bluuebunny/crossref_metadata_2025 huggingface dataset:
Sewage sludge conversion via hydrothermal liquefaction (HTL) – A preliminary study
Authors: Badrolnizam R S , Elham O S J , Hadzifah S N , Husain M H N , Hidayu A R , Mohammad N F , Mohamad Daud A R
Published: December 2019

Sewage sludge is regarded as a residue produced from municipal waste water treatment system. This waste is often used in low-value applications such as composting and incineration or disposed in landfills. Such practices posed many potential environmental hazards due to high levels of pollutants in the sludge. Sewage sludge is also a potential energy and currently received renewed attention for potential recovery of bio-oils and biochemicals through thermochemical conversion route. Hydrothermal liquefaction is a promising green method for conversion of sewage sludge. Hydrothermal liquefaction of sewage sludge were investigated at different temperatures (250°C, 300°C, 350°C and 400°C) and 1 hour reaction time. Experiments were carried out in a 10 ml stainless steel bomb reactor. The initial calorific value of sewage sludge was 12.36 MJ/kg. It was found that significant bio-oil yield of 52.23% and 48.25% were obtained at 350°C and 400°C respectively. Overall, the bio-oil yield increases with temperature up to critical temperature of water. It was clear that synergetic effect on the yield of liquid and solid were observed due to extended biomass fragmentations and depolymerization when reaction temperature was raised.The bio-oils produced from liquefaction of sewage sludge at 350°C contained an abundant number of ester based compounds, highlighting its potential as biofuel.
Effect of NCO/OH ratio on physical and mechanical properties of castor-based polyurethane grouting materials
Authors: Hussain N I A M , Bonnia N N , Hirzin R S F N , Ali E S , Zawawi E Z E
Published: December 2019

This research focused on fabrication of castor-based PU grout (CPUG) using castor oil with OH value of 161 mg/KOH/g and MDI with NCO content of 31%. The effect of different NCO/OH ratio on the foam reaction time, density, rheology, morphological and mechanical properties were investigated. The result shows that the rise time of CPUG decreased while tack free time increased with the increased of NCO/OH ratio. Morphological properties shows that CPUG consist of closed cell of foams and the diameter of a single cell foam decreased with the increased of NCO/OH ratio. The apparent density, rheology index, flexural strength, flexural modulus and compression strength of CPUG increased with the increasing NCO/OH ratio. CPUG’s apparent density was in the range of 230.23 kg/m3 while rheology index of CPUG was between 1.74 to 2.43 cm/g. Both values obtained were in the range of industrial PU grout’s density and rheology index (214 kg/m3 & 1.48 cm/g). CPUG4 give the best flexural and compression strength with a value of 11.01Mpa and 2Mpa respectively. Flexural and compression strength of CPUG were tantamount to the industrial PU grout’s properties which the average of flexural strength and compression strength were about 7.4MPa and 2MPa respectively.
Shape, size and dispersion of plant-driven silver nanoparticles for removal of methylene blue dyes
Authors: Isa N , Wan Kamis W Z , Inderan V , Husin N I , Ahmad F N , Bashirom N H , Lockman Z
Published: December 2019

Silver nanoparticles (AgNPs) were synthesized by green biological technique utilising kyllinga brevifolia extract (KBE) as reducing agents. The KBE was also found to be a good capping as well as stabilizing agent. The size, shape and dispersion of AgNPs were evaluated and compared with the results from the literature survey. The TEM image showed that KBE-driven AgNPs have quasi-spherical shape are highly dispersed with an average particle size ~17.64 nm. The catalytic activity of KBE-driven AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analysed using UV-vis spectroscopy. The MB removal was achieved 100% at pH 8-10. The efficient removal is proposed to be due to the process of reduction via electron relay effect.
Waste plastic fiber as stabilizer in sub-base sand layer for road construction project
Authors: Abdul Majid M R , Harahap M I P , Hassan S H , Nazmi Rosli M A , Zulfairul Z
Published: December 2019

Pollution dilemma due to plastic bottle waste disposal and buildup is a growing and persistent problem in Malaysia. Clearly, innovate use of such wastes through recycling application in engineering must be found. This research was aimed to utilize waste plastic fiber in problematic road construction project that can be both economical and environmentally friendly. Additionally, it has the potency to increase the mechanical strength of commercial sand through the CBR parameter of the road pavement sub-grades. The sand usually possesses low CBR value which on its own may not be entirely suitable for the road construction works unless additive or stabilizer was added. In this study, the specimen used as additive to the sand involved 5 mm wide × 10 mm wide plastic fiber which was obtained from shredded waste plastic bottles. There were several percentage of waste plastic fibers that had considered in the research apart from the control specimen namely at 0 %, 0.1% and 0.5% in conjunction with 5 % cement and water at optimum moisture content level. Several laboratory tests had been prescribed namely characterization tests, compressibility test and CBR test. The result shows that as the percentage of waste plastic fiber increased, the CBR value also increased indicating positive relationship between the two variables.
Nanofluid-filled heat pipes in managing the temperature of EV lithium-ion batteries
Authors: Nasir F M , Abdullah M Z , Majid M F M A , Ismail M A
Published: December 2019

