and dinitro compounds of some 5,6-dihydro-4H-imidazo[4,5,1-i,j]quinoline deivatives and the corresponding amino and diamino compounds were obtained. The latter react with nitric or formic acids to form a new heterocyclic ring.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 242–246, February, 1972.     

Fluorine-containing azoles. 4. 2-Perfluoropolyoxaalkyl-substituted perimidines

The reaction of 1,8-naphthylenediamine with perfluoropolyoxaalkanoyl fluorides and -fluorosulfonylperfluropolyoxaalkanoyl fluorides yielded 2-perfluoropolyoxaalkyl-substituted perimidines. Their basicity and sulfonation by sulfuric acid were studied.For communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 973–975, July, 1986.     

5,6-Dihydro-4H-imidazo[4,5,1-i,j]quinoline derivatives

The oxidation of 2-hydroxymethyl and 2-methyl derivatives of 5,6-dihydro-4H-imidazo[4,5,1-i,j] quinoline with active manganese dioxide and selenium dioxide gave 2-formyl derivatives of this heterocycle. Some transformations of these compounds are realized.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 967–969, July, 1971.     

一种EGA—MS系统的标定方法

ＣａＣ２Ｏ４真空热分解中，第一阶段生成的ＣＯ中４７％歧化成ＣＯ２和Ｃ；第二阶段生成的ＣＯ与第一阶段生成的Ｃ发生气化反应，发生反应的比例随样品量增加而增大。用ＣａＣＯ３标定ＣＯ后再用ＣａＣ２Ｏ４标定ＣＯ可以排除这些干扰。本文提出了一个对任意气体标定的方法。