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The draft tube is one of the main components that integrate a turbine, since it has the function of recovering the residual kinetic energy after the runner by the pressure energy. The search for a draft tube design that increases the efficiency of the turbine is always an engineering challenge. The hydromechanics components geometry optimization can be accomplished through the integration of optimization methods and CFD tools. In this work, the geometric optimization of a double diffuser draft tube of a Bulb turbine applied to ultra-low heads is presented, with the objectives of maximizing the pressure recovery coefficient, Cp, and increasing the hydraulic efficiency of the turbine, ηh. These improvements would make it possible to reduce the longitudinal length of the draft tube, thereby, making an easier insertion of this kind of turbines in water transport systems, with pressures around 3 [mH2O]. The optimization methodology was performed in the meridional plane, using twelve geometric variables in the draft tube through the integration of optimization methods and computational fluid dynamics. The optimized geometry obtained showed an increase in the Cp value of 0.71516, from the original geometry, to 0.83080. The results were extended to the 3D flow analysis, where the optimized turbine showed efficiency gains of 82% to 84%, when compared to the original turbine considering that its total length was reduced and its geometry simplified, resulting in a more compact and versatile equipment. The study also concluded that the applied methodology can be extended to other similar optimization problems in the design of hydraulic machines‎.

The purpose of the investigation was to improve the hydraulic damper valve to meet the automotive customer requirements. The original design was not good enough to achieve the damping forces in the range demanded. The main goal was to lower the minimum achievable forces at the compression stroke by reducing flow restrictions of piston valve. CFD analysis was used to verify proposed variants without the expense of prototyping and experimental testing. Design restrictions of present components were measured on the flow test bench and compared with previously done CFD analysis to ensure a proper correlation with a numerical model. The model was used to predict pressure drop over developed designs.

A transient numerical analysis of natural convection of near-freezing water in a cavity with lateral openings and internal heat sources is carried out to investigate the influence of the heat dissipation rate in the flow configuration. The heat sources were positioned to create buoyancy-opposing and buoyancy-assisted conditions simultaneously and the top and bottom walls are kept at 0◦C. The non-linear dependence of the physical properties with temperature is considered in the governing equations. Based on the heat dissipation rate, six different regimes were observed and classified through a qualitative analysis of the temporal evolution of the velocity and temperature fields. The characteristics of heat transfer for each regime are analyzed to define the most important mechanisms of heat removal. In the upper layer (heated from below), the buoyancy forces eventually overcome the viscous forces and unsteady thermal plumes are formed, in-creasing the heat removal through the openings, while the heat transfer with the top wall is not significant. In the lower layer, the development of wave-like instabilities leads to oscillatory regimes for intermediate heat dissipation rates, while for high dissipation rates a steady convective regime is observed. This behavior increases the heat transfer with the bottom wall, making it much more significant when compared with the upper layer.

Evaluation of store separation experimentally is expensive; time consuming and dangerous as human risks are involved. This results in development of computational methods to simulate the store separation. Store separation studies include store separation simulation and determination of linear and angular displacements of store under the influence of complex and non-uniform flow field of parent aircraft. In order to validate the methodology, the unsteady CFD results, obtained by coupling six degrees of freedom (6-DOF) with flow solver, are compared with experimental results. Major trends are captured which are consistent with experimental results. Variation in store trajectory has been evaluated with different combinations of forward and rearward ejection forces. By increasing the magnitude of forward ejection force vertical displacement increases and store separates more safely from the wing. Moreover, effects of varying parent wing configuration on store trajectory has also been analyzed by incorporation of leading-edge flaps (LEFs). Store always separates in nose down condition due to LEFs which increases vertical displacement of store and thus safety related to store separation is enhanced.

Modern HVAC systems in road vehicles are vital for maintaining thermal comfort, but also represent a significant energy consumer, especially in electric vehicles. This study investigates airflow optimization methods to improve energy efficiency and passenger comfort by combining thermodynamic modeling, CFD simulation, and intelligent control. The paper proposes an integrated approach using adaptive control strategies and advanced cabin design, focusing on dynamic airflow regulation based on real-time sensor input. A simplified mathematical model and CFD analysis were developed to evaluate airflow velocity, temperature distribution, and energy use. The simulation compared standard and optimized configurations, demonstrating that better airflow control reduces energy consumption while maintaining or improving comfort. The results confirm that airflow optimization, through predictive control and smart sensor integration, is a feasible path toward more efficient and sustainable climate control systems in vehicles. The findings support future applications in automotive design, particularly for electric and low-emission vehicles.

