Search

The complex cross-sectional shape of oversized beam blanks and the size effect of ultra-large-section beam blanks create severe issues related to the surface and internal quality of the castings. To ensure quality and control in the production of ultra-large-section beam blanks, a numerical and physical model of molten steel flow in the three-port submerged entrance nozzle (SEN) mould, with section dimensions of 1300 × 510 × 140 mm, was established. This model was created using numerical simulations and NSGA-II genetic algorithm optimisation, and the impact of the casting speed and SEN immersion depth on the mould's flow behaviour was investigated. The results showed that a deeper SEN immersion depth resulted in, a greater impact depth of the molten steel, and the surface flow velocity decreased. Both the impact depth and the surface flow velocity of the molten steel increased with increasing casting speed. The physical simulation and numerical simulation of the molten steel flow form and flow velocity distribution in the mould were in good agreement with each other, thus verifying the accuracy of the numerical simulation. The process parameters derived from this study were all within an appropriate range, which can help to improve the quality of continuously cast beam blanks. This also provides guidance for selecting optimal parameters for actual continuous casting production processes. [ABSTRACT FROM AUTHOR]

Abstract Wash oil is a fraction obtained by the distillation of coal tar and is primarily used for the absorption of light oil from coke oven gas. During operation, the oil undergoes polymerization and loses some components, necessitating the removal of the used oil and its replacement with fresh wash oil. The rheological properties of the studied oils were determined using a Brookfield DV2T rotational controlled-shear rate rheometer. Gas chromatographic analysis, gas chromatography/mass spectrometry, and IR spectroscopy were employed to evaluate the oil’s characteristics. By adding individual components to the wash oil, it was found that these components could be categorized into three groups: viscosity enhancers, viscosity reducers, and non-polar oil substances with medium molecular weight that have no significant effect on viscosity. The addition of relatively polar components with greater molecular weight and a planar, rigid structure leads to an increase in viscosity. Conversely, the incorporation of naphthalene and its methyl homologues, which have lower molecular weights, reduces viscosity by disrupting intermolecular interactions; their lower heats of crystallization also inhibit the formation of structured order in the liquid, further contributing to the reduction in viscosity. The most substantial increase in oil viscosity was observed with the addition of indene-coumarone resins, attributed to their high molecular weight and polymer structure.

To help with designing the drying process, this study investigated the flow behaviour of lactose and protein‐rich reconstituted dairy powders at 25°C and 50°C. Lactose‐rich samples, 50% dried whey (DW) and 60% whey protein concentrate (WPC35) did not follow the Herschel–Bulkley model because of presence of lactose crystals. Reconstituted 50% skim milk powder (SMP) and protein‐rich dairy powders exhibited shear‐thinning behaviour (n < 0.3). With increasing concentration, whey protein concentrate/isolate (WPC80/WPI) and micellar casein concentrate high‐solid dispersions exhibited more shear‐thinning behaviour (n < 0.4). Understanding shear‐thinning behaviour of lactose‐rich and protein‐rich reconstituted dairy powders will provide basis for optimising drying parameters. [ABSTRACT FROM AUTHOR]

Wash oil is a fraction obtained by the distillation of coal tar and is primarily used for the absorption of light oil from coke oven gas. During operation, the oil undergoes polymerization and loses some components, necessitating the removal of the used oil and its replacement with fresh wash oil. The rheological properties of the studied oils were determined using a Brookfield DV2T rotational controlled-shear rate rheometer. Gas chromatographic analysis, gas chromatography/mass spectrometry, and IR spectroscopy were employed to evaluate the oil's characteristics. By adding individual components to the wash oil, it was found that these components could be categorized into three groups: viscosity enhancers, viscosity reducers, and non-polar oil substances with medium molecular weight that have no significant effect on viscosity. The addition of relatively polar components with greater molecular weight and a planar, rigid structure leads to an increase in viscosity. Conversely, the incorporation of naphthalene and its methyl homologues, which have lower molecular weights, reduces viscosity by disrupting intermolecular interactions; their lower heats of crystallization also inhibit the formation of structured order in the liquid, further contributing to the reduction in viscosity. The most substantial increase in oil viscosity was observed with the addition of indene-coumarone resins, attributed to their high molecular weight and polymer structure. [ABSTRACT FROM AUTHOR]

Monel K500 is a high strength, precipitation hardenable, nickel-copper alloy with additions of Al and Ti, having excellent corrosion resistance and ignition resistance to high pressure gaseous oxygen. However, this alloy is highly sensitive to hot workability and is crack prone during hot deformation. This study investigates the effect of hot workability parameters such as temperature, strain rate, and overall strain on the microstructure evolution. The hot deformability of this alloy was studied using isothermal hot compression tests in the temperature range of 850 °C to 1150 °C and at strain rates ranging from 10− 3 to 10 s− 1, using a Gleeble 3800 thermo-mechanical simulator. The flow behaviour was analysed using stress-strain and strain hardening plots. Initial microstructure of the material has as-cast dendritic structure, while microstructural analysis of hot deformed samples revealed gradual reconstitution with increasing temperature and decreasing strain rate. Hot deformed samples showed traces of recrystallized grains and carbides across the matrix at high temperatures and low strain rates. EBSD GROD mapping further elucidates the variation of microstructural features with variation of strain rate. In accordance with the Ziegler instability criterion, processing maps were constructed for a true strain of 0.65, encompassing deformation temperatures between 850 °C and 1150 °C, and strain rates ranging from 0.001 to 10 s− 1. Through an examination of strain rate sensitivity map, processing map and analysis of deformation activation energy, both undesirable (unstable) and potentially favourable (stable) hot deformation parameters were identified. Instability regions in the processing maps were validated with the microstructural features of deformed samples of cast Monel K500 alloy. [ABSTRACT FROM AUTHOR]

