Search results

1 – 10 of 719
Article
Publication date: 3 January 2023

Pravin Hindurao Yadav, Sandeep R. Desai and Dillip Kumar Mohanty

The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a…

Abstract

Purpose

The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a parallel triangular finned tube array subjected to water cross flow.

Design/methodology/approach

The experiment was conducted on finned tube arrays with a fin height of 6 mm and fin density of 3 fins per inch (fpi) and 9 fpi. A dedicated setup has been developed to examine fluid elastic instability and vortex shedding. Nine parallel triangular tube arrays with a pitch to tube diameter ratio of 1.78 were considered. The plain tube arrays, coarse finned tube arrays and fine finned tube arrays each of steel, copper and aluminium materials were tested. Plain tube arrays were tested to compare the results of the finned tube arrays having an effective tube diameter same as that of the plain tube.

Findings

A significant effect of fin density and tube material with a variable mass damping parameter was observed on the instability threshold. In the parallel triangular finned tube array subjected to water cross flow, a delay in the instability threshold was observed with an increase in fin density. For steel and aluminium tube arrays, the natural frequency is 9.77 Hz and 10.38 Hz, which is close to each other, whereas natural frequency of the copper tubes is 7.40 Hz. The Connors’ stability constant K for steel and aluminium tube arrays is 4.78 and 4.87, respectively, whereas it is 5.76 for copper tube arrays, which increases considerably compared to aluminum and steel tube arrays. The existence of vortex shedding is confirmed by comparing experimental results with Owen’s hypothesis and the Strouhal number and Reynolds number relationship.

Originality/value

This paper’s results contribute to understand the effect of tube materials and fin density on fluid elastic instability threshold of finned tube arrays subjected to water cross flow.

Details

World Journal of Engineering, vol. 21 no. 2
Type: Research Article
ISSN: 1708-5284

Keywords

Open Access
Article
Publication date: 19 March 2024

Feng Chen, Zhongjin Wang, Dong Zhang and Shuai Zeng

Explore the development trend of chemically-improved soil in railway engineering.

Abstract

Purpose

Explore the development trend of chemically-improved soil in railway engineering.

Design/methodology/approach

In this paper, the technical standards home and abroad were analyzed. Laboratory test, field test and monitoring were carried out.

Findings

The performance design system of the chemically-improved soil should be established.

Originality/value

On the basis of the performance design, the test methods and standards for various properties of chemically-improved soil should be established to evaluate the improvement effect and control the engineering quality.

Details

Railway Sciences, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 6 March 2024

Ahmed EL Hana, Ahmed Hader, Jaouad Ait Lahcen, Salma Moushi, Yassine Hariti, Iliass Tarras, Rachid Et Touizi and Yahia Boughaleb

The purpose of the paper is to conduct a numerical and experimental investigation into the properties of nanofluids containing spherical nanoparticles of random sizes flowing…

Abstract

Purpose

The purpose of the paper is to conduct a numerical and experimental investigation into the properties of nanofluids containing spherical nanoparticles of random sizes flowing through a porous medium. The study aims to understand how the thermophysical properties of the nanofluid are affected by factors such as nanoparticle volume fraction, permeability of the porous medium, and pore size. The paper provides insights into the behavior of nanofluids in complex environments and explores the impact of varying conditions on key properties such as thermal conductivity, density, viscosity, and specific heat. Ultimately, the research contributes to the broader understanding of nanofluid dynamics and has potential implications for engineering and industrial applications in porous media.

Design/methodology/approach

This paper investigates nanofluids with spherical nanoparticles in a porous medium, exploring thermal conductivity, density, specific heat, and dynamic viscosity. Studying three compositions, the analysis employs the classical Maxwell model and Koo and Kleinstreuer’s approach for thermal conductivity, considering particle shape and temperature effects. Density and specific heat are defined based on mass and volume ratios. Dynamic viscosity models, including Brinkman’s and Gherasim et al.'s, are discussed. Numerical simulations, implemented in Python using the Langevin model, yield results processed in Origin Pro. This research enhances understanding of nanofluid behavior, contributing valuable insights to porous media applications.