The article presents results of research on an adjustable check valve. In particular, the article deals with improvement of flow characteristics and reduction in pressure losses of an existing valve design. The subject of the research was the valve body in the form of a steel block intended for mounting a typical cartridge valve insert. Two variants of the valve body were analysed: a standard one, which is currently in production, and the proposed new solution, in which the geometry was modified based on the results of CFD simulations. The main research task was to properly shape and arrange holes and flow channels inside the body, between the cartridge valve and the connecting plate. Using CFD analyses, a solution for minimising the flow resistance was sought and then the method of modifying flow channels geometry was developed. The CFD simulation results showed a significant reduction in pressure loss, up to 40%. The obtained simulation results were verified on a test bench using a prototype of the proposed valve block. A high degree of consistency in the results of CFD simulations and laboratory experiments was achieved. The relative difference between simulation and experimental results in the entire considered range of the flow rate did not exceed 6.0%.

In this study, we proposed a novel approach to improve centrifugal pump performance with regard to the pump head, pump efficiency, and power. Firstly, to establish constraints, an optimal numerical model that accounted for factors such as pump efficiency and the head was considered. The pump was designed, and an artificial intelligence algorithmic approach was applied to the pump before performing experiments. We considered a set of models by selecting the parameters of the centrifugal pump casing section area, the interference of the impeller, the volute tongue length, and the volute tongue angle. The weights of the factors of safety and displacement on the optimization indices were estimated. The matrix of the weights for the optimal process was less than 38% or greater than 62%. This approach guarantees a complicated multi-objective optimization problem. The results show that the centrifugal pump performances were improved.

In order to further improve accuracy and stability of detection of combustion coal fallout propensity of cigarettes, author of the paper adopted computational fluid dynamics (CFD) technology for a three-dimensional numerical simulation of exhaust system of detection instrument, aiming to study characteristics of flow field near cigarettes. Moreover, a simulation model of eight-channel exhaust enclosure was established, obtaining vector diagram for flow velocity of flow field, velocity contour diagram, and pressure distribution cloud diagram. According to findings, flow field of eight channels is evenly distributed, with slow flow velocity around the instrument but furious inside channels. The wind velocity of cigarette monitoring channel is stable at about 200mm/s specified as per standard. However, there is significant change in pressure and flow velocity at the corners of channels, causing local turbulence. In experiments, average wind velocity of 8 monitoring channels was measured, and simulation results were compared with experiment data. Eventually, a conclusion is drawn that simulation result at cigarette monitoring channels changes consistently with the experimental data, with small errors as a whole. Therefore, the designed exhaust system complies with regulations on wind velocity stipulated by YC/T558-2018 Cigarettes—Determination of Combustion Coal Fallout Propensity of Burning Cigarettes. In a word, this paper is hoped to provide technical support for analogue simulation of exhaust system of cigarette detection instrument, and improve detection accuracy.

When it comes to modern design of turbomachinery, one of the most critical objectives is to achieve higher efficiency and performance by reducing weight, fuel consumption, and noise emissions. This implies the need for reducing the mass and number of the components, by designing thinner, lighter, and more loaded blades. These choices may lead to mechanical issues caused by the fluid–structure interaction, such as flutter and forced response. Due to the periodic aerodynamic loading in rotating components, preventing or predicting resonances is essential to avoid or limit the dangerous vibration of the blades; thus, simulation methods are crucial to study such conditions during the machine design. The purpose of this paper is to assess a numerical approach based on a topology optimization method for the innovative design of a compressor rotor. A fluid-structural optimization process has been applied to a rotor blisk which belongs to a one-and-a-half-stage aeronautical compressor including static and dynamic loads coming from blade rotation and fluid flow interaction. The fluid forcing is computed by some CFD TRAF code, and it is processed via time and space discrete Fourier transform to extract the pressure fluctuation components in a cyclic-symmetry environment. Finally, a topological optimization of the disk is performed, and the encouraging results are presented and discussed. The remarkable mass reduction in the component (≈32%), the mode-shape frequency shift from a fluid forcing frequency, and an overall relevant reduction in the dynamic response around Campbell’s crossing confirm the efficacy of the presented methodology.

Ultra-efficient cars (i.e. Formula One racing cars) are loaded with many different aerodynamic components. They interact to produce highly nonlinear flows, which have a very complex effect on the airflow around the racing car. Clearing up fluid phenomena makes it possible to optimize aerodynamic components effectively. This paper reviews the aerodynamic performance of currently used shapes, as well as the definition of the design constraints for the vehicle. The designs are inspired by formula one cars, especially by Honda F1 Team, but they are adjusted according to the limit conditions of CFD simulation software Ansys CFX, and parameters are scaled accordingly based on the space requirements of this test. A level of velocity at 40 km/h is tested, giving ideas of the full model performance. Results are then compared and discussed to obtain a comprehensive and valid conclusion about the potential improvement in the aerodynamics of road cars, which can be extracted from those ultra-efficient ones.