This paper presents the numerical study on the usage of Al2O3 nanofluid-filled heat pipes in controlling the temperature of lithium-ion batteries, specifically for the application in powering the electric vehicle (EV). The heat pipes thermal management system (HPTMS) was modelled as a solid continuum body with high equivalent thermal conductivity. Thermal resistance network model was used to determine the equivalent thermal conductivity. The effect of heat inputs and the nanoparticle volume concentration on the performance of the HPTMS were studied. The simulation results were validated against previous experimental works and showed good agreement with each other. Results also indicate that by using 1.5%vol Al2O3 as the working fluid in the heat pipes, the battery surface temperature and the total thermal resistance can be reduced by as much as 4.44°C (7.28%) and 15%, respectively.
Effect of different fibre reinforcement type to the shear strength of soft soil at varying moisture condition
Authors: Abdullah N H H , Aziz N H A , Jaafar F F , Osman N M , Ahmad A , Hamid S A
Published: December 2019

The utilisation of discrete fibre in the soil reinforcement technique to overcome the problems of soft compressible soil are investigated in this paper. Two different type of fibre is used herein, i.e. polypropylene and plastic fibre. Shear strength of soils is highly affected by moisture conditions. In practice, a laboratory investigation conducted to determine the shear strength of soil is prepared at optimum moisture content. However, at field conditions, the actual water content may vary. The effect of moisture variation with respect to optimum moisture content is investigated in this study. Unconfined Compressive Strength Test was carried out to study the effect of fibre type, fibre content and soil moisture condition. The test results indicated that the reinforced soil using polypropylene fibre provides higher strength increment compared to plastic fibre. The highest strength was achieved at 0.15% additional of polypropylene fibre in the dry moisture condition.
Release of encapsulated citronella oil in Tween 80 solution
Authors: Ariff S B M , Jai J , Jamaludin S K , Ibrahim N
Published: December 2019

Microencapsulation is a technique in which small particles are enclosed by a coating wall. Microencapsulation has been widely used in applications such as the controllable release of essential oils and improvement of the stability of the core substances and many other fields. Volatiles liquids and solids are easily damaged during long term use, due to their external environment. This leads to degradation and loss of function. In preventing this drawback, encapsulation of essential oils by embedding them into polymer wall has been introduced. In this study, citronella oil (CO) encapsulated by gelatin-chitosan was prepared by complex coacervation technique. Report on release study of encapsulated CO and its applications in floor cleaning solution is very limited. Hence, release rate and release mechanism of the microcapsules in simulated floor cleaning solution (Tween 80 solution) were investigated. Morphology of the microcapsules was determined through optical microscope. The release of CO was observed through the formation of rupture on the spherical microcapsule. The release rate of encapsulated CO increases with the increase of temperature from 25°C to 75°C. The release mechanism of the CO, based on Fick’s law was classified as following the Korsmeyer-Peppas controlled release model of super case II, whereby the release is due to wall erosion.
Characterization of food waste and empty fruit bunches (EFB) for anaerobic digestion application
Authors: Hamzah M A A , Alias A B , Him N R N , Rashid Z A , Ghani W A W A K
Published: December 2019

Food waste (FW) and empty fruit bunches (EFB) possess a great potential to be used for anaerobic digestion process, as these two biomasses are rich in biodegradable organic matter, in which its contents play an important role in determining the efficiency of the digestion process. In this study, the elemental compositions, nutrients content, and lignocellulosic content of Malaysian FW and EFB were determined by running several procedures and were compared to past literatures which also used similar feedstock for anaerobic digestion; to determine whether the biomasses used in this study could lead to better performance of anaerobic digestion. Elemental analysis of the FW showed that the C/N ratio ranged from 4.45 to 15.45, within the optimum range as defined by past studies. For EFB, the C/N ratio was similar to FW, making EFB suitable to be mixed with FW for optimum anaerobic digestion conditions. Nutrients analysis of the FW showed that FW Types A and D, rice waste and food waste mixture respectively, possessed the most balanced carbohydrates, proteins and lipids nutrients for optimum digestion. Lignocellulosic analysis of the EFB also proved that its contents were favourable to be used in anaerobic digestion; high cellulose content, low lignin content.
In silico analysis of essential and non-homologous proteins in Salmonella typhimurium biofilm
Authors: Othman N A , Yahya M F Z R
Published: December 2019

Salmonella typhimurium is a Gram negative pathogen that commonly causes severe gastroenteritis. It is resistant to a wide range of antibiotics and is able to form biofilm on both biotic and abiotic surfaces. To date, essential and non-homologous proteins in S. typhimurium biofilm remain not well investigated. Therefore, the present work was performed to analyze essential and non-homologous proteins in S. typhimurium biofilm using a combination of one-dimensional SDS-PAGE, HPLC - ESI - QTOF and bioinformatics. Results demonstrated that seven major protein bands (78.1 kDa, 51.2 kDa, 41.5 kDa, 37.3 kDa, 35.1 kDa, 27.6 kDa, and 25.4 kDa) were present in whole-cell protein extract of S. typhimurium biofilm. A total of 75 proteins were successfully identified from both 25.4 kDa and 51.2 kDa protein bands. Approximately 54.67% of QTOF-identified whole-cell proteins were found to be essential to the survival of S. typhimurium biofilm and were non-homologous to human proteome. Majority of essential and non-homologous S. typhimurium biofilm proteins were associated with transport and protein synthesis. The findings from the present work may be useful for development of novel antibiofilm agent.
Mechanical and corrosion properties of Mg-Zn/HAP/Al2O3hybrid composite
Authors: Ahmad F N , Rashid N , Zuhailawati H
Published: December 2019