Findings

This study involves a numerical examination of nanofluid properties, featuring spherical nanoparticles of varying sizes suspended in a base fluid with known density, flowing through a porous medium. Experimental findings reveal a notable increase in thermal conductivity, density, and viscosity as the volume fraction of particles rises. Conversely, specific heat experiences a decrease with higher particle volume concentration.xD; xA; The influence of permeability and pore size on particle volume fraction variation is a key focus. Interestingly, while the permeability of the medium has a significant effect, it is observed that it increases with permeability. This underscores the role of the medium’s nature in altering the thermophysical properties of nanofluids.

Originality/value

This paper presents a novel numerical study on nanofluids with randomly sized spherical nanoparticles flowing in a porous medium. It explores the impact of porous medium properties on nanofluid thermophysical characteristics, emphasizing the significance of permeability and pore size. The inclusion of random nanoparticle sizes adds practical relevance. Contrasting trends are observed, where thermal conductivity, density, and viscosity increase with particle volume fraction, while specific heat decreases. These findings offer valuable insights for engineering applications, providing a deeper understanding of nanofluid behavior in porous environments and guiding the design of efficient systems in various industrial contexts.

Details

Multidiscipline Modeling in Materials and Structures, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 6 October 2023

Cleiton Lazaro Fazolo De Assis and Cleber Augusto Rampazo

This paper aims to evaluate the mechanical behaviour of polycarbonate/acrylonitrile butadiene styrene (PC/ABS) filaments for fusion filament fabrication (FFF). PC/ABS have emerged…

Abstract

Purpose

This paper aims to evaluate the mechanical behaviour of polycarbonate/acrylonitrile butadiene styrene (PC/ABS) filaments for fusion filament fabrication (FFF). PC/ABS have emerged as a promising material for FFF due to their excellent mechanical properties. However, the optimal processing conditions and the effect of the blending ratio on the mechanical properties of the resulting workpieces are still unclear.

Design/methodology/approach

A statistical factorial matrix was designed, including infill pattern, printing speed, nozzle size, layer height and printing temperature as factors (with three levels). A total of 810 workpieces were printed using PC/ABS blends filament with the FFF. The workpieces’ finishing and mass were evaluated. Tensile tests were performed. Analysis of variance was performed to determine the main effects of the processing conditions on the mechanical properties.

Findings

The results showed that the PC/ABS (70/30) exhibited higher tensile. Tensile rupture corresponded to 30% of the tensile strength. The infill pattern showed the highest contribution to the responses. The concentric pattern showed higher tensile strength. Tensile strength and mass ratio demonstrated the influence of mass on tensile strength. The influence of printing parameters on deformation depended on the blend proportions. Higher printing speed and lower layer height provided better quality workpieces.

Originality/value

This study has implications for the design and manufacturing of three-dimensional printed parts using PC/ABS filaments. An extensive experimental matrix was applied, aiming at a complete understanding of mechanical behavior, considering the main printing parameters and combinations not explored by literature.

Details

Rapid Prototyping Journal, vol. 30 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 20 October 2023

Ajay Kumar Jaiswal and Pallab Sinha Mahapatra

Maintaining the turbine blade’s temperature within the safety limit is challenging in high-pressure turbines. This paper aims to numerically present the conjugate heat transfer…

Abstract

Purpose

Maintaining the turbine blade’s temperature within the safety limit is challenging in high-pressure turbines. This paper aims to numerically present the conjugate heat transfer analysis of a novel approach to mini-channel embedded film-cooled flat plate.

Design/methodology/approach

Numerical simulations were performed at a steady state using SST kω turbulence model. Impingement and film cooling are classical approaches generally adopted for turbine blade analysis. The existing film cooling techniques were compared with the proposed design, where a mini-channel was constructed inside the solid plate. The impact of the blowing ratio (M), Biot number (Bi) and temperature ratio (TR) on overall cooling performance was also studied.

Findings

Overall cooling effectiveness was always shown to be higher for mini-channel embedded film-cooled plates. The effectiveness increases with increasing the blowing ratio from M = 0.3 to 0.7, then decreases with increasing blowing ratio (M = 1 and 1.4) due to lift-off conditions. The mini-channel embedded plate resulted in an approximately 21% increase in area-weighted average overall effectiveness at a blowing ratio of 0.7 and Bi = 1.605. The lower uniform temperature was also found for all blowing ratios at a low Biot number, where conduction heat transfer significantly impacts total cooling effectiveness.

