Porous wind barriers (PWBs) are gradually applied to tunnel–bridge–tunnel infrastructures (TBTIs) along high-speed railway lines. Due to the remarkable aerodynamic effect of high-speed trains (HSTs), the windproof performance of a PWB at tunnel–bridge section (TBS) is particularly critical when a HST passes through the TBTI under crosswind. And it seems to be easily ignored by researchers. This study

The ship hull form optimization using the Computational Fluid Dynamics (CFD) method is increasingly employed in the early design of a ship, as an optimal ship hull form can obtain good hydrodynamics. However, it is time-consuming due to its many CFD simulations for the optimization. This paper presents a ship hull form optimization loop using the surrogate model, deep belief network (DBN), to reduce

Lubrication and cooling performances of face gears with oil–jet lubrication are closely related to the nozzle layouts. To investigate the influence of the nozzle layouts on the lubrication performance of the face gears, a numerical analysis method based on heat-flow coupling is adopted in this study for predicting the transient temperature characteristics. First, a mathematical model of impingement

Turbine guide vane faces extremely high thermal load, especially on the leading edge region. In order to enhance cooling performance, the present study investigates the effects of leading-edge film cooling arrangements by adiabatic and aero-thermal coupled simulation. The three-row cooling design of the 25° inclined angle with the trenched holes is used to replace five-row showerhead holes. The SSTk−ωγ−Reθ

This study numerically investigates the combustion characteristics in a swirl burner for CO-H2 syngas by large eddy simulation. Firstly, experimental data are used to verify the applicability of the Boivin mechanism and the Sandia mechanism. The simulation results show that the Boivin mechanism predicts a more reasonable flame structure. Then, Syngas25, Syngas45, and Syngas100 (composed of 25%, 45%

This paper aims at ensuring the safety of catenary operation, by considering the flow field characteristics of the specific railway terrain and the wind-induced dispalcement of the catanery contact wires. Combining fluid and structure analyses, the improved delayed detached eddy simulation (IDDES) method based on the κ-ω turbulence model was used to explore the flow field characteristics at the position

In this study, a computational fluid dynamics approach based on solving the Reynolds-averaged Navier-Stokes equation and shear stress transport (SST) (Menter) k-ω turbulence model is used to solve the rotor in ground effect. A discrete element method based on solving the Hertz-Mindlin (no-slip) contact model and considering the real physical properties and collision is used to solve the motion and

Gaseous and vaporous cavitation have extremely harmful effects on hydraulic axial plunger pumps, reducing flowrate and increasing flow pulsation. The collapse of vapor bubbles strongly impacts the inner wall and produces many pits. Therefore, it is very important to reduce gaseous and vaporous cavitation to improve the performance of hydraulic axial plunger pumps. In this work, a full cavitation model

ABSTRACT Complex two-phase flow phenomena in wellbores after sour gas kick may lead to severe well control incidents. By bridging the gas solubility, H2S phase transition and flow equations, a two-phase flow model is established under conditions of transient and non-isothermal states in wellbores, which is well validated against the two-phase flow experimental data. The following conclusions are drawn

ABSTRACT Sediment transport in the ejector is highly stochastic and non-linear in nature, and its accurate estimation is a complex and challenging mission. This study attempts to investigate the sediment removal estimation of sediment ejector using newly developed hybrid data-intelligence models. The proposed models are based on the hybridization of adaptive neuro-fuzzy inference systems (ANFIS) with

The evaporation-driven motion and deposition dynamics of nanoparticles (NPs) play significant roles in inkjet-printed structures such as the finger electrodes of solar cells. The objective of the present work is to reveal the mechanisms of NPs motion and distribution on a textured surface in the multi-droplets impact, coalescence and evaporation process. However, the complex interplay among NPs, host

The MENA-CORDEX (the Middle East and North Africa-COordinated Regional Downscaling Experiment) wind speed data at the height of 10 m is converted to the turbine hub-height for estimating the mean wind power in the Gulf of Oman. The results show high spatial variability of the historical and future mean wind power projection. Furthermore, the impact of climate change on the mean wind power (under the

