Thrust Performance of an Ideal Pulse Detonation Engine

Quasisteady and twodimensional unsteady formulations of the problem on the operation cycle of a pulse detonation engine are derived. A formula for the specific impulse is obtained, and the thrust performance of the engine is calculated. It is found that the thrust performance of this engine for flight Mach numbers M [0; 3.6] and compression ratios p ₂/p ₁ [1; 80] are always higher than those of the ramjet and onespool turbojet. As the compression ratio increases, the advantage of the pulse detonation engine becomes less noticeable.     

脉冲射流取样装置性能的实验研究

研究了一种无机械可动部件、可免维修的脉冲射流取样装置,以甘油-水体系为模拟对象,考察了体系粘度、压冲压力、T型节截面积和降液管长度对其取样性能的影响. 结果表明,随体系粘度从1.21 mPa×s增大到7.38 mPa×s,单次采样量从14.6 mL减小到6.1 mL;随T型节截面积增大单次采样量增大,并随体系粘度变大增大趋势更加显著;当降液管长度从2.65 m减至0.684 m时,单次采样量从19 mL锐减至3.8 mL,压冲压力对采样量几乎没有影响. 降液管中流体不连续流动导致的取样针底部出口处压力显著降低是采样驱动力的来源.     

工业炸药的爆轰性能研究

用有机玻璃法测定了岩石膨化、煤矿膨化、铵梯以及乳化炸药的爆速和爆压，同时用VLWR爆轰程序对岩11石膨化硝铵和铵梯炸药的爆轰参数及C—J产物的平衡组成进行了计算。结果表明，工业炸药具有低爆速和低爆压的非理想爆轰特征，而理论计算值和实验值比较接近，获得了较好的结果。     

Comparison of the Performance of a Pulsed Disc and Doughnut Column with a Pulsed Sieve Plate Liquid Extraction Column

Abstract

The hydrodynamic and mass‐transfer performance of a 75 mm diameter pulsed disc and doughnut column (PDD) and a pulsed sieve‐plate column (PSP) are presented and compared for a toluene–acetone–water system under similar operating conditions. It was found that the pulsed disc and doughnut column flooded earlier than the pulsed sieve‐plate column, indicating that the total throughput per unit cross‐sectional area through the pulsed disc and doughnut column was less. At similar operating conditions (i.e., flowrates, pulse frequency, and amplitude), the mass‐transfer performance of the pulsed disc and doughnut column was higher, and its holdup higher. The mass‐transfer performance of the PSP column, when compared at similar holdup to the PDD, was found to be higher, and so it is concluded that it is a more efficient column for this system.     

Dependence of the Shape of a Detonation Wave Front on the Detonation Wave Velocity upon Detonation of a Cylindrical Charge

The transition of a system of partial differential equations which describe the stationary flow behind the shock–wave front of a detonation complex upon detonation of a cylindrical charge to a system of ordinary differential equations is performed by means of the series expansion in terms of the radial variable. The necessary equations for determination of the derivatives of solutions with respect to the parameters and the initial conditions for them are formulated. Imposing the condition of continuous extendibility of the solutions leads to equations that allow one to determine the shape of a shock–wave front as a function of wave velocity.     

Predicting Detonation Performance of CHNOFCl and Aluminized Explosives

A new “hand‐calculated” method is introduced for prediction of detonation pressure of explosive and mixture of explosives with general formula CHNOFClAl. Suitable decomposition paths are used to estimate heat of detonation and detonation pressure. These decomposition paths are based on the distribution of oxygen atoms between carbon and hydrogen atoms as well as the degree of oxidation of aluminum. For CHNOFCl explosives, it is shown that the predicted detonation pressures with the new method are more reliable with respect to one of the best available empirical methods for loading densities greater than or equal 0.8 g cm⁻³. Since aluminized explosives have non‐ideal behavior, the new method does not require using full or partial oxidation of aluminum, which is usually required by a computer code. The predicted results of the new model also provide more reliable results than outputs of complex computer code with the BKWS equation of state.     

脉冲萃取柱空气脉冲旋转阀的特性

对脉冲萃取柱的空气脉冲旋转阀产生的空气脉冲发生过程进行了分析,给出了其充气和排气过程特征,得到脉冲腿内液面在空气脉冲作用下随时间变化的理论模型,并将理论计算结果与大型空气脉冲旋转阀产生的脉冲压力变化及在其作用下在直径0.3 m、高5.6 m无筛板脉冲柱中产生的液体运动的实验结果进行了对比. 结果表明,空气脉冲旋转阀充放气时间很短,充气时间约0.2 s,放气时间不超过0.05 s,加压空气通过旋转阀后产生接近梯形波的空气脉冲压力,脉冲柱内液面随时间变化曲线为类似正弦形,理论模型计算与实验结果符合很好,验证了模型的可靠性.     