Originality/value

To the best of the authors’ knowledge, this study presents a novel approach to improve the cooling performances of a film-cooled flat plate with better cooling uniformity by using embedded mini-channels. Despite the widespread application of microchannels and mini-channels in thermal and fluid flow analysis, the application of mini-channels for blade cooling is not explored in detail.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 29 December 2023

Sanyam Sharma and Rajiv Verma

This study aims to investigate the stability performance of partial journal bearings of 120° and 180° partial angles with micropolar lubricant.

Abstract

Purpose

This study aims to investigate the stability performance of partial journal bearings of 120° and 180° partial angles with micropolar lubricant.

Design/methodology/approach

To investigate the stability characteristics of partial journal bearing, a MATLAB source code is written. To solve the Reynolds’ equation, the finite element method is used. Stability performances of 120° and 180° partial journal bearings are computed for a wide range of non-dimensional micropolar fluid parameters and working eccentricities.

Findings

The presented results provide design data for stability parameters in terms of equivalent stiffness, whirl frequency ratio, critical mass and threshold speed of the rotor with respect to eccentricities and material size of the lubricant. The stability of 180° partial journal bearing is found to be higher than 120° partial journal bearing.

Originality/value

In open literature, it is rare to find the stability of a partial journal bearing lubricated with micropolar fluid. Very few researchers have studied the combined effect of eccentricities and micropolar lubricant parameters on the dynamic performance of such bearings. Hence, it is important to study the dynamic stability to explore the complete investigation of the performance of partial journal bearings with micropolar fluid.

Details

Industrial Lubrication and Tribology, vol. 76 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 7 November 2023

Kashif Irshad, Amjad Ali Pasha, Mohammed K. Al Mesfer, Mohd Danish, Manoj Kumar Nayak, Ali Chamkha and Ahmed M. Galal

The entropy and thermal behavior analyses of non-Newtonian nanofluid double-diffusive natural convection inside complex domains may captivate a bunch of scholars’ attention…

Abstract

Purpose

The entropy and thermal behavior analyses of non-Newtonian nanofluid double-diffusive natural convection inside complex domains may captivate a bunch of scholars’ attention because of the potential utilizations that they possess in modern industries, for example, heat exchangers, solar energy collectors and cooling of electronic apparatuses. This study aims to investigate the second law and thermal behavior of non-Newtonian double-diffusive natural convection (DDNC) of Al2O3-H2O nanofluid within a C-shaped cavity emplacing two hot baffles and impacted by a magnetic field.

Design/methodology/approach

For the governing equations of the complicated and practical system with all considered parameters to be solved via a formidable numerical approach, the finite element method acts as an approach to achieving the desired solution. This method allows us to gain a detailed solution to the studied geometry.

Findings

This investigation has been executed for the considered parameters of range, such as power-law index, baffle length, Lewis number, buoyancy ratio, Hartmann number and Rayleigh number. The main results reveal that isothermal and concentration lines are significantly more distorted, indicating intensified concentration and temperature distributions because of the growth of baffle length (L). Nuave decreases by 8.4% and 0.8% while it enhances by 49.86% and 33.87%, respectively, because of growth in the L from 0.1 to 0.2 and 0.2 to 0.3.

Originality/value

Such a comprehensive study on the second law and thermal behavior of DDNC of Al2O3-H2O nanofluid within a C-shaped cavity emplacing two hot baffles and impacted by magnetic field has not yet been carried out.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 19 August 2022

Yuting Lu, Wanwan Fu, hao Ren, Shifang Wu, Jiesheng Liu and Hao Peng

The purpose of this paper is to develop a high-performance composite emulsion cement waterproof coating. The coating has excellent durability and is effective in protecting cement…

Abstract

Purpose

The purpose of this paper is to develop a high-performance composite emulsion cement waterproof coating. The coating has excellent durability and is effective in protecting cement mortar substrates from harmful ions.

Design/methodology/approach

The polymer cement waterproof coatings with different emulsion compounding ratios were tested for mechanical properties and water resistance after alkali immersion, water immersion, thermal aging and UV aging, and the coatings were analyzed by infrared spectroscopy after aging to evaluate its durability. Meanwhile, the coating that presents favorable durability was applied to cement mortar test blocks. The protective effect of the coating on the test blocks was tested by immersion method, and X-ray diffraction analysis was performed on the eroded test blocks.

Findings

The coating with neoprene latex/acrylate latex weight ratio of 90/10 presents favorable durability and has superior overall performance. Besides, when it is applied to cement mortar blocks, the coatings effectively reduced the erosive effect of harmful ions on cement mortar blocks, resulting in much lower mass change ratios and less internal structural damage of the blocks significantly.