The abundant production of little millet in India and having rich nutritional profile, prompting a need for scientific interventions to optimize its utility compare to other primary cereal crops. This study was conducted to examine the effect of atmospheric cold plasma on rheological properties of little millet flour (LMF) using multiple pin reactor. This investigation involved varying voltage levels (10 kV to 20 kV) and durations (10, 20, and 30 min). The study reported linear viscoelastic region, flow behavior studies and changes in storage and loss modulus of LMF suspensions with reference to frequency and temperature. The strain (γ = 0.5%) was taken with in linear viscoelastic (LVE) region. Analysis of shear stress and viscosity in relation to strain provided insights into the flow behavior of the flour suspension. Two mathematical models, namely Herschel Bulkley and Power law equations, were employed to characterize the fluid type. Both models affirmed that LMF suspensions exhibit pseudoplastic behavior. The Herschel Bulkley model demonstrated a robust fit for LMF, with an R2 value exceeding 0.99. During the frequency sweep analysis, both moduli, namely storage modulus and loss modulus, exhibited higher values following plasma treatment compared to the control. Temperature sweep also revealed alterations during both heating and cooling cycles. Finally, the treated little millet flour (LMF) holds potential for diversifying into various new food applications, particularly in the production of pastes and viscous products. [ABSTRACT FROM AUTHOR]

The flow behaviour of AA2060 Al alloy under warm/hot deformation conditions is complicated because of its dependency on strain rates ( ε ˙ ), strain ( ε ), and deformation modes. Thus, it is crucial to reveal and predict the flow behaviours of this alloy at a wide range of temperatures ( T) and ε ˙ using different constitutive models. Firstly, the isothermal tensile tests were carried out via a Gleeble-3800 thermomechanical simulator at a T range of 100, 200, 300, 400, and 500 °C and ε ˙ range of 0.01, 0.1, 1, and 10 s−1 to reveal the warm/hot flow behaviours of AA2060 alloy sheet. Consequently, three phenomenological-based constitutive models (L-MJC, S1-MJC, S2-MJC) and a modified Zerilli–Armstrong (MZA) model representing physically based constitutive models were developed to precisely predict the flow behaviour of AA2060 alloy sheet under a wide range of T and ε ˙ . The predictability of the developed constitutive models was assessed and compared using various statistical parameters, including the correlation coefficient (R), average absolute relative error (AARE), and root mean square error (RMSE). By comparing the results determined from these models and those obtained from experimentations, and confirmed by R, AARE, and RMSE values, it is concluded that the predicted stresses determined from the S2-MJC model align closely with the experimental stresses, demonstrating a remarkable fit compared to the S1-MJC, L-MJC, and MZA models. This is because of the linking impact between softening, the strain rate, and strain hardening in the S2-MJC model. It is widely known that the dislocation process is affected by softening and strain rates. This is attributed to the interactions that occurred between ε and ε ˙ from one side and between ε , ε ˙ , and T from the other side using an extensive set of constants correlating the constitutive components of dynamic recovery and softening mechanisms. [ABSTRACT FROM AUTHOR]

Frafra Potato (FP) is a climate-smart crop facing extinction in the tropical regions of Africa due to inadequate information about its properties. This study determined the physicochemical, functional, and rheological characteristics of flours from ten FP accessions to gauge their suitability for culinary purposes. The flour yield from FP tubers ranged from 59.3 % (E134) to 69.3 % (E111). While FP flours (FPF) exhibited consistent colour across accessions, variations in paste clarity were noted, ranging from 5.2 % (E145 and Maa-Lana) to 8.6 % (WAAPP). The least gelation concentration varied from 8 % (WAAPP) to 12 % (E 82, 111, 132, 134, 145). Released accessions showed higher protein and ash content than unreleased ones. Mineral composition differed significantly among accessions, including iron, calcium, zinc, and phosphorus, each with varying bioavailability percentages. Vitamin A content also varied across accessions. Proteins common in tuber crops, such as lipoxygenase, patatin, sporamin, tarin, and protease inhibitors (Bowman-Birk PIs), were identified in FPF. Amino acid analysis revealed nineteen amino acids, including seven essentials. FPF characteristics included a bulk density of 0.9 g/ml, oil and water binding capacities of 3 g/g and 1.3 g/g respectively, a pH of 6.4, and titratable acidity of 0.5. All FP flours displayed standard non-Newtonian behaviour, exhibiting pseudoplastic properties. They also showed a type II sigmoidal sorption curve, indicating increased equilibrium moisture content with higher water activity. Moisture sorption studies predicted a safe storage maximum allowable moisture content. These findings have practical implications for flour packaging and storage. The study underscores the culinary potential of Frafra potato and its role in addressing food and nutrition security in Ghana and Sub-Saharan Africa.

The turbulent flow developed underneath a scaled high-speed train of six coaches featured with both conventional and articulated bogies is investigated based on computational fluid dynamics to establish a contribution to train aerodynamics. The numerical simulations are verified against the experimental measurements. It is found that strong unsteady flow develops around the train, particularly at the regions of nose car, leading bogie, articulated bogies, inter-carriage gaps and tail car, due to flow separations and vortex interactions generated around the geometries. High intensity turbulence appears around the nose, bogies, inter-carriage gaps and tail. Strong vortices and high degree of unsteadiness are produced within the flow between the train underbody and the ground, making the flow developed around the bogie regions of high turbulence. Interaction from the inter-car gap leads to a particularly strong vortical flow around the articulated bogie, causing a large slipstream in the regions close to the airspring and a larger drag. Thus the bogie configuration has a noticeable influence on the train underbody flow. [ABSTRACT FROM AUTHOR]

This work aims to study the flow behaviour, phase transformation, and microstructure evolution of aluminium bronze (Cu–9Al–4Fe) alloy. The hot compression behaviour of aluminium bronze were studied using simulator isothermal hot compression tests investigated at strain rates of 0.01–10 s−1 and temperature of 500–800 °C. According to the construction of constitutive equation and three-dimensional hot processing maps, the activation energy was 275.64 kJ/mol. The precipitated fine κⅣ particles during hot compression inhibit grain growth; the coarse κⅡ particles promote dynamic recrystallization through the mechanism of particle-stimulated nucleation (PSN). The formation of deformation twins under the influence of the fine κⅣ particles and high-density annealing twins are formed by stacking fault energy (SFE). Phase transformation by hot compression of the material at 500–800 °C, where the structure consists of the α phase and (α + γ2) eutectoid structure to α + β phase, is important for the increase in the power dissipation factor. Adiabatic shear leads to wedge-shaped cracks at 500 °C and 600 °C, 10 s−1, which pass through the (α + γ2) eutectoid structure and α phase interface with coarse-phase particles. The discontinuous dynamic recrystallization (DDRX) mechanism is the dominant DRX mechanism for aluminium bronze, in which DDRX, characterized by grain boundary bulging, was activated. The strengthening mechanism of aluminium bronze includes dispersion strengthening, twin strengthening, and grain refining strengthening during hot deformation, which leads to the increased activation energy of aluminium bronze alloy.

