Flow characteristics within the wall boundary layers of swirling steam flow in a pipe comprising horizontal and inclined sections

Afrasyab Khan,Mohd Sobri Takriff,Masli Irwan Rosli,Nur Tantiyani Ali Othman,Khairuddin Sanaullah,Andrew Ragai Henry Rigit,Ajmal Shah,Atta Ullah 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.1

Handling and utilization of steam flow efficiently to obtain various tangible industrial outcomes relies mainly upon how to optimize various flow parameters like boundary layer thickness, skewness, shear stress, and turbulent dissipation for minimum losses such as pressure and heat. Swirling steam flow, driven by a propeller through a circular duct along horizontal and inclined surfaces presents an interesting flow regime that includes the boundary layer flows close to the wall of the pipe and weak and uniform flow that prevails across the inner region of the pipe. Such flow was investigated here with a specially designed experimental facility. Convective Instabilities were observed that propagate along the axial direction in a nonlinear fashion. It was observed that the operating conditions could be optimized for measuring the shear stresses based on the intersection of the profiles under the effect of variations in the inlet pressure of steam and the rotational speed of the propeller. We found that the flow transformed from positive to negative skewness when the rotational speed of the propeller was raised from 4-14 thousand per minute at 10 bars of constant inlet steam pressure. More area came under the effect of reduced skin friction when the rotational speed of the propeller was raised. More turbulent energy was found to be dissipated when the rotational speed of the propeller was raised. It was found that yet the dissipation of the turbulent energy takes place under the joint effect of inlet pressure of steam and the rotational speed of the propeller, but the exact effect of any one of these two operating parameters still needs to be determined and requires further investigation.

Investigation of expanding-folding absorbers with functionally graded thickness under axial loading and optimization of crushing parameters

Chunwei Zhang,Limeng Zhu,Farayi Musharavati,Afrasyab Khan,Tamer A. Sebaey 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.6

In this study, a new type of energy absorbers with a functionally graded thickness is investigated, these type of absorbers absorb energy through expanding-folding processes. The expanding-folding absorbers are composed of two sections: a thin-walled aluminum matrix and a thin-walled steel mandrel. Previous studies have shown higher efficiency of the mentioned absorbers compared to the conventional ones. In this study, the effect of thickness which has been functionally-graded on the aluminum matrix (in which expansion occurs) was investigated. To this end, initial functions were considered for the matrix thickness, which was ascending/descending along the axis. The study was done experimentally and numerically. Comparing the experimental data with the numerical results showed high consistency between the numerical and experimental results. In the final section of this study, the best energy absorber functionally graded thickness was introduced by optimization using a thirdorder genetic algorithm. The optimization results showed that by choosing a minimum thickness of 1.6 mm and the exponential coefficient of 3.25, the most optimal condition can be obtained for descending thickness absorbers.

Elastic wave phenomenon of nanobeams including thickness stretching effect

Eyvazian, Arameh,Zhang, Chunwei,Musharavati, Farayi,Khan, Afrasyab,Mohamed, Abdeliazim Mustafa Techno-Press 2021 Advances in nano research Vol.10 No.3

The present work deals with an investigation on longitudinal wave propagation in nanobeams made of graphene sheets, for the first time. The nanobeam is modelled via a higher-order shear deformation theory accounts for both higher-order and thickness stretching terms. The general nonlocal strain gradient theory including nonlocality and strain gradient characteristics of size-dependency in order is used to examine the small-scale effects. This model has three-small scale coefficients in which two of them are for nonlocality and one of them applied for gradient effects. Hamilton supposition is applied to obtain the governing motion equation which is solved using a harmonic solution procedure. It is indicated that the longitudinal wave characteristics of the nanobeams are significantly influenced by the nonlocal parameters and strain gradient parameter. It is shown that higher nonlocal parameter is more efficient than lower nonlocal parameter to change longitudinal phase velocities, while the strain gradient parameter is the determining factor for their efficiency on the results.