Optimization of Potato Cube Drying in a Microwave-Assisted Pulsed Spouted Bed

The drying homogeneity of the microwave–pulsed spouted bed drying (MPSBD) method was studied via preparing tubers granules by MPSBD under different predefined conditions. The effects of three parameters (microwave power, moisture content transition point, and loading) on the homogeneity of prepared tubers granules were studied. Based on response surface analysis results, it was concluded that the optimum conditions for tuber granules prepared by MPSBD method is 1.10 W/g microwave power, 80% moisture content transition point, and 90 g material loading. It was proven that the experimental result from the predicted optimal condition agreed with the model-predicted results, which evidenced the accuracy of the response surface analysis. Furthermore, the brighter color and higher rehydration capacity of samples prepared by MPSBD indicates that MPSBD is a promising method that can be applied in the food dehydration industry.     

柴油性能对车用发动机的影响

柴油是柴油机的主要燃料,其使用性能和技术指标的控制对发动机正常工作有着深远的影响。文章简要介绍了发动机的工作原理,综述了柴油的物理化学性质对发动机的影响。     

Scale-Up Study on the Performance of Annular Pulsed Disc-and-Doughnut Columns

Based on the previous work of the hydraulic, axial mixing, and mass-transfer performance of an annular pulsed disc-and-doughnut column (APDDC), the effects of scaling-up on its performance were studied in APDDCs with different annular space widths. The effect of scaling-up on holdup was discussed, and a more universal correlation was established. The effect of scaling-up on the Sauter drop diameter could be expressed by the previous obtained correlation. The effects of scaling-up on both the flooding holdup and throughput were mainly reflected in the correlation of the Sauter drop diameter. The equations of operating regimes were also independent of the scaling-up effect as demonstrated by experimental data. The scaling-up effects on the axial-dispersion coefficient of the continuous phase, the mass-transfer coefficient, and the height of a transfer unit were also discussed.     

Detonation Performance of TATP/AN‐Based Explosives

The detonation velocity and performance were determined for four mixtures of triacetone triperoxide (3,3,6,6,9,9‐hexamethyl‐1,2,4,5,7,8‐hexoxonane, TATP), ammonium nitrate (AN) and water (W) by cylinder expansion tests. The composition of these mixtures varied in the following ranges: 21–31% TATP, 37–54% AN and 19–32% W. The obtained results were compared with those of powdery 2,4,6‐trinitrotoluene (TNT), AN‐fuel oil explosive (ANFO) and emulsion explosive. It was found that the tested TATP/AN/W mixtures represent typical non‐ideal explosives with relatively low critical diameter and with high sensitivity to initiation despite the high content of water due to the presence of the primary explosive (TATP). The detonation velocity is comparable to that of powdery TNT (at similar density). However, the acceleration ability is significantly lower than that of powdery TNT.     

Performance of an Industrial Pulsed Disc-and-Doughnut Extraction Column

Axial-dispersion and plug-flow models have been used to describe the solvent extraction performance of a 18 m high and 4 m diameter industrial pulsed disc-and-doughnut column. Uranium extraction phase-equilibrium data were fitted with the Langmuir model. Using the industrial column dimensions, operational parameters, physical properties, and the Langmuir parameters, the axial-dispersion model was shown to predict the organic-phase outlet concentration and the aqueous-phase outlet concentration, respectively, while the plug-flow model exhibited a poorer predictive ability.,     

Hydraulic Performance of an Annular Pulsed Disc-and-Doughnut Column

The annular pulsed disc-and-doughnut column (APDDC) is an important type of solvent-extraction equipment used in the PUREX process. Though it has been used in several commercial reprocessing plants in the world, there are few research results reported in the literature. In the present work, experiments were carried out in a stainless steel annular pulsed disc-and-doughnut column with aqueous phase and organic phase as the continuous fluid separately. The air-purge method was used to measure parameters including the two-phase densities, column weight, and two-phase interface location, which were fed back to a computer for column control. The holdup and Sauter drop diameter, the latter of which was calculated based on the gravitational settling model, are correlated as functions of the operating conditions (such as pulsation intensity, total flux, and flow ratio). Flooding holdup and throughput were determined experimentally and found in good agreement with those predicted by the model of the Sauter drop diameter. Based on the experimental data, operating regimes are divided referring to existing models. In addition, the effects of internal wettability on the hydraulic characteristics are also discussed.     