In the maritime industry, propellers are the most commonly used form of propulsion and are core to the optimum performance of a ship. Generally, the performance characteristics of a marine propeller are determined and analysed by experiments like open water and self-propulsion scale model tests which are costly and time-consuming at the initial design stage. In this study, the computational fluid dynamics (CFD) simulations were performed to evaluate propeller performance. Three Wageningen B-series propellers with varying Expanded Area Ratios (EAR) were modelled with respect to the design constraints, such as ship speed and rotational velocity. The performance of the hydrodynamic coefficients, thrust, torque and open water efficiency are then analysed using the CFD modelling. These characteristics are then validated against experimental data obtained from the Netherlands Ship Model Basin open water test in Wageningen and used to investigate the flow behaviour. The analysis considers the Multiple Reference Frame (MRF) model. This study provided a well-founded framework for applying CFD in the analysis and selection of Wageningen B-series propellers, as well as investigated the relationship between the EAR, flow behaviour, thrust coefficient, and torque coefficient for electric boats. The results show that a lower thrust and torque coefficient can improve the flow behaviour with increasing the efficiency by up to 62%. Furthermore, the outcomes reveal that the lower expanded area ratio of 0.6 is more suitable for electric boats, creating a larger pressure difference of 1.079 MPa and generating extra potential thrust at the same advance ratio, which leads to greater open water efficiency.

Semi-solid extrusion (SSE), an additive manufacturing technique, is gaining significant attention for the printing of thermosensitive drugs. Hydrogels, one of the materials used in SSE, have emerged as a focus in pharmaceutical applications due to their ability to control the release of therapeutic agents spatially and temporally. Understanding the non-Newtonian flow and evaluating the mechanical properties of hydrogel-based materials during extrusion is, however, essential for successful 3D printing. Thus, users often find themselves conducting both rheological and texture profile analyses to characterize the hydrogel. While texturometers are primarily used to evaluate mechanical or sensory properties, viscosity measurements are typically performed using rotational rheometers or viscometers. In this study, we demonstrated how comparable rheological information can be obtained using a texturometer as a capillary rheometer. By preparing similar formulations to a previous study, we compared the rheological data obtained from a rotational rheometer to the data obtained from the texturometer. The means of the parameters obtained by fitting the data from both techniques to the power law model showed insignificant differences. In addition, three clusters were formed based on the flow behaviour and printability of the samples using principal component analysis. Furthermore, the printability was predicted using the samples' consistency and flow indexes, and the regression coefficient was 96.62 and 60.03% for capillary and rotational flow parameters, respectively. This approach thus holds the potential to streamline the time, expertise and equipment required for the rheological characterization of hydrogels for applications in semi-solid extrusion. [Display omitted] [ABSTRACT FROM AUTHOR]

The hot deformation behavior of TB8 titanium alloy with a lamellar α structure in the α+β dulex phase region was investigated. The results show that at the strain rate of 1 s-1, a continuous flow softening phenomenon is observed in the curve of the samples deformed at 650 ℃, while a discontinuous yield phenomenon is visual in the curve of the samples when the deformation temperature is higher than 650 ℃. The discontinuous yield phenomenon is gradually disappeared with increasing deformation temperature and strain rate. When the strain rate is 0.001 s-1 and the deformation temperature is 750 ℃ as well as 800 ℃, typical characteristics of dynamic recrystallization is presented in the curve of the samples. The relationship among peak stress σp temperature T and strain rate ε · and is characterized by Arrhenius-type constitutive equation. The equation between the material constants (α, Q, n and lnA) and strain is constructed. The effect of strain on the material constants (α, Q, n and lnA) of the Arrhenius-type constitutive equation is analyzed. The value of α is increased with true strain, while the values of Q, n and lnA are gradually decreased. The correlation coefficient (R2) and the AARE value between the experimental and the predicted stress are 0.945 and 9.08%, respectively. This indicates that the strain-compensates Arrhenius type constitutive equation can better predict the flow stress value under different deformation conditions for the TB8 titanium alloy with a lamellar α structure deformed in the α+β dulex phase region.

Cavitation in pumps causes unwanted consequences, such as noise, vibrations, and system oscillations. These result in reduced pump efficiency and unstable operation range. Therefore, this study investigates the cavitation behaviours of newly designed centrifugal pumps experimentally and numerically. Computational Fluid Dynamics (CFD) was used to analyse cavitation flow behaviours. The Rayleigh--Plesset expression for bubble dynamics was employed to capture the cavitation phenomenon inside the pump. Numerical simulations were performed and validated by experiments, and good performance characteristics were obtained. The estimated total head drop lines for different cavitation flow rates and performances were analysed numerically. Cavitation was observed near the impeller blade suction for the leading-edge condition in impeller flow passage; moreover, a lower pressure was observed near the impeller blade shroud than the hub in the steady-state condition. [ABSTRACT FROM AUTHOR]