The propeller wake can cause vibrations on the rudder surface, which worsen the noise and reliability. The vibration monitoring of the rudder operating in the propeller wake with fluid-structure interaction (FSI) method is still challenging. In the present study, the structural response during propeller-rudder interaction is investigated using detached eddy simulation. Three-dimensional distributions

Double-unit trains increase passenger capacity but also increase energy consumption. Therefore, research about the aerodynamic resistance of a double-unit train is of great importance to save energy. In this study, a commercial long-marshalling high-speed train and 8 kinds of double-unit trains are used to investigate the effect of the gap length on aerodynamic resistance. The results show that the

Design optimization of transonic airfoils for rotary blades is a challenging subject that remarkably affects the stage and overall performance of axial-flow compressors. This paper describes a surrogate-based multi-objective optimization process over a transonic rotary blade. This blade works in the first high-pressure stage of a pre-designed industrial axial compressor. It experiences a massive separation

ABSTRACT The turbulent convective thermal transfer in channel heat exchangers (CHEs) is studied numerically via the CFD (Computational Fluid Dynamics) method. Deflectors are inserted on the hot bottom walls of the heat channel to enhance the hydrothermal characteristics. Various shapes of in-line deflectors are considered, namely: rectangular (a/b = 0.00), cascaded rectangular-triangular (a/b = 0.25

ABSTRACT Rivers in the north-western region of China have a high sediment content, and the construction of reservoirs on these rivers must address the problem of sedimentation that results in a loss of reservoir capacity. In this study, the YZD (Yazidang) reservoir was considered as a typical case, to address the problem of sedimentation in injection-type water supply reservoirs in Northwest China

This paper presents a coupled heat transfer model for coal-fired boilers that integrates boiler’s fire side computational fluid dynamics (CFD) solution with the boiler’s steam cycle, and thus, can predict the boiler steam temperatures subject to different boiler design and operation conditions. In this coupled model, the heat transfer submodels describing the gas-steam heat exchange for each part of

It is important to optimize the structure of inlet due to the increasing demand of ram air. In this paper, structural optimization of the submerged inlet is pursued using a hybrid model by integrating least squares support vector machines (LS-SVM) prediction model and improved genetic algorithm-particle swarm optimization (GA-PSO). Inlet shape is controlled by changing three-dimensional geometric parameters

ABSTRACT In this study, the unique reverse-flow around the inlet nozzle of a squirrel-cage fan was numerically studied by computational fluid dynamics (CFD), and a non-axisymmetric D-type inlet nozzle was proposed to inhibit it. It is shown that serious back flow develops at the volute tongue when the fan operates at a low flow coefficient that is lower than the best efficiency point. The airflow passing

This study numerically evaluates the performance of flow control using fluidic oscillators on the NACA 0015 airfoil with a flap at different flap angles and different pitch angles of the oscillators. An inline array of fluidic oscillators is located just in front of the flap. Aerodynamic analysis was carried out using three-dimensional unsteady Reynolds-averaged Navier-Stokes equations in a computational

Owing to the strong three-dimensionality and transient evolution, the flow dynamics of a cavitating jet inside a water poppet valve is poorly understood, leading to insufficient basis for exploring the governing mechanism of cavitation effects. In this paper, a three-dimensional simulation considering the compressibility of each constituent phase is performed, to clarify the governing mechanisms under

The present study proposes the hybrid machine learning algorithm of artificial neural network-genetic algorithm-response surface methodology (ANN-GA-RSM) to modelthe performance and the emissionsof a single cylinder diesel engine fueled by diesel and propylene glycol additive. The evaluations areperformed using the correlation coefficient (CC), and the root mean square error (RMSE) values. The best

To design a high-quality vehicle shock absorber, the internal structure of the piston assembly of a shock absorber is analyzed in this study. Using the fluid–solid coupling method, a high-precision flow grid model and a solid finite element model of the stacked valve are built and analyzed. A bidirectional fluid–solid coupling method is proposed, which can be adopted to simulate and analyze the dynamic