The effect of HAP and Al2O3composition with constant of ceramic content of 15 wt. % on mechanical properties, microstructure, and corrosion behavior of degradable Mg-Zn/HAP/Al2O3hybrid composite developed by powder metallurgy method were investigated. The microstructure was analyzed using an optical microscope and scanning electronic microscope while mechanical properties were evaluated for density and compression strength. Meanwhile, corrosion behavior in Hank Balanced salt solution (HBSS) was studied for 4 h. The addition of HAP and Al2O3particles has improved the mechanical properties and corrosion properties of Mg-Zn alloy. The results show that 15 wt. % Al2O3(without HAP) shows the higher density, hardness, and compression. However, the composite consisted of 10 wt. % HAP with 5 wt. % Al2O3shows the lower corrosion rate.
Theoretical investigations of the structural and electronic properties of boron nitride clusters: DFT comparison of several basis sets
Authors: Toh P L , Wang S M
Published: December 2019

In this present study, Density Functional Theory (DFT) calculations were conducted to study the structural and electronic properties of (1,1), (2,2), (3,3), and (4,4) Boron Nitride (BN) systems. Geometry optimization calculations were carried out to find the stability of BN cluster models. The obtained structural geometries are consistent with that obtained in the previous reported results [1]. The total energies increase when the cluster sizes of BNs increase. For each cluster size of BN, the four total energy values obtained from B3LYP level of theory with employing the basis sets of 6-31++G, 6-31++G**, 6-311++G, and 6-311++G** are close to each. Moreover, our computations revealed that the gap energy values of HOMO-LUMOs in the BN cluster structures have been decreased by following its structure and dimensionality. The calculated HOMO-LUMO gaps are 5.99 eV - 7.68 eV in this study. For the diagrams of molecular electrostatic potential (MEP) surfaces, the regions around the N atoms at the center hold the highest electronegative potential, which can attract more electrons in the BN systems. With a Mulliken population analysis (MPA) scheme, all the boron atoms possess the positive charges, whereas the negative charges were found on the nitrogen atom in the BN systems.
Fabrication of TiO2-CuInS2 nanocomposite on ITO substrate via liquid carbon dioxide coating
Authors: Nursanto E B , Min B K , Kim J
Published: December 2019

TiO2-CuInS2 is one of the promising materials for 3D nanocomposite solar cells. To utilize for 3D nanocomposite solar cells, TiO2-CuInS2 should well deposited onto transparent conducting oxide such as indium doped tin oxide (ITO). High pressure coating with liquid carbondioxide (l-CO2) was successfully deposited TiO2-metals chalcogenide onto ITO substrate. Further heat treatment (oxidation and sulfurization) lead the formation of CuInS2 from metals chalcogenide deposited on the mesoporous TiO2. The formation of CuInS2 on the was confirmed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and Raman spectroscopy. The atomic ratios of deposited CuInS2 were nearly stoichiometric after sulfurization. The crystal growths of CuInS2 were controlled by adjusting the number of coating cycles.
Mathematical modelling of drying kinetics of oven dried Hibiscus Sabdariffa seed
Authors: Ismail N F , Mat Nawi H N , Zainuddin N
Published: December 2019

Hibiscus sabdariffa or Roselle seed is an agricultural product which possesses a large amount of nutritional content that could be useful in wide application. Drying process can be helpful to conserve the seeds for long storage periods. For this reason, the drying behavior of Roselle seeds was investigated using laboratory oven at various drying temperatures (35, 45, 55, 60 and 65°C). It is found that the drying process of the Roselle seeds consists of constant rate and mostly falling rate period at where the moisture content of Roselle seed decreases as time goes. Adequately suitable drying temperature is found to be 65°C with the drying time of 240 minutes. The drying behavior of Roselle seeds is further understood through the drying kinetics of the Roselle seeds. Five empirical mathematical models were selected to describe and compare the drying characteristics of Roselle seeds at respective drying temperatures. Drying rate constants, coefficients and statistical parameters were determined by non-linear regression analysis, and therefore, the diffusion approach model was selected as the best model with R value obtained is 0.999 while MBE, RMSE and χ2 values of 2.37E-04, 0.01335 and 0.007794 respectively.
Life cycle assessment approach to sustainable sewage sludge management for water pollution control
Authors: Mu’azu N D , Essa M H , Aga O , Jarrah N
Published: December 2019