Objective: The main objective of this paper is to analyse and attempt to understand the nature of rheological changes observed and the dynamics of Carbopol NF 980 hydroalcoholic gels neutralized specifically by triethanol amine (TEA), both as a function of time and alcohol type to probe time stabilities and ageing effects in such carbopol gel systems. The rheological changes and dynamics of 3 carbopol gel systems were observed; the gels included a water‐based, ethanol‐based, and isopropyl alcohol‐based gel. It is hoped that this study shall shed light on the dynamical nature and the microstructural evolution of such networked gel systems, which were maintained under closed isothermal conditions and left completely unperturbed. The experimental results can provide the information necessary to understand and proposes plausible mechanisms guiding this dynamical behaviour in hydroalcoholic carbopol gels. Methods: A TA instrument mechanical rheometer was used to measure the viscosity and storage and loss modulus, and a pH meter was utilized to determine the changes in each sample over the period. Results: Studying the differences in the gel structures upon initial preparation illustrated that the ethanol and isopropyl alcohol (IPA) gels differed from the water‐based gel in terms of viscosity, G′, and G″, with the IPA gel displaying the lowest viscosity and moduli values across all shear rates. All the three gel systems exhibited strong shear thinning characteristics and were reminiscent of yield stress type found in colloidal gels. The water‐based gel compared to the hydroalcoholic gels was strongly G′ dominated, with the magnitude of the difference between G′ and G″ observed to be much higher. This reflects that initial formation of the water‐based gel structure possesses a much more rigid structure with a high elastic modulus component dominating. This also suggests that the water‐based gel structure displayed stronger interactions between the carbopol particles when compared to those of the hydroalcoholic gels. Over the 30‐day period, it was observed that the ethanol and water‐based gels did not reveal any appreciable viscosity changes, with only an approximate 12% and 7% change from day 1 to 30, respectively. It was observed that the IPA systems' viscosity drastically increased over the period, with an approximately 77% change from day 1 to 30. The water and ethanol‐based gels also exhibited very similar rheological behaviour over the entire time period with G′ dominating G″. The G″ values of the water and ethanol‐based gels decreased slightly at the end of day 30 by 10% and 16%, respectively, while the G′ values for each sample remained essentially unchanged, increasing only 0.06% for the water‐based gel, and increasing 1.4% for the ethanol‐based gel. This further confirms the relatively stable gel structures attained. For the isopropyl gel system, the storage modulus of the system exhibited an average percent increase of approximately 16% from day 1 to day 30, but interestingly the loss modulus varied the least amongst all the gel systems, with only a 3% increase. The increase in G′ reflects upon the evolution of a more rigid structure by day 30 for the IPA gel. This observation is clearly consistent with the corresponding increase in viscosity observed in the IPA gel. None of the gels tested displayed a consistent pH over the period. The pH of the hydroalcoholic gels was higher than that of the water‐based gel for a majority of the period. The greatest fluctuations in pH were observed for the water and IPA gels, even though the water‐based gel had one of the most stable rheological profiles out of the samples tested. The water, ethanol, and IPA gels' pH increased approximately 25%, 6%, and 5%, respectively, from day 1 to day 30. Conclusion: The rheological and pH study of the 3 hand sanitizer systems over a 30‐day period allowed for rational insights into the plausible reasons responsible for driving the observed rheological changes in these unperturbed systems. For the water‐based gel, we hypothesize that the changes observed are due to physical ageing, where the gel structure has evolved over time to eventually progress towards a more stabilized framework structure. The pH of the gel upon formation was on the lower side. Such a lower pH influences the formation of a gel, which is comparatively less swollen and occupies a slightly lesser volume, and thereby points to a much less compacted gel network structure or alternatively, a more fluid structure. If the particles moved around more, the system was not initially in a state of low energy, causing increased particle movement, and in turn, physical ageing. This could be responsible for the development of a physically altered structure over time. The gel structure dynamically attempts to minimize its free energy by becoming more rigid, which has been observed as being manifested in the decrease of both the viscosity and the G″. For the hydroalcoholic gels, we conjecture that ageing observed was a result of chemical ageing, and the alcohol type employed in the preparation is primarily responsible for exhibiting this effect. The polarities of ethyl alcohol and isopropyl alcohol are key to the stabilization of such resultant network structures which get formed because of neutralization. It has been observed in previous studies that with decreasing polarity, there was an increase in the neutralization needed to obtain the development of a structure half as well developed as the final resultant structure. Isopropyl alcohol is a much less polar solvent compared to ethanol and water, and therefore required higher levels of TEA as the base to neutralize the system. We conjecture that the charged TEA cationic species had a greater propensity to get exchanged with bulk solution in the vicinity of the polymer into the bulk solution, and that the pH fluctuation observed indicated a kinetic exchange process over time, causing the viscosity and moduli profiles to increase along with the pH. At this time though, further investigations need to be carried out to truly understand the underlying instability, and thus dynamics for gel systems of this type. [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a commercial transglutaminase enzyme was dried using an ultrasonic spray freeze drying method and the effects of the process conditions were optimized to maximize the final transglutaminase activity. Accordingly, process parameters affecting enzyme activity were selected, such as nozzle frequency (48 and 120 kHz), flow rate (2, 5 and 8 mL/min) and plate temperature for secondary drying (25, 35 and 45 °C). Moreover, the effects of different pH values (pH=2.0 and 9.0) and high temperature (80 °C) on enzyme activity, physical properties and particle morphology of transglutaminase were discussed. According to the results, transglutaminase preserved its activity despite ultrasonic spray freeze drying. Sonication enhanced the enzyme activity. Using the desirability function method, the optimum process conditions were determined to be flow rate 3.10 mL/min, plate temperature 45 °C and nozzle frequency 120 kHz. The predicted activity ratio was 1.17, and experimentally obtained ratio was 1.14±0.02. Furthermore, enzyme produced by ultrasonic spray freeze drying had low moisture values (2.92-4.36 %) at 8 h of drying. When the morphological structure of the transglutaminase particles produced by ultrasonic spray freeze drying under the optimum conditions was examined, spherical particles with pores on their surfaces were observed. In addition, flow properties of the transglutaminase powders were considered as fair under most conditions according to the Carr index.