A ghost-cell immersed boundary method for unified simulations of flow over finite- and zero-thickness moving bodies at large Courant-Friedrichs-Lewy (CFL) numbers is presented. In order to handle such bodies in a unified manner, algorithms for interface construction and cell demarcation are proposed. The main challenge in treating zero-thickness bodies is to maintain sharpness and accuracy even at

Single blade centrifugal pump is suitable for transporting sewage water with large obstacles in diameter, which is required to achieve high performance. The blade inlet angle is a parameter that affects the performance of the single blade centrifugal pump. However, the selection of blade inlet angle is frequently based on experiences and demonstrates certain arbitrariness. Therefore, six impellers

The pre-swirl system can offer cooling air to improve the extreme thermal shock to the rotating turbine blades in a gas turbine engine. This study focuses on theoretical, experimental, and numerical analyses about the flow and entropy increment for a pre-swirl system at the high-speed test conditions (up to 10000 rpm). Especially, the pre-swirl system entropy increment was firstly measured in the experiment

The efficient removal of material debris by flushing is critical for the performance and the surface quality of the electrical discharge machining (EDM) manufacturing process. The particle concentration alters the thermal, mechanical, and electrical properties of the particle–dielectricum suspension and affects the manufacturing process and the surface quality by inducing high thermal loads. For the

ABSTRACT Wire-mesh sensors (WMSs) have been used to measure various characteristics of bubbles, such as volume fraction, size and velocity. The WMS used in this study consists of a grid of nine by nine wires arranged in an orthogonal shape. Transmitter wires are activated sequentially and receiver wires pick up the electric signals and convert them to a current. Multiphase flow, the electric conductivity

ABSTRACT Both potential and wake interactions are usually the primary mechanisms related to the unsteadiness in turbomachines. However, it is usually difficult to distinguish their effects on flow evolution. This paper develops a direct and visual method to investigate the effects of wake and potential interactions on features of the flow velocity in a two-stage centrifugal refrigeration compressor

Monitoring the water contaminants is of utmost importance in water resource management. Prediction of the total dissolved solid (TDS) is particularly essential for water quality management and planning in the areas exposed to a mixture of pollutants. TDS primarily includes inorganic minerals and organic matters, and various salts and increasing the concentration of TDS causes the esthetic problems

ABSTRACT Accurate prediction of the scour hole depth and dimensions downstream of ski-jump spillways has been an important issue among hydraulic researchers for decades. In recent years, computing methods such as Artificial Neural Networks (ANNs), Adaptive Neuro-Fuzzy Inference Systems (ANFISs) and Support Vector Regression (SVR) have shown a powerful performance in the prediction of scour characteristics

The aim of the paper is to propose a groundbreaking method for the aerodynamic optimization design of the bioinspired wing with leading-edge tubercles. An emphasis on the optimization design of the spanwise waviness in the leading edge for delaying stall and increasing lift from the aerodynamic performance perspective has been laid in this study. For the conversion of the wavy configuration, the form

In the present study, water electrolysis was employed for Hydroxy gas (HHO) production as a gaseous additive. The engine test was performed using the Diesel, B5, and B20 as pilot fuels. HHO was imported into the engine's combustion chamber at three volumetric flow rates of 3, 4, and 5 cc/s through the inlet manifold as the low-level HHO rate.The engine test setup was a single-cylinder dual-fueled diesel

This paper investigates the hydrodynamic characteristic of a single-stage centrifugal pump with inlet inducer and outlet Radial Guided Vanes (RGVs) influenced by the clocking effect for the first time. Different from general ones, the outlet RGVs in this paper have specificities. The hydraulic performance and dynamic characteristics of the centrifugal pump are numerically studied and validated by experiments