Increase in population growth coupled with industrialization, urbanization and requirements for implementation of stricter effluent discharge standards, sludge from wastewater treatment plants (WWTP) is expected to be produced in a continually increasing amount globally. The management of the huge volume of sludge generation becomes an integral component of environmental sustainability. Therefore, the need for environmentally friendly approach to sludge management strategy couldn’t be overemphasized. This paper proposes a rational and more sustainable approach directed towards devising means to solve the problem of the huge amount of WWTPs sludge by converting it to granular activated carbon (GAC) for utilization in water pollution control via incorporating Life Cycle Assessment (LCA). The paper reviews the various approaches and techniques for drying, pyrolysis and activation techniques and the best operating conditions for sludge based activated carbon (SBAC) for optimal pollution control. Based on that, a holistic decision making tool was recommended which incorporates major production, treatment and disposal options for each stage using Life Cycle Assessment (LCA) approach (from-cradle-to-grave), from which wide range of alternative scenarios will be generated vis-à-vis water pollution control efficacy in relation to environmental, cost as well as energy implications.
Removal zinc ions from contaminated soil using biodegradable polyaspartate via soil washing process
Authors: Mu’azu N D , Essa M H , Haladu S A , Ali S A , Jarrah N , Zubair M , Mohamed I A
Published: December 2019

This work reports the potential use of polyaspartate (PASP) synthesized from L-aspartic acid via a newly modified thermal procedure as a soil washing chelating agent for Zn ions removal from contaminated-soil. Response surface methodology (RSM) via faced central composite design was employed for evaluating and optimizing the influence of operational parameters. RSM response models developed describe well the Zn removal efficiency with high R2 (> 0.994-0.998; p-values < 0.001) and in-significant lack of fit. Zn washing efficiency was found to increase with increase in Zn initial concentration and decrease in PASP/soil ratio. The relative contribution of the operating conditions on Zn removal follows the order; PASP/soil ratio, initial heavy metal concentration, PASP concentration, initial pH and extraction time. Optimal conditions occurred at 500 mg/kg Zn concentration, 36 mM PASP concentration, 10 polymer-soil ratio, pH 4 and 6 hours retention time when Zn ions removal was 39% with most efficient PASP utilization. Although, 100% removal of Zn was achieved at low Zn concentration (100 mg/kg), yet, more amount of the PASP was needed. These results demonstrated the feasibility of effective utilization of PASP for decontamination of Zn ions polluted soils.
The time dependences of the main properties of the vortex loops just after reconnection in superfluid helium
Authors: Andryushchenko V A , Kondaurova L P
Published: December 2019

We investigate a single vortex reconnection event in superfluid helium at zero temperature, when mutual friction is absent, and at 1.9 K temperature, when mutual friction essentially changes the evolution of lines. The vortex filament method with full Biot-Savart equation is used for numerical investigation of the time dependences of the main properties of the vortex loops just after reconnection. In this paper, we present the obtained dependencies of the average curvature of the loop, Lamb momentum, angular momentum, and energy from time. The effect of mutual friction force and initial conditions on these properties is studied.
Features of convective heat transfer in mixed convection regimes in the Czochralski method with different effects of buoyancy forces and thermocapillary effect
Authors: Berdnikov V S , Vinokurov V V , Vinokurov V A
Published: December 2019

The influence of the height of the melt layer on the boundary of the transition from stationary flow and heat exchange to non-stationary regimes for given values of Grashof, Marangoni and Reynolds numbers is investigated. The hydrodynamics, local and integral heat transfer were studied at the value of the Prandtl number 16. At the values of the Prandtl number 10.78; 16 and 45.6, integral heat transfer was studied at a fixed height of the melt layer with increasing Reynolds numbers.
Dynamics of fluidic oscillator jet: LES study
Authors: Dauengauer E I , Mullyadzhanov R I
Published: December 2019

We study a turbulent jet generated by a fluidic oscillator using Large-eddy simulations in a range of Reynolds numbers Red
= 3000−30000. The device represents Φ-shaped configuration providing a strongly unsteady flow due to periodic oscillations based on the Coanda effect. Several simulation results are presented for a mesh convergence study, the analysis of the time-averaged statistics as well as the oscillation frequency against Red
.
The influence of high degree of turbulence on the near wake of the streamlined cylinder
Authors: Dobroselsky K G
Published: December 2019

A method for obtaining high degree of water flow turbulence using semi-cylindrical inserts is shown. The degree of longitudinal turbulence in the flow core of about 20% was obtained under the conditions of the limited size of the working section of the hydrodynamic stand and small overpressure. The PIV method was used to obtain the average characteristics of the near wake behind the cylinder, streamlined by weakly and strongly turbulized flow in the subcritical region. The resulting size of the vortex zone behind the cylinder in the flow with high degree of turbulence is much smaller than in the case of weak turbulence, which is similar to the flow with effective Reynolds number in the region of critical numbers, where the resistance drops sharply.
Numerical optimization of hydrogen microwave plasma reactor for diamond film deposition
Authors: Hrebtov M Yu , Bobrov M S
Published: December 2019

We present the results of optimization of microwave plasma generation in a prototypical diamond film deposition device by means of numerical simulation. The modification of the device was done by changing the shape of microwave resonant chamber, where the plasma generation occurs, in a way to focus the discharge near the outlet nozzle. The best results were obtained for a configuration with an addition of a conducting rod located on the axis of the chamber. This modified configuration provided a two orders of magnitude increase in electron number density near the nozzle exit and about 10 time increase (up to 5%) in dissociation degree of hydrogen molecules.
Investigation of the finite size core helical vortex filament moving in cylindrical channel
Authors: Kashkarova M V , Kuibin P A , Kravtsova A Yu
Published: December 2019