Niobium bearing ultralow carbon micro alloyed dual phase steel grade steel with chemical composition of 0.045 wt.% carbon, 0.04 wt.% niobium, 0.59 wt.% chromium, 0.9 wt.% manganese, 0.28 wt.% silicon is investigated. The design of thermomechanical treatment needs knowledge about the flow behaviour at high deformation temperatures, to be used for this steel in industrial plants. Therefore, this work aims to predict, for the investigated steel, the flow behaviour and mean flow stress. A phenomenological constitutive model is established to derive the flow stress using the hyperbolic sinusoidal Arrhenius mathematical model. The relation between stress and strain with Zener‐Hollomon parameter is studied. Mean flow stress has been figured out by measurements taken from compact slab production plant log data using a constitutive model. The constitutive model is further verified by multiple hits of flat compression setup mode at BährTTS820 physical simulator. The tests were performed under specific thermochemical schedule simulating compact slab production plant. The results show good agreement between the calculated flow stress, Non‐recrystallization temperature and experimentally measured values obtained from the physical simulation. Ferrite grain size is modelled and predicted then validated by experimental rolled specimens in a practical hot strip mill. [ABSTRACT FROM AUTHOR]

This paper aims to study the performance of the NASA Rotor 67 transonic fan blade at various operating conditions. First, a steady-state computation along with mesh independence study is done using ANSYS CFX at the design operating speed of the rotor. Then the analysis is carried out at 86%, 92%, 96%, and 105% of the design operating speed. The performance of the rotor is compared and analysed for various off-design operating conditions to evaluate the flow behaviour in transonic speed through the highly twisted fan rotor blade. [ABSTRACT FROM AUTHOR]

The present work describes the effect of Ni/Fe ratio on microstructure, tensile flow and work hardening behaviour of tungsten heavy alloys (WHAs) based on 92 wt. % W with varying Ni/Fe ratios in heat treated and swaged conditions. Evaluation of properties in the heat treated and swaged conditions reflect that the increasing Ni/Fe ratio has resulted in the enhancement of tensile as well as impact properties. Quantitative metallography and fractography have been conducted to identify the role of microstructural attributes on the failure behaviour in both the tensile and impact energy tests. The properties improvements at higher Ni/Fe ratios are due to the realisation of microstructure comprising relatively higher dissolved W in the matrix phase, higher volume fraction of matrix and reduced contiguity of W particles. True stress–true plastic strain curves of present alloys on log–log scale display two- and single-slopes in heat treated and swaged conditions, respectively. The instantaneous work hardening curves reveal the presence of three distinctive regimes (I, II and III) in heat treated and swaged conditions. The second derivatives of true stress–true plastic strain curves are parabola. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sieve plate packing is a newly developed packing that has been used in several industries due to its simple structure and operating flexibility, and no liquid flooding. In this work, first, systematic experiments were conducted to measure the pressure drop of gas flow through six sieve plate packings. The results indicated that the geometric characteristics of the packing have complicated effects on the pressure drops. Based on this, CFD simulations on the gas flow field were conducted using the realizable k‐ε model, and flow behaviours such as the pressure drop, pressure nephogram, and velocity distributions within different packings were obtained. The simulation results clearly showed interesting flow patterns, including the contraction and expansion of the gas stream through the sieve hole, the flow separation on the sharp edge of the hole, and the vortexes formed when gas impacts the downstream plate. By comparing the flow patterns and the pressure drop under different packings operating at different conditions, the effects of the geometric characteristics of the packing on the pressure drop could be clearly distinguished from the flow behaviours, so that the variations in pressure drop with various packing structures were clearly indicated. Finally, based on the experimental data and the simulated results, correlations for the prediction of the pressure drops were proposed. This work will provide a useful basis for understanding the flow behaviour of gas and liquid two‐phase flow in sieve plate packing. [ABSTRACT FROM AUTHOR]

The present work describes a phenomenological approach to explain the instantaneous behaviour of tungsten heavy alloys (WHAs) in heat-treated and swaged conditions. The strengths and elongation values of heat-treated materials are lower and higher than those of the swaged samples respectively. The heat-treated materials exhibit two slopes in true stress–true plastic strain curves and follow the Ludwigson constitutive equation. On the other hand, swaged materials display a single slope and adhere to typical Swift constitutive equation. The latter reflect the presence of pre-strain in the materials due to swaging deformation. The fracture surfaces in heat-treated materials consist of W-W decohesion along with matrix rupture and W-cleavage, while swaged samples consist of mainly W-cleavage. Both the materials display three typical stages (I, II and III) of work hardening. The second derivatives of true stress–true plastic strain curves of these alloys exhibit a perfect parabola although the nature of true stress–true strain as well as true stress–true plastic strain curves is quite different in heat-treated and swaged materials. This has been observed for the first time in WHAs consisting of matrix and W-grains. The shape of the parabola is simple and easy to fit. The fitting parameters of parabolas have been successfully employed to explain the flow behaviour of a large number of tungsten heavy alloys having two-phase microstructure in different processing conditions. [ABSTRACT FROM AUTHOR]

The aerodynamic noise of high-speed trains increases significantly under crosswinds. Researches have typically focused on the characteristics of aerodynamic loads and the corresponding safety issues, with less attention to flow-induced noise characteristics. In the present paper, the near-field unsteady flow behaviour around a pantograph was analysed using a large eddy simulation. The far-field aerodynamic noise from a pantograph was predicted using the Ffowcs Williams-Hawkings acoustic analogy. The results showed that asymmetric characteristics of the flow field could be observed using the turbulent kinetic energy and the instantaneous vortexes in crosswind conditions. Vortex shedding, flow separation and recombination around the pantograph were the key factors for aerodynamic noise generation. The directivity of the noise radiation was inclined towards the leeward side of the pantograph. The aerodynamic noise propagation pattern can be considered as a typical point source on spherical waves when the transverse distance from the pantograph geometrical centre is farther than 8 m. The sound pressure level grew approximately as the 6th power of the pantograph speed. The peak frequency exhibited a linear relationship with the crosswind velocity. The numerical simulation results and wind tunnel experiments had high consistency in the full frequency domain, namely, the peak frequency distribution range, the main frequency amplitude and the spectral distribution shape. [ABSTRACT FROM AUTHOR]

