Numerical Simulation of Gas-Dynamic Processes in Model Solid-Propellant Engines

The article presents the results of the development of methodology for the calculation of non-stationary gas dynamics processes occurring in gas dynamic paths of rocket engines and environment at the launch of rockets. The method takes into account the change of geometry of solid fuel combustion surface during the operation of the engine and the change in the geometry of the computational domain taking into account the dynamics of rocket launch. Numerical simulation of gas-dynamic processes of the launch of model solid-fuel rocket was done. The unsteady gas-dynamic flow pattern was investigated. The pressure curve in the solid propellant rocket engine combustion chamber, the speed of movement and overload were determined.

The work for ensure the possibility of validation results for numerical simulation of gas-dynamic processes in a wide range with the use of modern techniques and certified measuring instruments are continued at the hypersonic aerodynamic shock tube facility. The method of precise experimental determination of the dynamic pressure at the critical section of the nozzle was tested. The results of calculations of the pressure field behind the section of the regular and elongated nozzles are validated. Measurements of the stagnation pressure before the nozzle were obtained experimentally.

Numerical simulation of gasdynamic processes occurring with the action of laser radiation with moderate flux density on a metallic barrier in air

The calculation of water-hammer pressure phenomenon of single-phase liquid is already more mature for a pipeline of uniform characteristics, but less research has addressed the calculation of slurry water hammer pressure in complex pipelines with slurry flows carrying solid particles. In this paper, based on the developments of slurry pipelines at home and abroad, the fundamental principle and method of numerical simulation of transient processes are presented, and several boundary conditions are given. Through the numerical simulation and analysis of transient processes of a practical engineering of long-distance slurry transportation pipeline system, effective protection measures and operating suggestions are presented. A model for calculating the water impact of solid and fluid phases is established based on a practical engineering of long-distance slurry pipeline transportation system. After performing a numerical simulation of the transient process, analyzing and comparing the results, effective protection measures and operating advice are recommended, which has guiding significance to the design and operating management of practical engineering of longdistance slurry pipeline transportation system.

The article presents a construction method and an example of a model of a technical object operation process as well as the main stochastic assumption which is a mathematical model of an object state changes. The model of the operation process was built using an analysis of the state space and operation-related events of the analyzed technical objects. An example of numerical simulation of the technical object state change process as a tool to be used to support the analysis of the considered process. Numerical simulation of the stochastic process being a model of a technical object state change process makes it possible to determine the process characteristics impossible to determine in an analytical way.

PurposeThe numerical simulation of practical thermal processes is generally complicated because of multiple transport mechanisms and complex phenomena that commonly arise. In addition, the materials encountered are often not easily characterized and typically involve large property changes over the ranges of interest. The boundary conditions may not be properly defined and or may be unknown. However, it is important to obtain accurate and dependable numerical results from the simulation in order to study, design, and optimize most practical thermal processes of current and future interest. The purpose of this paper is to focus on the main challenges that are encountered in obtaining accurate numerical simulation results on practical thermal processes and systems.Design/methodology/approachA wide range of thermal systems is considered and the challenges faced in the numerical simulation are outlined. The methods that may be used to meet these challenges are presented in terms of grid, solution strategies, multiscale modeling and combined mechanisms. The models employed must be validated and the accuracy of the simulation results established if the simulation is to form the basis for improving existing systems and developing new ones.FindingsOf particular interest are concerns like verification and validation, imposition of appropriate boundary conditions, and modelling of complex, multimode transport phenomena in multiple scales. Additional effects such as viscous dissipation, surface tension, buoyancy and rarefaction that could arise and complicate the modelling are discussed. Uncertainties that arise in material properties and in boundary conditions are also important in design and optimization. Large variations in the geometry and coupled multiple regions are also discussed.Research limitations/implicationsThe paper is largely focused on numerical modeling and simulation. Experimental data are considered mainly for validation and for physical insight.Practical implicationsA wide variety of practical systems, ranging from materials processing to energy, cooling, and transportation is considered.Originality/valueFuture needs in this interesting and challenging area are also outlined in the paper.

The numerical modelling and process simulation for the fault diagnosis of rotary kiln incinerator were accomplished. In the numerical modelling, two models applied to the modelling within the kiln are the combustion chamber model including the mass and energy balance equations for two combustion chambers and 3D thermal model. The combustion chamber model predicts temperature within the kiln, flue gas composition, flux and heat of combustion. Using the combustion chamber model and 3D thermal model, the production-rules for the process simulation can be obtained through interrelation analysis between control and operation variables. The process simulation of the kiln is operated with the production-rules for automatic operation. The process simulation aims to provide fundamental solutions to the problems in incineration process by introducing an online expert control system to provide an integrity in process control and management. Knowledge-based expert control systems use symbolic logic and heuristic rules to find solutions for various types of problems. It was implemented to be a hybrid intelligent expert control system by mutually connecting with the process control systems which has the capability of process diagnosis, analysis and control.