A mathematical analysis of the problem on finding the shape of the core of an equilibrium helical vortex moving in a cylindrical tube has been carried out. Within the core, the vorticity was considered constant. The vorticity distribution was approximated by the Heaviside function. Integral equation for the vortex core boundary and stream function is formulated. An approximate solution on the stream function is found for the case of a circular section of the vortex core. An algorithm developed for the vortex ring [2] is adopted for solution of the problem under consideration.
The heat transfer of round impinging jets
Authors: Lemanov V V , Terekhov V V , Terekhov V I
Published: December 2019

Heat transfer of round impinging jets has been investigated in a wide range of Reynolds numbers (Re=40-21000). A jet flowing out of a profiled nozzle and a long tube at a constant wall temperature and at a distance to the obstacle h/d=1-20 was studied. In experiments at Re<3000 for an outflow from the tube, a noticeable increase in heat transfer by 200-400% is observed, compared with the case when the jet flows out of the nozzle. At Re>3000, the difference in heat transfer for the two variants of jet formation (from the tube and from the nozzle) decreases asymptotically. For laminar and turbulent flow modes, the results of numerical calculations are consistent with the experimental data.
Microstructure of flow in a channel with low-profile spanwise ribs
Authors: Mikheev N I , Dushin N S , Dushina O A
Published: December 2019

The paper presents the experimental data on velocity fluctuation spectra and reattachment lengths observed in turbulent flows past low-profile elements of discrete roughness mounted on the wall. The discrete roughness elements were shaped as semicircular spanwise ribs with the height of 2% of the hydraulic diameter of the channel. It has been revealed that such ribs make the velocity fluctuations increase manifold at the height of rib tops in the range of non-dimensional frequency St=0.6-1.2 that favors the reattachment length reduction and heat transfer augmentation.
Flow structure behind a spanwise rib in channels of different geometry at moderate Reynolds numbers
Authors: Molochnikov V M , Mazo A B , Maluykov A V , Kalinin E I
Published: December 2019

Experimental study of laminar-turbulent transition in a rectangular channel with a semicircular rib has been carried out. The study comprised the flow visualization as well as direct numerical simulation of some flow configurations. The paper investigates the effect of the channel geometry (width and height), aspect ratio of the rib and blockage ratio on the mechanisms of transition to turbulence, formation of large vortical structures in the mixing layer behind the rib and on the critical Reynolds number at which the transition to turbulence occurs.
DNS of heat transfer of the flow over a cylinder at Re = 200 and 1000
Authors: Palkin E , Ryzhenkov V , Mullyadzhanov R
Published: December 2019

We perform Direct numerical simulations of the flow over a cylinder to study the influence of the thermal boundary conditions on the Nusselt number distribution. The results show very good agreement with some data from the literature. The total Nusselt number for the constant heat flux (CHF) boundary condition is higher for some 15% than for the constant wall temperature (CWT) condition for both Re < 200 and 1000.
Modeling the closed circulation of thermal water
Authors: Pen’kovskii V I , Korsakova N K
Published: December 2019

Two schemes of closed circulation of thermal waters are considered. The first scheme is filtration in a single stratum. In the second scheme, the flow in a formation with a weakly permeable bottom is considered. The effective for designers formulas are obtained. The thermal formation model is used in the form of a heterogeneous structure consisting of two embedding continuums.
Generalized correlations for predicting heat transfer and friction factor of turbulent flow in tubes with inner helical ribs
Authors: Popov I A , Skrypnik A N , Schelchkov A V
Published: December 2019

Generalized correlations for predicting heat transfer and pressure drop for turbulent flow of Newtonian fluid through tubes with inner helical ribs are presented. A comparison with existing correlations in the literature shows that revealed correlations allow decreasing the data deviation and cover the wide ranges of working fluids, operational conditions, and different dimensions of helical ribs.
The asymmetry of the recirculation zone of the annular jet with different diameter ratio
Authors: Ryzhenkov V O , Abdurakipov S S , Mullyadzhanov R I
Published: December 2019

We performed direct numerical simulations of the annular turbulent jet flow for the Reynolds number based on the bulk velocity inside the nozzle and its outer diameter Re = 8900 with three different values of the inner-to-outer diameter ratio a = d / D = 0.3, 0.5, 0.7. The size of the reversal flow region, the fluctuation level and mixing rate increase with the increase of the diameter ratio. For all the cases of geometry parameters the symmetry breaking phenomenon was detected. The degree of asymmetry increases with the increase of the diameter ratio resulting in the displacement of the global stagnation points form the axis of symmetry and the deflection of the averaged streamlines from the jet axis.
The influence of tabs on fluid dynamic measurements downstream of a backward-facing step
Authors: Terekhov V I , Sharov K A , Smulsky Ya J , Dyachenko A Yu
Published: December 2019

