As power demand has enlarged, the exploration of green energy sources has also expanded. In recent ages, hydrokinetic energy technology has become the primary research domain of green energy generation. In various types of hydrokinetic turbines (HKTs) systems, cross flow HKTs (CFHKTs) have become indispensable equipment in riverine water sources compared to axial flow HKTs. CFHKTs are easy to install under low head and low fluid discharge conditions. However, it is inefficient compared to large-scale conventional hydro turbines. Therefore, to upgrade the efficiency of CFHKTs, various numerical and experimental research studies have been executed on CFHKTs configurations. In this review study, a detailed review of the CFHKTs rotor configurations is being discussed, in addition to their site-specific suitability, methods to improve their performance, and design optimization. The suitability of optimization techniques on the CFHKTs is also being discussed in detail. According to most of the previous research studies, it can be concluded that the combined CFHKTs indicates better performance and self-starting characteristics compared to the individual lift and drag based HKTs as it possesses the merits of both the Darrieus and the Savonius rotors. The performance of this hybrid CFHKTs rotor can be further improved by using flow augmentation techniques and by optimizing or modifying its design parameters. The analysis of this review study also highlights the details of the challenges and recommendations of all three CFHKTs types. Rotor cavitation, rotational direction, and fatigue effects on the performance of the CFHKTs will be focused as a future scope of this study.
In this work, a modified super-twisting algorithm (MSTA) is developed as an effective way to address the main shortcomings of field-oriented control (FOC) in induction machine (IM) drives. The MSTA method provides a simpler design, lowers computational demands, and is easier to implement. It also offers greater robustness, positioning it as a practical alternative to conventional proportional-integral (PI)-based FOC systems. The proposed FOC-MSTA drive was implemented and tested in MATLAB using a 1.5 kW IM across a range of operating conditions, including constant and varying load torques, changes in stator resistance, and shifts in the rotation direction. The FOC-MSTA approach yielded notable performance gains compared to the conventional FOC-PI method. In five distinct test scenarios, it consistently reduced torque ripple by 23.5
Compact heat exchangers with triply periodic minimal surface (TPMS) cores have emerged as a promising option for advanced thermal management; however, they typically exhibit high pressure drops, making it necessary to evaluate design aspects such as inlet nozzles to mitigate this penalty. This study addresses the gap regarding inlet-nozzle design for pressure-drop reduction by investigating whether and to what extent the inlet-nozzle geometry can reduce the pressure drop in TPMS cores at different porosity levels. To this end, three different nozzle geometries were proposed and evaluated across multiple porosity levels: a divergent nozzle, a conical nozzle, and a divergent–convergent nozzle that penetrates the core. Pressure drop was experimentally measured in additively manufactured polymer gyroid cores with porosities ranging from 0.33 to 0.42 for each nozzle geometry. Simulations were validated against experimental data for a porosity of 0.39, with a maximum deviation of 4.4
Nonlinear equilibrium-path transitions of functionally graded (FG) circular shallow arches with elastic rotational end restraints under full-span uniformly distributed vertical dead loading are investigated. Starting from finite-deformation fiber kinematics and finite-strain measures, three small-material-strain Euler–Bernoulli models are derived: an exact-rotation (ER) model retaining exact centerline geometry and curvature, a metric-consistent von Kármán (VK) model, and a shallow von Kármán (SVK) model. A nine-field mixed field formulation is discretized by the generalized differential quadrature method and solved using bordered cylindrical arc-length continuation. Model fidelity is assessed against two-dimensional finite-deformation, finite-strain ABAQUS simulations for 50 cases using load- and displacement-reversal landmarks. ER closely reproduces the ABAQUS equilibrium paths. VK remains below a 15 L/t=20 ) and dimensionless left/right rotational flexibilities ( α_0=1 , α_1=2 ) the snap-through-to-looping transition is bracketed by ( f/L= 0.175–0.176) for a homogeneous arch and (0.161–0.162) for an FG arch with ceramic-to-metal modulus ratio ( E^*=E_c/E_m=1.5509 ) and material-gradient index ( p=1 ). The results establish applicability limits for reduced models and extend looping from concentrated or partial loading to full-span vertical loading.
Flows involving hybrid nanofluids and complex suspensions under the influence of magnetic fields play a crucial role in modern thermal and process engineering applications. The present study investigates an unsteady, two-phase magnetohydrodynamic (MHD) flow of a CuO-ethylene glycol–water nanofluid and a couple stress fluid confined between two horizontal parallel plates. The lower region of the channel is occupied by the nanofluid, while the upper region contains the couple stress fluid. A uniform transverse magnetic field is applied normal to the channel walls, incorporating both Hall current and ion-slip effects into the analysis. The governing non-dimensional equations, derived from momentum conservation with interfacial coupling conditions, are solved numerically using the radial basis pseudo spectral (RBFPS) method, which ensures high-order spatial accuracy and smooth convergence. The parametric study explores the influence of the Reynolds number, Hartmann number, viscosity and density ratios, couple stress parameter, Hall and ion-slip parameters, nanoparticle volume fraction, and pressure gradient on the velocity field. Results reveal that increasing the Hartmann number significantly suppresses velocity due to Lorentz force damping, while higher Reynolds numbers and pressure gradients enhance fluid motion. The Hall and ion-slip parameters act to reduce magnetic resistance, leading to higher flow velocities. Moreover, the couple stress parameter and viscosity ratio markedly influence the upper fluid layer, while nanoparticle loading causes minor velocity reduction in the nanofluid region but enhances shear transfer to the couple stress fluid. The RBFPS method provides a stable numerical solution for two-phase flow problems. The outcomes of this study provide valuable physical insight into the control of hybrid MHD flows and offer a reliable computational framework for designing magnetically regulated nanofluid systems used in microchannel cooling, biomedical transport, and thermal energy management applications.