ABSTRACT Installing a turbine in a duct generally increases the flow through the rotor. If there is flow confinement due to limited water depth, the presence of lateral boundaries, or the presence of adjacent turbines, a further flow enhancement through the rotor will be achieved. Extensive studies of ducted turbines in uni-directional flow have shown that rotor-based power coefficient C p can exceed

This paper mainly proposed a dynamic control method of particle distribution uniformity in a rolling circulating fluidized bed (RCFB) by using an air distribution plate. An Euler–Euler numerical simulation approach which is called two-fluid flow model is used to simulate the behaviors multiphase flow within the RCFB. Six different tilt angles θ which are θ = 2°, 5°, 8°, 10°, 12° and 15° are used for

ABSTRACT Deviant geometry of nasal channels results in significant changes to nasal aerodynamics that alter flow resistance, sensation, and the ability to filter aerosols. The invasive, operative modification of nasal geometry might alter the intranasal flow patterns, and this must be considered in advance at the stage of surgical planning. The present work describes flow patterns, reproduced numerically

Pre-swirl system is installed to minimize energy loss between the stationary and rotating parts of turbine secondary air system. Although various optimization studies were conducted to increase the pre-swirl efficiency, most of the studies were focused on a hole type pre-swirl nozzles. In this study, a vane type pre-swirl nozzle was optimized to increase mass flow rate and temperature drop for given

Enhancing the efficiency of gear systems is of significance to reduce fuel consumption and overall weight. Windage power losses become prevailing in high-speed gear systems, such as aero-engine applications. To avoid the shortages and limitations of commonly used methods (e.g. negative volume in dynamic mesh method and one moving object in sliding meshing method), this paper describes an unstructured

Compressor design is always a prevalent research issue as nowadays the compressor demands higher performance. Designing afresh a new compressor of higher aerodynamic performance will cost a tremendous amount of time and expense. Consequently, the wiser method of acquiring a higher performance compressor is to optimize a current compressor, discussed in this paper. First, a detailed numerical simulation

In this study, we numerically investigated the effects of CO2 gas in geothermal water and the scale deposition formed in the wellbore on the flow characteristics. Geothermal water that contains CO2 gas has the potential to produce calcite scale deposits in the wellbore. To prevent scale formation, scale inhibitor is injected below the flash point in the wellbore, which is a challenging job. Therefore

Due to industrial development, the volume of carbon dioxide (CO2) is rapidly increasing.. Several techniques have been used to eliminate CO2 from the output gas mixtures. One of these methods is CO2 capturing by ionic liquids (ILs). Computational models for estimating the CO2 solubility in ILS is of utmost importance. In this research, a white box model in the form of a mathematical correlation using

The precise calculation of drag forces in the technical application of automatic balancing of rotating machinery provides important information about efficiency and stability. With increasing geometric complexity of the design, this poses a challenge that can be solved with computer-aided fluid dynamic approaches. In rolling element bearings, the influence of drag induced by the lubricant is predominantly

A new numerical methodology to solve the 3D Navier-Stokes equations for incompressible fluids within complex boundaries and unstructured body-fitted tetrahedral mesh is presented and validated with three literature and one real-case tests. We apply a fractional time step procedure where a predictor and a corrector problem are sequentially solved. The predictor step is solved applying the MAST (Marching

Manning’s roughness coefficient(n) is considered a key parameter in a one-dimensional (1D) hydrodynamic model. However, it is highly variable and time- and site- dependent. Further, identifying proper n values is not easy, especially in plain looped river network areas. Therefore, a more systematic approach is needed. This study proposes a coupled optimization-simulation model to systematically estimate

Numerical modeling of turbulent impinging swirling jets involve complex flow physics that make their computation still very challenging. Thus, the literature on computational modeling of these nanofluid jets is really scarce, with most works on laminar impinging nanofluid jets or turbulent swirling/non-swirling air or water-only jets. In this paper a computational analysis of different configurations

Discretizing and synthesizing random flow generation (DSRFG) is applied to generate inflow turbulence satisfying large eddy simulation (LES) requirements for bridge wind engineering. The variation of the turbulent wind along the computational domain is investigated considering multiple grid sizes and time steps. The aerodynamic admittance functions (AAFs) of a thin plate and two bridge sections are