PIV-method was used to study the flow behind a backward-facing step in the presence of tabs for the Reynolds number Re=4000. The studied tabs had rectangular shape and a height of 6 mm, and were installed with a step of 25 and 50 mm. The tabs, depending on the step, had a different effect on velocity profile. At the tab location, the profiles of the average longitudinal and transverse velocity were strongly deformed and became similar to the behaviour behind the solid rib. In the area between the tabs due to the adjacent pair of tab-induced vortices, the attachment of the mixing layer occurred earlier than at streamlining of a smooth step. The recirculation area was noticeably reduced for tabs with spacing of 50 mm, and at the same time, with a reduction in the distance between them to 25 mm, the size of this zone increased.
Evolution of a localized wave packet in the boundary layer of the swept wing at M = 2
Authors: Yatskikh A A , Ermolaev Y G , Smorodsky B V , Panina A V , Semionov N V , Kosinov A D
Published: December 2019

The evolution of an artificial localized wave packet in a supersonic boundary layer of a swept wing is experimentally investigated at Mach number M = 2. The wave characteristics of the development of disturbances at various frequencies are determined. The growth increments of the most increasing modes of the wave packet are estimated. Comparison with the results of calculations based on the linear theory of stability is carried out.
Analysis of eigenmodes in a swirling jet and flame: 3D PIV and PLIF study
Authors: Abdurakipov S , Lobasov A , Chikishev L , Dulin V
Published: December 2019

The existence of spiral structures was directly confirmed experimentally on the basis of 3D Particle Image Velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements both in a strongly swirling non-reacting jet and in a fuel-lean premixed methane-air flame. Flows were characterized by the presence of vortex breakdown and precession of the vortex core. The differences in magnitude and spatial distribution of flow eigenmodes with distance from the nozzle are analyzed by using Proper Orthogonal Decomposition (POD) based on Spatial Fourier Transform over azimuthal coordinate. The analysis of flow eigenmodes reveal that for a high-swirl isothermal jet, the vortex core co-existed with the pair of counter-rotating helical vortices, which were located in outer shear layer and inside the recirculation zone. This double-vortex helical structure was also detected in a swirling flame, but its magnitude was suppressed compared with isothermal flow. It was determined that the change in the shape of the chemical reaction area was associated with two types of large-scale coherent structures: nearly axisymmetric mode m = 0 of the flame front deformation, presumably due to the effect of buoyancy forces on the combustion products, and the quasi-solid rotation of the asymmetric global mode |m| = 1 in the form of double-vortex structure due to precession of the swirling flow. It was shown that the energy of the axisymmetric mode m = 0 in a reacting jet increased downstream by almost 10 %, unlike other modes, whose energy was only diminished.
Numerical simulation of liquid hydrocarbon fuel burning in a direct-flow evaporation burner in a jet of superheated steam
Authors: Dekterev Ar A , Minakov A V , Anufriev I S
Published: December 2019

In this work, the process of diesel fuel combustion in a laboratory sample of an original evaporation-type burner with superheated steam supply to the reaction zone was investigated by numerical simulation. Fuel burning in such a burner occurs in a steam jet flowing through the nozzle. In the framework of research, a mathematical model was developed, the influence of various models of turbulence, approaches to simulation of combustion, and response schemes were investigated.
Numerical simulation of transient mixing and ignition processes in a supersonic combustor chamber
Authors: Zakharova Yu V , Fedorova N N , Goldfeld M A , Vankova O S
Published: December 2019

The paper presents the results of a numerical and experimental study of the processes of mixing and combustion in a model combustion chamber under conditions of multi-jet injection of hydrogen into supersonic (M = 4) external flow. Numerical simulation is performed for the conditions of experiments conducted in a high-enthalpy short-duration facility IT-302M. Joint analysis of experimental and calculated data allows us to obtain new data on the structure of the flow and describe the process of ignition and flame propagation through the channel of the combustion chamber under the conditions of unsteady (falling) input conditions.
Combustion of round hydrogen microjet in a cocurrent air flow
Authors: Kozlov V V , Grek G R , Katasonov M M , Litvinenko M V , Litvinenko Yu A , Tambovtsev A S , Shmakov A G
Published: December 2019

Experimental data on combustion of a round hydrogen microjet in a cocurrent coaxial air jet are presented. As is found, the combustion of microjet is dominated by the generation of “bottleneck-flame region” that is in agreement with our previous observations on the diffusion combustion of subsonic hydrogen microjets. Transformation of the spherical “bottleneck-flame region” to a cylindrical one is observed. At supersonic combustion of the round hydrogen microjet, supersonic cells are generated both in the microjet and in the cocurrent coaxial air flow. A feature of the combustion process is the flame lift-off from the nozzle exit.
Numerical simulation of premixed methane/air and synthesis gas/air flames for turbulence swirling jet
Authors: Lobasov A S , Dekterev Ar A , Minakov A V
Published: December 2019

This paper reports on the investigation of combustion features of turbulent swirling methane/air and synthesis gas/air flames via using modern CFD-approaches. For methane/air mixture the equivalence ratio Φ was 0.7 which is near to the lean blow off limit. Two regimes with 1:1 and 1:2 ratios of hydrogen and carbon monoxide in the fuel mixture have been considered for synthesis gas combustion. For validation of numerical models, the reliable experimental data has been used. It is found that LES approach demonstrates good agreement with the experimental data. Comparison between methane/air and synthesis gas/air flames demonstrates that in the latter case the size of recirculation zone and the flame temperature are decreasing. But, addition of carbon monoxide in synthesis gas/air mixture leads to flame temperature rise.
Gradient ceramic structures formation from an impact jet of vapors of organometallic compounds flowing onto the hot barrier
Authors: Lukashov V , Abdrakhmanov R , Vasilieva I , Igumenov I
Published: December 2019

