Calculation of kinematic coagulation of an aerosol in a variable-speed gas stream

A method is suggested for calculating the kinematic coagulation of drops in a variable-speed gas stream when they are broken up by the gas stream. The results of the calculation are compared with test data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 4, pp. 698–704, October, 1978.     

示踪气体混合均匀性的试验研究

为探讨示踪气体与被测气体实现均匀混合的条件,以CO作为示踪气体,以空气作为被测气体,在直径为0.300 m的90°弯曲管道内对示踪气体与空气的混合均匀性进行了试验研究.结果表明,在本试验条件下,当混合气体流速大于3.2 m/s时,在弯管下游的12D(D为管道内径)和15D处,示踪气体的径向和轴向平均体积分数误差小于4%,示踪气体的实测平均体积分数与理论值趋于一致,可认为示踪气体与空气的混合达到了均匀.因此,工业气体的管道输送过程中采用示踪法校准气体流量计时,可在满足上述条件的位置处作为取样点.     

Effect of gas stream swirls on the instability of viscous annular liquid jets

Summary. A linear temporal instability analysis has been carried out for a viscous annular liquid jet moving in two swirling gas streams of unequal velocities with the gas stream swirling motion represented by free-vortex rotation. It is found that two modes of unstable surface waves exist, the para-sinuous and para-varicose mode. The results of the two limiting flow situations, which are a cylindrical liquid jet in a swirling gas stream and a swirling gas jet in a liquid stream, indicate that their instabilities are associated with the para-varicose mode on the outer interface and para-sinuous mode on the inner interface of the annular liquid jet, respectively. It is shown that the centripetal force induced by the inner gas stream rotation is destabilizing and enhances the jet instability, while the centripetal force produced by the outer gas stream rotation is stabilizing and reduces the instability of annular liquid jets. It is interesting to find that for a para-varicose mode an increase in the outer gas rotation not only reduces the upper cut-off wave number, but also increases the lower cut-off wave number, leading to the significant reduction in the unstable wave number range. The stabilizing effect of the outer gas rotation is much more significant for para-varicose mode, and the destabilizing effect of the inner gas rotation is much more influential for para-sinuous mode. In general, the para-sinuous mode has a much larger growth rate and is predominant in the annular liquid jet breakup process. Therefore, increasing the inner gas stream rotation can significantly enhance the breakup of annular liquid jets for practical spray applications.     

A decrease in the effective cross section of a cooling stream caused by hot air penetration into the blowout channel

The phenomenon of penetration of a hot air stream into a channel of finite depth by which a cooling stream is injected was revealed and studied by numerical methods. The penetrating stream decreases the effective cross section of the cooling stream, increases the velocity of this stream, and reduces the near-wall gas screen cooling efficacy.     

Preparation of accurate, low-concentration gas cylinder standards by cryogenic trapping of a permeation tube gas stream

National and international measurements are underpinned by accurate, low concentration standards. These standards are typically produced gravimetrically, or volumetrically, by a series of dilutions of the pure material by the balance gas. This blend technique is time-consuming and may involve the handling of pure, hazardous material. These problems have been overcome by developing a novel blend technique whereby the process gas stream, from an appropriate permeation tube, was cryogenically trapped in an aluminum cylinder. The permeation rate of the component is monitored by real time mass determinations using a magnetic suspension balance system. With the combination of the real-time calculated permeation rate, plus the use of a dilution system, a one step production of a very low concentration of the minor component in nitrogen gas can be achieved. This method was used to prepare low μmol/mol standards of propane, a known stable compound. Analysis of a conventional gravimetrically prepared 10 μmol/mol propane standard and a cryogenically prepared standard via a permeation gas stream resulted in agreement between the two of <0.1% at 10 μmol/mol, confirming the accuracy of the permeation method. After confirmation of the validity of the permeation/cryogenic trapping system, the propane permeation tube was replaced with a methyl mercaptan tube (a toxic, reactive compound) in balance nitrogen. After cryogenically trapping the methyl mercaptan output stream from the permeation system into a cylinder, the output stream and the cylinder gas mixture were analyzed. The results showed agreement of <0.6% for methyl mercaptan at 5, 10, 15, and 20 μmol/mol to the expected blend concentration, thereby demonstrating the validity of the method.     