Wave propagation analysis of porous functionally graded curved beams in the thermal environment

Xinli Xu,Chunwei Zhang,Farayi Musharavati,Tamer A. Sebaey,Afrasyab Khan 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.6

In the present paper, wave propagation behavior of porous temperature-dependent functionally graded curved beams within the thermal environment is analyzed for the first time. A recently-developed method is utilized which considers the reciprocal effect of mass density and Young’s modulus in order to explore the influence of porosity. Three different types of temperature variation (uniform temperature change (UTC), linear temperature change (LTC), sinusoidal temperature change (STC)) are employed to study the effect of various thermal loads. Euler-Bernoulli beam theory, also known as classic beam theory is implemented in order to derive kinetic and kinematic relations, and then Hamilton’s principle is used to obtain governing equations of porous functionally graded curved beams. The obtained governing equations are analytically solved. Eventually, the influences of various parameters such as wave number, porosity coefficient, various types of temperature change and power index are covered and indicated in a set of illustrations.

Investigation of performance of steel plate shear walls with partial plate-column connection (SPSW-PC)

Mojtaba Gorji Azandariani,Majid Gholhaki,Mohammad Ali Kafi,Tadeh Zirakian,Afrasyab Khan,Hamid Abdolmaleki,Hamid Shojaeifar 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.1

This research endeavor intends to use the implicit finite element method to investigate the structural response of steel shear walls with partial plate-column connection. To this end, comprehensive verification studies are initially performed by comparing the numerical predictions with several reported experimental results in order to demonstrate the reliability and accuracy of the implicit analysis method. Comparison is made between the hysteresis curves, failure modes, and base shear capacities predicted numerically using ABAQUS software and obtained/observed experimentally. Following the validation of the finite element analysis approach, the effects of partial plate-column connection on the strength and stiffness performances of steel shear wall systems with different web-plate slenderness and aspect ratios under monotonic loading are investigated through a parametric study. While removal of the connection between the web-plate and columns can be beneficial by decreasing the overall system demand on the vertical boundary members, based on the results and findings of this study such detachment can lower the stiffness and strength capacities of steel shear walls by about 25%, on average.

Thermal postbuckling of shear deformable multiscale hybrid composite beams

Arameh Eyvazian,Chunwei Zhang,Mohammad Alkhedher,Murat Demiral,Afrasyab Khan,Tamer A. Sebaey 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.4

This research is deal with thermal buckling and post-buckling of carbon nanotube/fiber/polymer composite beams. The beam is considered to be under uniform temperature rise. Firstly, the effective material properties of a two phase nanocomposite consisting of CNT and polymer are extracted. Then, the modified Chamis rule is utilized to obtain the equivalent thermo-mechanical properties of multiscale hybrid composite (MHC). Based on the first order shear deformation theory, Von-Karman type of geometrically nonlinear strain-deformation equations and also the virtual work rule, the equilibrium equations of a three phace composite beam are derived. Bifurcation buckling and also the thermal post-buckling is analysed using the generalized differential quadrature technique. In the thermal buckling phenomena, a linear eigenvalue problem is solved; however, due to the nonlinearity, the thermal postbuckling study is performed using an iterative displacement control strategy. After validation study, several novel results demonstrate the influences of length-to-thickness ratio, agglomeration of applied CNTs and fibers in the composite media and number and orientation of layers on the critical temperature and displacement loading path.

Dispersion of waves characteristics of laminated composite nanoplate

Xinli Xu,Chunwei Zhang,Farayi Musharavati,Tamer A. Sebaey,Afrasyab Khan 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3

The current work fills a gap of a small-scale study on wave propagation behavior of symmetric, antisymmetric, and quasi-isotropic cross/angle-plies laminated composite nanoplates. The governing equations are derived through the Hamiltonian principle for four-variable refined shear deformation plate theory in conjunction with the assumption of a non-classical theory, and then size-dependent formulations are solved via an analytical solution procedure. This work provides information to accurately analyze the influence of lay-up numbers and sequences, geometry, fiber orientations, and wave numbers on the size-dependent wave propagation response of laminated composite nanoplates.