The use of chemically modified starches to improve the physical properties of non-fat stirred yoghurt was investigated. Yoghurts were prepared from non-fat milk powder, sucrose, water and tapioca starch acetates (TSA-1, TSA-2, TSA-3), tapioca distarch phosphates (TDP-1, TDP-2, TDP-3) or native tapioca starch at 1 % (w/w). Syneresis, particle size distribution and viscoelastic properties of the yoghurts were determined, and flow behaviour was described using the Herschel-Bulkley model. Furthermore, interactions between milk proteins and modified starches attributed to protein surface hydrophobicity were characterized. Results showed that yoghurts with starch acetates exhibited higher yield stress, consistency coefficient (K) values, hysteresis loop area, storage modulus (G') and loss modulus (G"). Protein surface hydrophobicity was significantly influenced by the addition of starch acetates, and TSA-3 yoghurt exhibited the lowest values. This study concluded that the addition of TSA-3 starch showed better results in terms of the rheological properties of non-fat yoghurt. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the effect of sucrose replacement by isomalt on rheological, mechanical, and textural properties of aerated coatings made with egg white protein. Novel results, useful to control the manufacture and performance of reduced-sugar meringue-type confectionery coatings, were obtained. Liquid full-sugar samples (powdered sucrose and egg white protein) were prepared by whisking. Liquid reduced-sugar samples were made by replacing 20% and 40% of sucrose by isomalt. Dry discs (3.74 cm diameter) were obtained by heat-treatment (105 °C for 1 h). The analysis of small and large oscillatory shear behaviour (by strain-stress Lissajous plots) and flow curves (by Cross model) of liquid samples were performed. Double uniaxial compression tests were done to obtain mechanical and textural properties of dry discs. The main physical properties and bubble size distributions were also analysed. The partial sucrose replacement by isomalt influenced the behaviour of the studied aerated coatings. • Aerated coatings with partial sucrose replacement by isomalt were studied. • Air bubble size distribution and physical properties were evaluated. • Viscoelasticity and flow were analysed by Lissajous curves and Cross model. • Mechanical and textural properties were found by double uniaxial compression. • Isomalt affected the behaviour of fluid and dry aerated coatings. [ABSTRACT FROM AUTHOR]

The flow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500 thermo-mechanical test simulator with a hydrawedge system in the temperature range of 850–1100 °C and strain rate range of 0.1–50 s−1. The phenomenological constitutive model and the relationship between the Zener–Hollomon (Z) parameter and flow stress were established. The results reveal that the flow softening phenomenon occurs at high strain rate, which is caused by the coupling effect of the adiabatic heating and dynamic recrystallisation (DRX). New grains nucleate preferentially at the original grain boundaries by strain-induced grain boundary migration. With an increase of temperature or strain rate, a part of new grains form in the interior of deformed grains. The DRX grain size and fraction increase with the increase of temperature, however, exhibit a non-linear relationship with strain rate. [ABSTRACT FROM AUTHOR]

In this study, a commercial transglutaminase enzyme was dried using an ultrasonic spray freeze drying method and the effects of the process conditions were optimized to maximize the final transglutaminase activity. Accordingly, process parameters affecting enzyme activity were selected, such as nozzle frequency (48 and 120 kHz), flow rate (2, 5 and 8 mL/min) and plate temperature for secondary drying (25, 35 and 45 °C). Moreover, the effects of different pH values (pH=2.0 and 9.0) and high temperature (80 °C) on enzyme activity, physical properties and particle morphology of transglutaminase were discussed. According to the results, transglutaminase preserved its activity despite ultrasonic spray freeze drying. Sonication enhanced the enzyme activity. Using the desirability function method, the optimum process conditions were determined to be flow rate 3.10 mL/min, plate temperature 45 °C and nozzle frequency 120 kHz. The predicted activity ratio was 1.17, and experimentally obtained ratio was 1.14±0.02. Furthermore, enzyme produced by ultrasonic spray freeze drying had low moisture values (2.92-4.36%) at 8 h of drying. When the morphological structure of the transglutaminase particles produced by ultrasonic spray freeze drying under the optimum conditions was examined, spherical particles with pores on their surfaces were observed. In addition, flow properties of the transglutaminase powders were considered as fair under most conditions according to the Carr index. [ABSTRACT FROM AUTHOR]

A growing interest in development of milk desserts with good nutritional and rheological properties can be observed. A good and stability rheological as well as nutritional properties of such desserts can be provided by applying suitably composed gum mixtures. In this work, the effect of 0.1% κ-carrageenan addition on the rheological properties of based-milk desserts with different oat gum concentrations (0.1, 0.3 and 0.5%) was investigated. All milk desserts tested in presented study showed a time dependent and shear-thinning flow behavior. The mechanical spectra were characterized by storage module (G') greater than loss module (G"), typical for viscoelastic materials such as gels and dispersions. The incorporation of 0.1% κ-carrageenan into milk dessert with different oat gum concentrations allows to obtain stronger gel structure compared to milk dessert with separate oat gum addition. It can be also observed that desserts systems with the 0.1% κ-carrageenan had more stable viscoelastic properties. Moreover, the use the κ-carrageenan addition caused an increase in consistency coefficient (K) and decreased in n-value for Ostwald de Waele rheological model. Combined addition of oat gum and carrageenan allows to obtain milk dessert with stronger texture. The hardness of milk desserts range from 0.32 to 0.49 N for desserts without κ-carrageenan addition and from 0.513 to 0.557 N for desserts with κ-carrageenan. The high synergistic effect of composed gum mixtures on rheological properties of milk dessert occurs at 0.1% oat gum and 0.1% κ-carrageenan concentration. [ABSTRACT FROM AUTHOR]

Steel matrix syntactic foam is a promising lightweight and energy absorbing material. In this study, an infiltration casting technology is developed to prepare syntactic foams, which brings in alumina hollow spheres with an average size of around 3.97 mm to make the pores and enhance the properties of the foams. During the process, melt flow along with heat transfer during the infiltration is investigated. The study shows that melt flow and velocity distribution of molten steel are significantly unstable; the critical solid fraction of the steel is 0.67; and the alumina ceramic mould in which the foams are prepared must be preheated to at least 1000°C to prevent incomplete infiltration. Finally, the microstructure of syntactic foams is studied. [ABSTRACT FROM AUTHOR]

Dika kernels are known for their mucilaginous consistency, but limited work has been reported about it. This study investigated the flowing characteristics (share stress and viscosity) of the dika kernel and its soup; and this was assessed at specific temperatures (30, 50, 70 and 90) °C by the use of a viscometer. All samples behaved as non-Newtonian fluids. The bulk, tapped and loose densities of the powdered samples were obtained to evaluate the Carr index, Hausner ratio and porosity. The viscosity and shear stress of the reconstituted powder and soup samples as a function of the shear rate were investigated (30–90 °C). Dika kernel at its natural moisture content has excellent flowing property (1.118 Hausner ratio, 10.566 Carr index and 20.300% porosity), but increase in moisture content decreased this ability. The viscosity of the soup (165.789–14,546.341 mPa s) was higher than the reconstituted dika (69.831–206.240 mPa s) at all temperature studied. Shear stress was temperature-dependent, and Bingham and Power-law models gave the best predictions of flow. [ABSTRACT FROM AUTHOR]