A Humidity Generator for Temperatures up to 200?°C and Pressures up to 1.6?MPa

A new humidity generator that produces gas streams of known moisture content at temperatures from 85?°C to 200?°C, absolute pressures from 0.2?MPa to 1.6?MPa, and relative humidities from 10 % to 90 % has been developed. The generator produces a moist gas stream by injecting fixed-rate streams of dry gas and liquid water into a vaporizer, where the water evaporates into the gas. The gas stream passes into a re-entrant radio-frequency (RF) cavity, which serves as our reference hygrometer, and then a test chamber. The present standard uncertainty of the RF hygrometer is 0.6 %, limited by the uncertainty of literature values for the polarizability of water. Dry nitrogen gas purging the pressure transducer line also combines with the moist gas stream downstream of the test chamber and flows through one of a set of capillaries. Modulation of gas flow through the fixed flow impedance of the capillary gives a simple method for controlling pressure. Individual insulated, temperature-controlled aluminum ovens enclose each major component. A larger oven encloses these ovens and their connecting tubing. To minimize corrosion, critical components are constructed of high-nickel alloys. The small total volume (<1?L) and small flow rate (<0.5 L·min^?1) reduce operational hazards from steam scalding or from gas explosion.     

Breakaway of a liquid by a gas stream at an interface containing a grid

It is shown that in a system comprised of a gas stream, a liquid, and a grid, breakaway of a drop of liquid by the gas stream occurs under certain conditions. This paper determines the characteristic and dimensions at which drop breakaway will begin for a given gas velocity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 3, pp. 393–398, September, 1977.     

Procedure and test unit for studying the operating capacity of gas turbine engine blades under the combined action of mechanical and thermal loads,and atmosphere in a gas-dynamic test bed

A procedure and a gas-dynamic test bed are described for testing gas turbine engine blades with programmed mechanical and thermal loading. The test bed provides fatigue and heat resistance tests for GTE blades under conditions of the corrosive action of a high-temperature gas stream including variable thermodynamic parameters as well as other corrosive components, for example sea water salts injected into the stream in order to simulate GTE marine operating conditions.Deceased.Translated from Problemy Prochnosti, No. 6, pp. 71–77, June, 1993.     

Nonlinear spatial instability of an annular swirling viscous liquid sheet

Instability and breakup of a viscous annular liquid sheet that is exposed to co-flowing inner and outer gas streams have been investigated using a nonlinear spatial stability analysis. A perturbation expansion method is used with the initial amplitude of the disturbance as the perturbation parameter. The evolution of the two gas–liquid interfaces is tracked until the sheet breaks up and the breakup length is determined. The model is validated by comparison with available experimental data. The effects of liquid swirl strength, gas-to-liquid density ratio, radius of curvature ratio, and liquid viscosity on the sheet instability and breakup have been studied. The results show that at very low values of liquid swirl, it has a stabilizing effect on sheet breakup, but as the swirl strength increases, it strongly destabilizes the sheet. Also, with increasing swirl strength, the occurrence of the large surface deformations moves from the inner interface to the outer interface. The sheet breakup length increases slightly and then decreases rapidly with an increase in liquid swirl strength. Without liquid swirl, the axisymmetric mode is the dominant instability mode. However, with increasing liquid swirl strength, the higher helical modes become dominant and the breakup becomes increasingly asymmetric. When the undisturbed liquid sheet has a purely axial motion, the inner gas stream is more effective in sheet breakup than the outer gas stream. In the presence of liquid swirl, the outer gas stream is more disruptive than the inner gas stream. The breakup length becomes shorter as gas-to-liquid density ratio and the radius of curvature ratio increases. Increase in liquid viscosity tends to slow the disturbance growth and increases the sheet breakup length.     

Theory of the positive column of a nonsteady electric arc in a channel containing a gas stream

The problem of a nonsteady arc column in a channel containing a gas stream is solved for an arbitrary law of variation of the current with allowance for the variability of the gas density, flow velocity, and flow rate.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 4, pp. 648–652, April, 1982.     

Study of a liquid helium jet pump for circulating refrigeration systems

A basic diagram of the refrigeration system, in which liquid helium is circulated by means of a jet pump, is described. The equations have been derived to design jet devices which operate with liquid helium.In the experimental setup with a jet pump the flow rate of liquid was 5 to 10 times larger than that of compressed gas in a direct stream of the refrigerator. After pumping the pressure was equal to (0.15–0.40) × 10⁵Nm^?2. A circulating stream of liquid helium at supercritical pressure, due to the heat load corresponding to the refrigerator capacity, was heated to 0.15–0.25 K.The results of our studies permit one to determine circulation loop parameters and main geometric dimensions of the jet pump.     

A method of experimental determination of the profiles of temperature and composition of a high-temperature gas stream

A method of determining the parameters of a high-temperature gas stream based on the phenomenon of removal of mass from a plate placed in the stream is discussed. The possibility of applying the method is shown on a particular example.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 5, pp. 853–858, May, 1980.     