填充物对单孔双基推进剂爆轰性能的影响

为了提高装药的安全性,以非整体式圆环形双基推进剂为主装药,其间隙分别填充氧化剂混合胶液、空气、沙子、水、木屑、橡胶等,采用电离法和见证板法测定装药的爆轰性能。结果表明,用氧化剂混合胶液与水填充的主装药爆轰速度较大,空气填充的主装药爆轰不完全;得到用氧化剂混合胶液与空气填充时非整体式装药的爆速与装药药段长和空隙尺寸关系的表达式。     

Detonation Pressure of Donors as a Parameter for Assessing Detonation Transfer Probabilities

The commonly used penalty methods(such as Varicomp or varying the thickness of the out-of-line barriers), for determining the detonation transfer probability for an explosive interface, may become less practical or convenient the more insensitive explosive is the acceptor. The method proposed here suggests replacing the design donor by an explosive(substitute donor) of a lower detonation pressure. Both the acceptor and the mechanical hardware of the test system should be identical to those of the design system. It is assumed that the detonation pressures of both the design donor and the substitute donor are normally distributed. The same assumption holds also for the threshold detonation pressure required for initiating the acceptor. Following these assumptions we present a method to determine a minimum number of tests required to demonstrate a given reliability at a given confidence level. The relative standard deviation for each detonation pressure is assumed to be equal for all donors. We show then that the required number of tests to demonstrate a given reliability(at a given confidence level), practically depends on the ratio of the detonation pressures of the design donor and its test substitute. A similar method can be applied to demonstrate low probability of detonation transfer(high safety), by replacing the design donor by one of a higher detonation pressure.     

不同敏化材料对乳化炸药爆炸性能的研究

通过添加中空玻璃微球(CGM)和中空聚合物微球(CPM)两种不同敏化材料,制备两种不同乳化炸药,并对其爆速和密度、孔隙率的关系以及爆压进行了对比分析,研究表明,乳化炸药的爆速和密度呈现非线性关系,在同一密度下,CPM对乳化炸药的敏化效果比CGM好,且爆轰波在乳化炸药中传播时,被测炸药中CPM的爆压也略大于CGM的爆压。此外,综合对比爆速和爆压,表明乳化炸药孔隙率对爆轰性能具有重要影响,即一定条件下当孔隙率较大时可得到较大爆速和爆压,当孔隙率较小时,体系不具备雷管感度,不能起爆。此结果可为今后乳化炸药敏化发展提供指导作用。     

某LLM-105基传爆药生产工艺及性能研究

为研究某型1-氧-2,6-二氨基-3,5-二硝基吡嗪(LLM-105)基起爆药的性能,通过不同的重结晶工艺获得了不同形貌的炸药晶体,测试了其撞击感度;选用不同的粘结剂包覆炸药,通过钢块凹痕实验测试了其作功能力。结果表明:LLM-105在DMSO/水中重结晶并研磨后获得的炸药晶体对撞击钝感,LLM-105和Viton A质量比为97.5%/2.5%的药柱爆炸作功能力最强。此结果可为今后传爆药的发展提供指导作用。     

Experimental Study of Thrust Performance of a Hybrid Rocket Motor with Various Methods of Oxidizer Injection

A test bench and technique for experimental investigation of thrust performance of a hybrid rocket motor are described. A configuration of a rocket motor operating on a solid fuel (polymerized unsaturated hydrocarbon C₄H₆) and gaseous oxygen is proposed. Measured results for motor thrust are given. It is demonstrated that injection of a swirled oxygen flow into the motor duct increases the thrust performance of this kind of motors.     

Detonation of a highly diluted explosive

Detonation of mixtures of PETN with quartz sand with a 10–30% content of the explosive was investigated experimentally. Such systems are characterized by a low pressure and detonation velocity. The mass velocities of the solid filler and gas of the detonation products were measured by the electromagnetic method. With an explosive content of more than 15% the process is carried out by the leading shock wave and on the whole is single-velocity. The effects of a two-phase state are substantial with a low explosive content.Lavrent'ev Institute of Hydrodynamics. Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 3, pp. 124–130, May–June, 1994.