A novel three products hydrocyclone screen (TPHS) has been successfully developed; it consists of a cylindrical screen embedded in a conventional hydrocyclone (CH). In the new liquid cyclone, the combination of centrifugal classification and screening was employed for particle separation based on size. The aim of this study is to investigate the flow behaviour in TPHS using numerical simulation and experimental validation. A computational fluid dynamics simulation with a 4.35 million grid scheme and linear pressure-strain RSM generated the economic and gridindependence solution, which agreed well with the experiments of particle image velocimetry and water split. The velocity vector profile reveals that TPHS represented similar flow patterns to CH, wherein in addition to the outer downward swirl flow, inner upward swirl flow, central down-flow, second circulatory flow, and mantle, a particular fluid flow named screen underflow was created in TPHS owing to the presence of a cylindrical screen. The velocity distribution demonstrates that in TPHS, relative to CH, with the increase in radius, the lower tangential and higher radial velocity first increased to a peak and subsequently decreased, while the axial velocity primarily reduced to zero, increased in the opposite direction, and finally decreased rapidly to zero again. In addition, a disadvantageous flow, namely, screen backflow, was generated in TPHS, wherein the farther away the flow is from the feed inlet, the earlier this flow behaviour occurred. However, the rational scheme of aperture size and screen length can completely remove the screen backflow in TPHS. [ABSTRACT FROM AUTHOR]

In the present study a phenomenological constitutive model is developed to describe the flow behaviour of 20MnMoNi55 low carbon reactor pressure vessel (RPV) steel at sub-zero temperature under different strain rates. A set of uniaxial tensile tests is done with the variation of strain rates and temperature ranging from 10-4 s-1 to 10-1 s-1 and -80 °C to -140 °C respectively. From the experimental data, family of flow curves at different temperatures and strain rates are generated and fitted exponentially. The strain rate and temperature dependence of the coefficients of the exponential flow curves are extracted from these curves and characterised through a general phenomenological constitutive coupled equation. The coefficients of this coupled equation are optimised using genetic algorithm. Finite element simulation of tensile tests at different strain rates and temperatures are done using this coupled equation in material model of Abaqus FEA software and validated with experimental results. The novelties of proposed model are: (a) it can predict precisely the flow behaviour of tensile tests (b) it is a simple form of equation where fitting parameters are both function of strain rate ratio and temperature ratio, (c) it has ability to characterize flow behaviour with decreasing subzero temperatures and increasing strain rates. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the flow softening and ductile damage of TC6 alloy were investigated using a uniaxial hot tensile test with deformation temperatures of 910 °C∼970 °C and strain rates of 0.01 s−1∼10 s−1. Scanning electron microscopy (SEM) was performed on the deformed specimens to reveal the damage mechanism. The results showed that the flow stress rapidly increases to a peak at a tiny strain, followed by a significant decrease due to flow softening and ductile damage. The ductile damage of the studied TC6 alloy can be ascribe to the nucleation, growth and coalescence of microdefects, and the microvoids preferentially nucleate at the interface of the alpha phase and beta matrix due to the inconsistent strain. Then, a set of unified viscoplastic constitutive equations including flow softening and ductile damage mechanisms was developed and determined, and this set of equations was verified by the experimental flow stress, which indicated the reliability of the prediction. Furthermore, the predicted normalized dislocation density and the adiabatic temperature rise increase with decreasing temperature and increasing strain rate. The predicted damage components show that the microdefects mainly nucleate in the initial stage, but then primarily grow and link together with continuing deformation. Highlights • The flow behaviour and ductile damage mechanism of TC6 alloy were investigated. • A set of physically-based internal-state-variable damage model was developed. • Normalized dislocation density and adiabatic temperature rise were predicted. • The microdefects mainly nucleate in the initial stage. • The microdefects primarily grow and link together with continuing deformation. [ABSTRACT FROM AUTHOR]

Highlights • Gum from Chinese quince seed surface could be quickly solubilized in cold water. • The uronic acid content of CQSG (31.7%) was high. • Rheological properties of Chinese quince seed gum were comprehensively investigated. • The behavior is unique and distinct from other gums in frequency sweep test. Abstract Characterization of the rheological properties of Chinese quince seed gum (CQSG) is fundamental when using it in food production. In the present paper, the chemical compositions and the rheological properties of CQSG at different concentrations, types of salts, temperatures and pH values were characterized by using shear or dynamic rheological experiments. The results demonstrated that uronic acid content of CQSG (31.7%) was high and different concentration CQSG solutions presented Newtonian plateaus followed by shear thinning regions. The viscosities of the gum solutions decreased with the addition of any salt, with increase in temperature and at extreme pH values (3 and 11). The stress and frequency sweep tests demonstrated a unique result in that the crossover frequency shifted to a higher value when the CQSG solution concentration increased. It is the basis for CQSG product development and quality control for its potential applications. [ABSTRACT FROM AUTHOR]