Chemical vapor deposition of coatings (MO CVD) using volatile organometallic compounds is considered. The results of the analysis of coating parameters by X-ray diffraction methods, microscopic visualization and differential dissolution confirm the possibility of controlling the composition and structure of the coatings by varying the parameters of the deposition process. The obtained data laid the foundations for the physicochemical process of forming thermal coatings with given functional characteristics.
Regimes of filtrational gas combustion in a cylindrical annular burner with radiation heat transfer
Authors: Palesskiy F S , Minaev S S
Published: December 2019

A problem of premixed filtrational gas combustion in a cylindrical annular burner has been solved in the frame of one-dimensional diffusion-thermal model taking into account internal radiative heat transfer in porous burner and radiative heat flux emitted by internal layers of porous material. Two different stationary combustion regimes are detected under the same values of gas flow rate. It was shown that stationary flame radius depends on the initial ignition conditions. Solid and gas temperature characteristics depending on flame radius and gas flow rate are studied. Estimation of the burner radiation efficiency is carried out. Significant difference between temperature characteristics of gas and solid phases and burner radiation efficiency for different combustion regimes are shown.
On combustion regimes of syngas-air and methane-air lean flames for swirl-stabilized burners
Authors: Tolstoguzov R V , Sharaborin D K
Published: December 2019

This work presents result of visualisation of the characteristic combustion regimes of methane-air and syngas-air swirl-stabilized flames for an unconfined premixed burner (Re = 5000) and non-premixed combustion chamber (Re = 30000). Equivalence ratios were selected to have nearly equal values of the laminar flame propagation speed for the methane/air and syngas/air flames. Visualization for the premixed combustion for the model swirl burner revealed a similar shape of the flames for all mixtures. In contrast, during combustion of methane and syngas in the combustion chamber in the case of combustion in the combustion chamber, these differences in parameters cause completely visually diverse combustion modes.
Three-dimensional simulation of gas injection into an open fluid-filled pipe region
Authors: Alekseev M V , Vozhakov I S , Lezhnin S I , Pribaturin N A
Published: December 2019

Three-dimensional simulation of air injection into a liquid (water, liquid lead) at large pressure drops in a three-dimensional formulation has been carried out. A significant difference in the formation of the air volume form at injection of water and liquid lead is shown. The instability of the interfacial surface in the form of annular waves and axial cavity on the upper surface of the slug has been revealed in three-dimensional calculation. For the three-dimensional case the gas-dynamic structure of the compression jumps and the Mach disk is found to be more pronounced for the supersonic underexpanded jet inside the slug.
Influence of flow conditions on compression surfaces of hypersonic inlet on characteristics of boundary layer bleed
Authors: Goldfeld M A
Published: December 2019

The paper presents the results of analytical and experimental study of the bleed coefficient at flight Mach numbers from 3 to 7. For the calculation, a calculation model with a fixed exit in the supercritical bleed mode was used, which allows varying the bleed air mass depending on flow conditions and parameter of the bleed system. The measurement of the bleed flow coefficients were performed for three bleed configurations in a wind tunnel at local Mach numbers in front of the bleed area from 2.5 to 5.96. The model had a long forebody, so that before the bleed area there was a thick boundary layer. As a result, new experimental data on bleed coefficient and its general dependence on the Mach number of up to 6 and the bleed angles of 90° and 45° were obtained. It is revealed that at an increase in the local Mach number, the tendency towards a decrease in the bleed coefficient is observed, and this tendency becomes more intensive with a decrease in the bleed channel inclination. These data were used to evaluate known analytical calculation method to determine the characteristics of bleed systems at hypersonic flow velocity.
Effect of conjugate heat transfer on the side and horizontal walls on the structure of convective flow in the Rayleigh-Benard convection mode
Authors: Danilov N I , Mitin K A , Berdnikov V S
Published: December 2019

Rayleigh-Benard convection in rectangular cavities with different relative size with walls of finite thermal conductivity is studied numerically in a two-dimensional conjugate formulation. The influence of relative cavity sizes on the spatial shape and evolution of convective flows with increasing Rayleigh numbers is investigated. Velocity and temperature fields in the liquid, temperature fields, temperature gradients and heat fluxes in solid walls are calculated. The effect of conjugate heat transfer with walls of finite thermal conductivity on the spatial shape and local characteristics of convective heat transfer is studied.
Numerical study of the cuttings transport by drilling mud in horizontal directional well
Authors: Zhigarev V A , Minakov A V , Neverov A L , Pryazhnikov M I
Published: December 2019

The results of numerical simulation of cutting by mud are providing in this article. The influence of flow rate on the values of pressure drop and cutting removal was studied.
Temperature distribution in a cylindrical container with crude oil after ultrasonic treatment
Authors: Kadyirov A I , Karaeva J V , Makarushkin D V
Published: December 2019