Experimental investigation of heat transfer in the region of a stagnation point

An investigation has been made of heat transfer to a body from a gas stream in the region of the stagnation point, as a function of enthalpy and stagnation pressure of the gas, and the velocity gradient at the stagnation point. The enthalpy of the gas (nitrogen) was varied from 6.5 · 10³ to 115 · 10³ kJ/kg, and the pressure from 10.3 to 14.7 N/cm². The upper enthalpy limit corresponded to an ionization level of x_N+=0.43. The investigation was carried out in a gas jet heated by means of an electric arc.     

Velocity measurements in a strongly swirling natural gas flame

The present study was focused on the turbulent velocity field of a central annular natural gas jet which penetrated a strongly swirling air flow. Due to the high swirl number S=0.95 and the high momentum ratio, the fuel jet was almost immediately integrated into the air stream. High rates of shear resulted in an intensive turbulent mixing process between natural gas and air. The central hub of the fuel exit annulus stabilized the reverse flow zone at a fixed location. The present nozzle configuration resulted in a very stable and symmetric flame.     

Laser-induced vapour-phase synthesis of titanium dioxide

Small-diameter titanium dioxide powders were synthesized from vapour-phase reactants that were heated with 10.591m infrared radiation from a CO₂ laser. Two reactants, titanium isopropoxide and titanium butoxide, were evaluated. Anatase powder was generated from titanium isopropoxide in both static gas and flowing gas configurations. The addition of oxygen to the titanium isopropoxide gas stream reduced the percentage of volatile components in the anatase powder. Detailed characterizations of the product powders are presented.     

Effect of a gas stream on the wave flow of thin layers of a viscous liquid

An analytical study was undertaken of the effect of a gas stream on the wave flow characteristics of thin layers of a viscous liquid moving over a vertical surface. The results of the investigations are compared with experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 6, pp. 989–994, December, 1969.     

Blunt bodies in a stream of nonequilibrium-ionized radiating gas

A supersonic stream of an inviscid tnonoatomic nonequllibrium-ionized radiating gas around blunt bodies is analyzed in this study. The results are illustrated by the example of an argon stream around spherically blunted bodies.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 4, pp. 681–687, October, 1973.     

Catalytic effects of carbon sorbents for mercury capture

Activated carbon sorbents have the potential to be an effective means of mercury control in combustion systems. Reactions of activated carbons in flow systems with mercury and gas stream components were investigated to determine the types of chemical interactions that occur on the sorbent surface. The effects of carbon type, particle size, temperature, and reactive gases were studied. Sorption kinetics and capacities for lignite- and bituminous-based carbons were compared with those for catalytic carbons at temperatures of 107 degrees C, 150 degrees C, and 163 degrees C. In the air and baseline gas studies, the catalytic carbons exhibited far better sorption than the lignite- and bituminous-derived carbons. With the catalytic carbons, the greater sorption kinetics and capacity in an air stream or baseline gas composition compared with nitrogen provides a clear demonstration that O(2) is required in the gas stream for higher reactivities and capacities. Thus, a catalytic chemisorption mechanism predominates for the sorption of mercury at these conditions. The reaction kinetics are inversely proportional to the temperature, indicating that a preliminary physisorption step with mercury associating with a surface site is rate-determining. In synthetic flue gas streams containing HCl (50 ppm), the sorption kinetics of the catalytic carbon are slightly inferior to those of lignite-based carbon. Thus, the reaction is dominated by a different interaction, where HCl reacts with mercury on the carbon surface and the oxidation sites on the catalytic carbon apparently have no advantage. Granular and fine-particle carbons gave similar results in flue gas streams.     

Influence of free convection on the rate of aerosol precipitation from a laminar gas stream

Results of experiments and computational estimates are presented which show that turbulization of a stream under the influence of free convection can substantially intensify aerosol deposition on channel walls from a laminar gas stream.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 1, pp. 44–49, July, 1977.     

Interaction of a granular stream with an obstacle

We investigate numerically the interaction of a stream of granular particles with a resting obstacle in two dimensions. For the case of high stream velocity we find that the force acting on the obstacle is proportional to the square of the stream velocity, the density and the obstacle size. This behaviour is equivalent to that of non-interacting hard spheres. For low stream velocity a gap between the obstacle and the incoming stream particles appears which is filled with granular gas of high temperature and low density. As soon as the gap appears the force does not depend on the square of velocity of the stream but the dependency obeys another law.