• The seal-vibrissa-shaped cylinder can weaken the regular vortex shedding in its wake. • The seal-vibrissa-shaped cylinder can mitigate the spanwise coherence of wake vortices. • The seal-vibrissa-shaped cylinder can suppresses the fluctuations on cylinder surfaces. • The seal-vibrissa-shaped cylinder can reduce the aerodynamic noise by inhibiting its tonal peak. • The configurations of seal-vibrissa-shaped cylinder can be applied for aerodynamic noise control of cylindrical-like bars. Inspired by the special structure of seal vibrissae and their ability to effectively suppress vortex-induced vibrations, this paper studies the characteristics of flow and aerodynamic noise generated around a seal-vibrissa-shaped cylinder at a Reynolds number (based on the hydrodynamic diameter and freestream velocity) of 6 × 104 using the delayed detached-eddy simulation model combined with the acoustic analogy approach. The far-field aerodynamic noise has also been measured at Reynolds numbers of 6 × 104∼1.2 × 105 in an anechoic wind tunnel to compare the seal-vibrissa-shaped cylinder with cylindrical and elliptical bars of the same characteristic dimensions. The calculated spectra of aerodynamic noise agree well with the wind tunnel measurements, verifying the accuracy of the numerical simulations. It is found that the three-dimensional flow separations introduced by the alternative saddle and nodal planes of the seal-vibrissa-shaped cylinder inhibit shear layer interactions and reduce the spanwise coherence, resulting in a wake with no dominant coherent structures and thus suppressing pressure fluctuations on the solid surfaces. The configuration of seal-vibrissa-shaped cylinder eliminates the regular Kármán vortex street which generally occurs in a cylinder wake, and consequently inhibits the tonal peak in the aerodynamic noise. The sound pressure level is also reduced in most frequencies. The consistency of the normalized spectra of the far-field aerodynamic noise and the vortex shedding frequency at different inflow speeds demonstrates the high accuracy of the anechoic wind tunnel measurements. Compared with cylinders with circular or elliptical cross sections, the seal-vibrissa-shaped cylinder effectively reduces the flow-induced noise by, respectively, 13 dB or 11 dB for a far-field receiver of 90° at Reynolds number of 6 × 104, showing great potential in reducing aerodynamic noise. [ABSTRACT FROM AUTHOR]

Background: One of the most serious adverse events potentially occurring during vertebroplasty is cement leakage. Associated risks for the patient could be reduced if cement filling is preoperatively planned. This requires a better understanding of cement flow behaviour. Therefore, the aim of the present study was to investigate bone cement distribution in artificial inhomogeneous cancellous bone structures during a simulated stepwise injection procedure. Methods: Four differently coloured 1-mL cement portions were injected stepwise into six open-porous aluminum foam models with simulated leakage paths. Each model was subsequently cross-sectioned and high-resolution pictures were taken, followed by anatomical site allocation based on the assumption about a posterior insertion of the cannula. A radial grid consisting of 36 equidistant beams (0°–350°) was applied to evaluate the cement flow along each beam by measuring the radial length of each cement portion (total length) and of all four portions together (distance to border). Independently from the injection measurements, the viscosity of 20 cement portions was measured at time points corresponding to the start of the first and the end of the last injection. Results: Despite some diffuse colour transitions at the borderlines, no interfusion between the differently coloured cement portions was observed. The two highest values for total length of each of the first three injected cement portions and for distance to border were indicated in directions anterior bilateral to the cannula along the 120°, 240° and 250° beams and posterolateral along the 60° beam. The two highest total lengths for the fourth cement portion were registered in the direction of the cannula along the 170° and 180° beams. Standard deviations of total length for each of the last three injected portions and for distance to border were with two highest values in directions anterior bilateral to the cannula along the 120°, 150°, 240° and 250° beams and opposite to the direction of the cannula along the 10° beam. The two highest values for the first cement portion were registered posterior bilateral to the cannula along the 70° and 350° beams. The values for averaged standard deviations of the total length of the fourth cement portion and the distance to border were significantly higher in comparison to the first cement portion (p ≤ 0.020). Dynamic viscosity at the start of the first injection was 343 ± 108 Pa∙s and increased to 659 ± 208 Pa∙s at the end of the fourth injection. Conclusion: The simulated leakage path seemed to be the most important adverse injection factor influencing the uniformity of cement distribution. Another adverse factor causing dispersion of this distribution was represented by the simulated bone marrow. However, the rather uniform distribution of the totally injected cement amount, considered as one unit, could be ascribed to the medium viscosity of the used cement. Finally, with its short waiting time of 45 s, the stepwise injection procedure was shown to be ineffective in preventing cement leakage.

Abstract The effect of adding NaCl or CaCl 2 on particle size distribution and flow behaviour of caseinomacropeptide (CMP) aqueous solutions was investigated over a wide range of concentrations (0–200 mmol L−1), temperatures (5–60 °C) and during 14 days of storage. In the absence of salts, CMP mainly presented a monomeric form at pH 7.0. If sodium or calcium chloride is added, hydrophobic associations of CMP is promoted due to screening of electric charges. Calcium chloride had a bigger impact than NaCl. Indeed, small variations in CaCl 2 concentration induced major changes in size distributions and increased the viscosity and the cloudiness of CMP solutions upon storage. The largest aggregates and highest viscosities were obtained at concentrated regime (CMP concentration > 8 g/100 g), high CaCl 2 concentration (>1.2 mmol g−1 CMP) and upon storage. Highlights • Sodium and calcium chloride caused attractive interactions between CMP monomers at pH 7.0. • CMP self-assembly had a cation specific effect; calcium ions had a biggest influence. • CMP solutions allowed the incorporation of large amounts of CaCl 2. • Viscosity of CMP-salt solutions decreased with increasing temperature. • Viscosity of CMP-CaCl 2 solutions can be enhanced by storage. [ABSTRACT FROM AUTHOR]

Acoustic streaming phenomena of ultrasound propagation through liquid media was investigated experimentally employing particle image velocimetry (PIV). Parameters associated with the ultrasonic processor of ultrasonic amplitude ( i.e. , acoustic power) and transducer tip diameter ( i.e. , surface area), as well as, fluid rheology ( i.e. , water, glycerol solution and CMC solution), were studied for their effects on overall flow behaviour and fluid velocity. PIV yielded velocity gradient maps, demonstrating the acoustic streaming phenomena of ultrasound and its associated flow behaviour as a function of ultrasonic amplitude and fluid rheology, whereby increasing amplitude allowed for greater penetration of the acoustic-beam through the bulk of the fluid, and increasing fluid rheology yielded the converse effect. Moreover, upon impingement of the acoustic-beam with the base of vessel, vortex formation occurred, yielding a recirculation pattern. The maximum observed fluid velocities for water, glycerol solution and CMC solution were 0.329 m s −1 , 0.423 m s −1 , and 0.304 m s −1 , respectively (large diameter sonotrode tip for an ultrasonic amplitude of 80%). Furthermore, shear rates were attained (maximum values of 24.25 s −1 ), and Reynolds numbers were determined in order to assess the degree of turbulence as a function of investigated parameters. [ABSTRACT FROM AUTHOR]