ABSTRACT The impact of presence of nano-scale particles inside a flow between two flat plates which known as Poiseuille flow is numerically analyzed. Nanofluids have been investigated in the past few years mainly by considering the heat transfer aspect in a fully developed section of internal flows, rather than detailing the hydrodynamic and thermal developing viewpoint of nanofluid. In other words

The turbulence–chemistry interaction model with finite-rate chemistry is a common model for solving supersonic turbulent combustion and takes into consideration the interaction between turbulent mixing and chemical reactions as well as finite chemistry reaction instead of the fast chemistry assumption. However, not only the density and viscosity but also the chemical reactions are affected by the compressibility

This paper has established an evaluation system for the sensitivity analysis of cascade/compressor aerodynamic performance to geometric deviations. The system includes blade profile parameterization with non-uniform rational B-spline (NURBS), uniform Latin hypercube sampling in association with Monte Carlo algorithm and statistical investigation methods. The sensitivity of a subsonic cascade performance

With the increase of the running speed of the high-speed train (HST), aerodynamic interference between the HST and surrounding structures becomes more and more important. Traditional wind tunnel experiments using the stationary model can not fully reveal the pulsing behavior of the aerodynamic forces on both the HST and surrounding structures. This paper numerically investigates the aerodynamic characteristics

Many important technical systems operate according to the principles of momentum transfer, heat transfer and mass transfer near the surface of a cylinder rotating in a confined space. Numerical study of the Taylor–Couette flow with an imposed inward radial throughflow in the rotating inner cylinder demonstrates the possibility of flow stabilization to prevent large-scale vortices up to high rotation

Fluid seepage into rock pores not only generates poroelastic stress but also exerts seepage force on the rock skeleton. However, since the mechanism of the effect of seepage force on the stress field around the wellbore is not clear, conventional methods calculate the stress field only taking into account the poroelastic stress without the coupled effects of seepage force and rock deformation. Based

Ploughbreast is the crucial soil-engaging component of horizontally reversible plough (HRP). Its biggest merit, compared to conventional ploughs, is to enable the ploughbody to perform alternative and shifting tillage operations with high speeds. A major technical challenge in the aforementioned operation is violent flowing interaction between soil and ploughbreast. This flowing interaction may result

To find the influence of the suction chamber and throat inlet profiles on the cavitation performance of an annular jet pump (AJP), a numerical method using a combination of the realizable k–ϵ turbulence model and the Schnerr–Sauer cavitation model was applied. This paper comprehensively studied the cavitation performance of AJPs with a polygonal line profile (POL) and a streamlined profile (STR). The

The failure of tube heat exchangers is an acute problem in industry and, in most cases, is due to the solid particle erosion of a few tubes. Identifying the critical erosion surfaces and thereafter changing the particle impingement pattern on the surfaces is one of the solutions to increase the lifetime of heat exchangers. In this work the fluid flow, solid particle motion and metal erosion of different

The fast and accurate simulation of aircraft wake vortices evolution and safety assessment of wake encounters are important in identifying the hazard zone of wake vortices, reducing wake separation, and increasing the capacity of airports. However, numerical simulation of wake vortices often takes a lot of time due to a large number of grids. In order to reduce the computation time, Solution-Based

Accurate streamflow prediction is essential in reservoir management, flood control, and operation of irrigation networks. In this study, the deterministic and stochastic components of modeling are considered simultaneously. Two nonlinear time series models are developed based on autoregressive conditional heteroscedasticity and self-exciting threshold autoregressive methods integrated with the gene

This study consists of proposing a new mathematical method to develop a new model for evaluating thermal distributions throughout convergent-divergent channels between non-parallel plane walls in Jeffery Hamel flow. Subsequently, dimensionless equations that govern temperature fields and velocity are numerically tackled via the Runge–Kutta-Fehlberg approach based on the shooting method. Additionally