The distribution of oil temperature in a cylindrical container is researched experimentally after ultrasonic treatment with frequency 22 kHz. Samples of crude oil were considered as a working fluid with effective viscosity 3-4 Pa*s and 0.029-0.03 Pa*s. The capacity of the ultrasonic device varied from 80 to 160 W. Temperature gradient is obtained over the height of the container for more viscous oil.
Hydraulic and gas-dynamic models of a steam-water mixture flow in a granular bed
Authors: Tairov E A , Khan P V
Published: December 2019

The paper presents a comparative analysis of the hydraulic and gas-dynamic models of a steam-water mixture flow through a granular bed. The analysis is carried out using experimental data obtained at an inlet pressure of 0.6 - 15.5 MPa, flow quality of 0.002 - 0.3, and mass velocity through a cross-section of a packed bed from 44.5 to 410 kg/(m2s). In the hydraulic model, with a view to improving the accuracy, the algebraic calculation of an average pressure is replaced with numerical integration over the bed height. In the gas-dynamic model, which allows analytical integration, refined constitutive relations are proposed. An analysis of the obtained results indicates that the gas-dynamic model provides a good description of experimental data, whereas the hydraulic model leads to a considerable error in calculation in the case of large relative pressure drops.
Model of reduced kinetics for describing heterogeneous detonation in gas particle mixtures with non-uniform concentration distribution
Authors: Khmel T A , Tolkacheva S I
Published: December 2019

A simple model of reduced kinetics is proposed to describe the detonation combustion of gas particle suspensions with a non-uniform concentration distribution. The model is verified on the basis of empirical data on the dependence of the detonation velocity on the particle loading. The model constants for the substoichiometric and superstoichiometric suspensions of aluminum particles in oxygen are determined. The formation of suboxides and incomplete combustion of aluminum are taken into account integrally. Examples of numerical simulation of the Chapman-Jouguet detonation propagation in mixtures with longitudinal concentration gradients and cellular detonation in lean and superstoichiometric mixtures of aluminum and oxygen are presented.
A small-mode model for spatial regimes on a freely falling liquid film
Authors: Tsvelodub O Yu
Published: December 2019

Spatial wave modes of a viscous liquid film freely flowing down a vertical wall are considered. In the case of small Reynolds numbers the problem is reduced to considering solutions of a nonlinear equation for the film thickness deviation from the undisturbed level. It was used to obtain a model system of equations, describing spatially periodic solutions with wave numbers lying in the vicinity of special resonance points and symmetric in the transverse coordinate. Several solutions for this system are provided.
Contact angle dynamics for evaporating droplet on contrast nano-structured surface
Authors: Bochkareva E M , Lei M K , Miskiv N B , Starinsky S V , Terekhov V V
Published: December 2019

In this work, a series of experiments was carried out to study the evaporation rate of sessile and suspended droplets. The basic geometric characteristics of an evaporating drop from a biphilic surface are investigated. Evaporation dynamics data have been obtained, showing that evaporation from an inverted substrate is faster than evaporation of a sessile drop.
Features of heat transfer during the evaporation of a drop of nanofluid
Authors: Bochkareva E M , Miskiv N B , Nazarov A D
Published: December 2019

In the present work, experimental studies of factors affecting heat and mass transfer during the evaporation of droplets of nanofluids with SiO2 nanoparticles (base liquid - water) were carried out in a wide range of mass concentrations and initial environmental parameters (temperature and flow rate). According to the results of the study, it was found that the effect of nanoparticles under forced convection depends on the initial environmental conditions.
Vacuum freezing of clay porous material
Authors: Fedoseev A V , Salnikov M V , Demin N A , Sukhinin G I , Yarygin I V , Prikhodko V G , Novopashin S A
Published: December 2019

The results of experimental measurements of a temperature distribution in a clay layer of finite thickness for a vacuum drying process are demonstrated. The results of the experiment were compared with the results of the numerical model. An incomplete correspondence between two approaches was obtained. The effect of width of the clay layer on the course of the vacuum drying process is shown.
The effect of evaporation on a horizontal liquid film rupture
Authors: Kochkin D Y
Published: December 2019

This work is devoted to the experimental study of the rupture of a horizontal liquid layer placed on a stainless steel substrate non-uniformly heated from bellow. The goal of this work is to study the dynamics of film deformation and to determine the effect of evaporation and film thickness on the rupture. The film thickness and the deformation profiles were measured using the confocal Micro-Epsilon system with a positioning system. Liquid film initial thickness varied from 300 to 850 μm.
The experimental investigation of the evaporation rate of nanofluids based on different fluids
Authors: Lobasov A S , Minakov A V
Published: December 2019

The evaporation of the nanofluids based on Al2O3 nanoparticles and different fluids was experimentally investigated. The distilled water and isopropyl alcohol were used as base fluids. The average diameter of Al2O3 particles was 100 nm. The investigations of fluids evaporation rates were carried out using the Simultaneous Thermal Analyzer STA 449 C Jupiter (NETZSCH). The investigation of the evaporation rate dependence on the carrier media was carried out. It was found that the average relative evaporation rate of fluids increased, and the time of complete evaporation accordingly decreased with an increase in the volume concentration of nanoparticles. In addition, the absolute value of the evaporation rate was found to significantly depend on the type of base fluid. However, the relative value of the evaporation rate for different base fluids remains approximately the same.