Originality/value

The obtained coating will be of great application potential for use in building waterproofing construction. Moreover, the coating can practically prevent chloride ions and sulfate ions from penetrating cement-based materials.

Details

Pigment & Resin Technology, vol. 53 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 22 January 2024

Peng Yin, Tao Liu, Baofeng Pan and Ningbo Liu

The coal-based synthetic natural gas slag (CSNGS) is a solid waste remaining from the incomplete combustion of raw coal to produce gas. With the continuous promotion of efficient…

Abstract

Purpose

The coal-based synthetic natural gas slag (CSNGS) is a solid waste remaining from the incomplete combustion of raw coal to produce gas. With the continuous promotion of efficient and clean utilization of coal in recent years, the stockpiling of CSNGS would increase gradually, and it would have significant social and environmental benefits with reasonable utilization of CSNGS. This study prepared a new geopolymer by mixing CSNGS with PC42.5 cement in a certain mass ratio as the precursor, with sodium hydroxide and sodium silicate solution as the alkali activators.

Design/methodology/approach

The formulation of coal-based synthetic natural gas slag geopolymer (CSNGSG) was determined by an orthogonal test, and then the strength mechanism and microstructure of CSNGSG were characterized by multi-scale tests.

Findings

The results show that the optimum ratio of CSNGSG was a sodium silicate modulus of 1.3, an alkali dosage of 21% and a water cement ratio of 0.36 and the maximum unconfined compressive strength of CSNGSG at 7 d was 26.88 MPa. The increase of curing temperature could significantly improve the compressive strength of CSNGSG, and the curing humidity had little effect on the compressive strength of CSNGSG. The development of the internal strength of CSNSG at high temperatures consumed SiO2, Al2O3 and CaO and the intensity of corresponding crystalline peaks decreased.

Originality/value

Moreover, the vibration of chemical bonds in different wavenumbers also revealed the reaction mechanism of CSNSG from another perspective. Finally, the relevant test results indicated that CSNGS had practical application value as a raw material for the preparation of geopolymer cementing materials.

Details

Multidiscipline Modeling in Materials and Structures, vol. 20 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 15 August 2022

Wanting Zhao and Lijun Chen

Self-crosslinked long fluorocarbon acrylate polymer latex has good hydrophobic and oleophobicity, weather resistance, aging resistance, stability and other excellent properties…

Abstract

Purpose

Self-crosslinked long fluorocarbon acrylate polymer latex has good hydrophobic and oleophobicity, weather resistance, aging resistance, stability and other excellent properties, which make the polymer be widely used in coatings, dyes, adhesives and other products. The purpose of this study is to prepare self-crosslinked long fluorocarbon acrylate polymer latex via semi-continuous seeded emulsion technology and carry out comparative study on two different cross-linked monomers.

Design/methodology/approach

Methyl methacrylate (MMA) and butyl acrylate (BA) were used as the main monomers, dodecafluoroheptyl methacrylate (DFMA) as the fluoromonomer, hydroxypropyl methacrylate (HPMA) and N-methylol acrylamide (NMA) as cross-linked monomers, and 1-allyloxy-3–(4-nonylphenol)-2-propanol polyoxyethylene (10) ether (ANPEO10) and 1-allyloxy-3–(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate (DNS-86) as compound emulsifiers via the semicontinuous-seeded emulsion polymerization.

Findings

The properties of the polymer emulsions, which are prepared with two different cross-linked monomers, are compared and discussed, and it is concluded that HPMA is more suitable for the preparation of self-crosslinked polymer emulsions. The formula of the polymer latex is ANPEO10: DNS-86 = 1:1, and the mass ratio of the monomers used in the polymer is MMA: BA: DFMA: HPMA = 14.40:14.40:0.60:0.60.

Practical implications

Self-crosslinked long fluorocarbon acrylate polymer latex can be used in many fields such as coatings, dyes, adhesives and other products.

Originality/value

The self-crosslinked long fluorocarbon acrylate polymer latex is prepared by mixing the nonionic emulsifier ANPEO10 and the anionic emulsifier DNS-86 when potassium persulfate is used as the thermal decomposition initiator and the semicontinuous-seeded emulsion technology is adopted and the comparative study on two different cross-linked monomer is carried out, which is not reported in the open literatures.

1 – 10 of 719