Nowadays, with rising energy prices, energy efficiency is playing an important role in all industries. Differential pressure-based measuring instruments are still widely used instruments with orifice flow meters being the most popular ones. Due to its simplicity, reliability, and ease of maintenance, orifice flow meters are very common measuring instruments in many industries. As these instruments are differential pressure-based instruments, they are increasing energy costs due to increased pressure loss. Conventional single-hole orifice (SHO) flow meters have many advantages but also some disadvantages that are affecting energy efficiency. These disadvantages like higher pressure difference, slower pressure recovery, lower discharge coefficient can be overcome by multi-hole orifice (MHO) flow meters. Computational fluid dynamics (CFD) simulations were used to study energy consumption of both SHO and MHO with four different β parameters. Results showed MHO to be more energy efficient compared to SHO with same β parameter. These results are showing one more advantage MHO have compared to SHO, but further research is needed to make them a drop-in replacement.

Transients in hydropower plants can result in serious disturbances in a plant operation and damage of mechanical and civil components. The best way to prevent such adverse outcomes is to conduct a transient-state analysis using a mathematical model of the hydropower plant system. Based on the collected data on 270 hydropower plants with cross-flow turbines, regression equations were derived that relate a cross-flow turbine specific speed, rated speed, runner diameter and runner width to the rated turbine head and discharge. The obtained equations were used to estimate the turbine performance characteristics using available unit hill charts of three different cross-flow turbines. Finally, the estimated performance characteristics were used to form the boundary condition ‘cross-flow turbine’ within the unsteady 1D mathematical model. The model was validated through case studies by comparing calculated and measured changes in the turbine speed and inlet pressure, induced by sudden load rejection. The difference between the calculated and measured peak pressures was up to 5% during the most critical period, that is, from the moment of load rejection up to the guide vanes closure. In the case of turbine speed, the difference between the peak values was less than 10% in the same period.

This paper aims to introduce readers and future researchers to the field of inertial microfluidics, presenting key principles, forces, and practical applications. By analyzing over 40 studies, the work systematizes the basic hydrodynamic mechanisms influencing particle motion in microchannels: inertial lift force, Dean drag force, and centrifugal force. The theoretical framework explains the role of dimensionless parameters, Reynolds number and clogging ratio λ, in determining stable particle positions and separation efficiency. A tabular overview summarizes the performance of each geometry, straight, curved and serpentine, and highlights their strengths and limitations. Major challenges include minimizing clogging in narrow channels, scaling throughput for industrial volumes, and adapting systems for complex biological samples like blood or environmental mixtures for microplastic removal. Future research directions should focus on hybrid geometries combining straight and curved segments to balance resolution and throughput, numerical optimization using machine learning algorithms to predict particle trajectories, and applications in emerging fields such as single-cell analysis or nanomaterial synthesis. By linking theoretical models, experimental validations, and industrial requirements, this paper serves as a practical guide for researchers designing inertial microfluidic systems tailored to specific separation tasks.

Axial fans are widely used in local and decentralized residential ventilation applications, such as bathroom and toilet exhausts and short-duct ventilation systems, but the turbulent swirling flow they generate can lead to increased hydraulic losses, reduced energy efficiency, and unstable fan operation. This study experimentally investigates the swirling flow produced by the axial fan operating in a straight duct, following the ISO 5801, case B. Original classical probes and one-component laser Doppler anemometry (LDA) were used to measure velocity components at multiple downstream locations. Results show a strong forced-vortex core (i.e., solid body profile) and a highly non-uniform axial velocity profile near the impeller (x/D = 3.35), which homogenizes downstream (x/D = 26.31), indicating significant energy loss. Circulation and swirl number decrease significantly downstream, but residual swirl remains throughout the duct, increasing pressure drops and leading to unstable fan performance. These findings demonstrate that swirl-induced velocity-profile transformations are a major source of inefficiency in residential ventilation systems employing axial fans without flow-straightening devices.

Izložena je upotreba programskog alata LTSpice namenjenog za rešavanje električnih i elektronskih kola za rešavanje problema iz oblasti strujanja fluida u distributivnim cevnim mrežama. Primeni alata prethodilo je istraživanje i uočavanje sličnosti i razlika koje postoje između pojava u oblasti elektrotehnike i mehanike, konkretno mehanike fluida. Ranije uočene, relativno malobrojne sličnosti između ove dve oblasti predstavljale su početni podsticaj za njihovo povezivanje, dok su brojne uočene razlike služile kao dodatna motivacija za dalja istraživanja i utvrđivanja izomorfizma. Takođe, dat je prikaz mogućnosti primene LTSpice-a u rešavanju problema za slučaj strujanja nestišljivog fluida, konkretno vode, u kompleksnim cevnim mrežama.