The impacts of environmental changes, such as climate and land use–land cover changes, on the hydrologic system have increased at regional and global scales in the last few decades. As a result, environmental consequences in large-scale river basins, like floods and droughts, and the management of these basins require the understanding of contributing watersheds within the basin. Studying hydrologic processes and numerical simulation and prediction of these processes under the influence of climate changes and human activities within the river basin are crucial to many environmental aspects, such as the development and utilization of water resources, and mitigation of the disasters of floods and droughts. Many programs and projects, such as “The Impact of Climate Change on the Hydrologic Cycle and Assessment of Water Resource Security in the Region of Yellow River, Huaihe River, and Hai River,” have been aimed to evaluate the impact of climate change on the hydrologic cycle, to examine climate change– driven mechanisms of floods and droughts, and to assess the influence of climate change on regional water resources. This special issue consists of a series of papers in different basins. The topics covered by the papers include (1) the assessment of impacts of climate change on hydrologic processes, such as streamflow and sediment transport; (2) the hydrologic response (e.g., evapotranspiration and runoff) to the land use–land cover changes; (3) model development and application of hydrologic simulations; and (4) hydrologic analysis and simulation with the integrated remote sensing and advanced techniques. These studies present recent advances in the fundamental study, numerical simulation, and prediction of hydrologic processes in river basins. The interactive links among the land-surface and subsurface processes and atmospheric processes are very important in current research efforts to understand how perturbed climate conditions (both human-induced and natural) can modify basin-scale hydrologic systems and, in turn, how the modified hydrologic conditions can influence the climatic system. Although many advances in these research areas have been achieved, the comprehensively integrated basin approach with data assimilation and analysis (e.g., satellite and radar data) is required to address various aspects of impacts of environmental changes (e.g., climate change and land use–land cover changes) on the hydrologic system, such as the understanding of hydrologic processes in response to these changes, the representation of basin-scale processes in large-scale climate and hydrology models, and application of these further scientific advances in the basin-scale decision making.

PurposeExperimental results play a crucial role in the validation of mathematical and numerical models for a variety of basic and applied thermal transport problems. The purpose of this paper is to focus on the role played by experimentation in an accurate numerical simulation of thermal processes and systems.Design/methodology/approachThe paper takes the form of a numerical simulation combined with experimentation. The paper presents various circumstances where the numerical simulation may be efficiently combined with experimentation, and indeed driven by experimental data, to obtain accurate, valid and realistic numerical predictions.FindingsThe paper demonstrates validation and accuracy of numerical simulation.Originality/valueThis paper is an important first step in combining experiments and simulation for complex thermal systems.

In this paper we present a splitting algorithm for a numerical simulation of Li-ion battery electrochemical processes. Liion battery consists of three domains: anode, cathode and electrolyte. Mathematical model of electrochemical processes is described on a microscopic scale, and contains nonlinear equations for concentration and potential in each domain. On the interface of electrodes and electrolyte there are the Lithium ions intercalation and deintercalation processes, which are described by Butler-Volmer nonlinear equation. To approximate in spatial coordinates we use finite element methods with discontinues Galerkin elements. To simplify numerical simulations we develop the splitting algorithm, which split the original problem into three independent subproblems. We investigate the numerical convergence of the algorithm on 2D model problem.

Selective Laser Melting (SLM) is a leading additive manufacturing technology capable of producing complex metallic components with high precision. However, the intricate physical phenomena involved, such as rapid melting and solidification, lead to challenges in process control and quality assurance, often resulting in defects like porosity and residual stress. Experimental optimization is costly and time-consuming. Consequently, numerical simulation has become an indispensable tool for understanding the underlying mechanisms and optimizing process parameters. This review synthesizes recent research on the numerical simulation of the SLM process. It summarizes key findings on the modeling of melt pool dynamics, heat transfer, and fluid flow, highlighting the influence of primary process parameters—laser power, scanning speed, and hatch spacing—on the thermal behavior and resulting part quality. The paper discusses various modeling approaches, from continuum-based Finite Element Methods (FEM) to particle-level Discrete Element Methods (DEM), and the application of different heat source models. Key challenges, including multi-scale/multi-physics coupling, computational expense, and model accuracy, are identified. Finally, future research directions are proposed, emphasizing the potential of hybrid physics-based and data-driven models, and the integration of simulation with in-situ monitoring for real-time process control and defect prediction.

This work aims to gain a better understanding of how the rheological properties of printable materials affect their processability, as well as the quality of the final product, which at the end can lead to reducing time and costs of the process and increase product development. As the first step, the proper rheological non-Newtonian models are extracted from experimental studies. Later, three-dimensional numerical simulation of extrusion process is performed in the context of Direct Numerical Simulation (DNS) of governing equations, where the whole physics of fluid motion is taken into account. A finite-volume fractional step approach is used to solve the Navier-Stocks equations on collocated arbitrary meshes. Geometrical volume-of-fluid (GVOF) interface capturing approach is used to resolve the topological changes of the moving interface. The governing equations are solved using High-Performance Computing (HPC) parallel approaches. Besides the contribution of this work to the advancement of numerical techniques applied to multiphase complex flows, obtained results will shed light on the nature of non-Newtonian extrusion process with vast applications in the 3D printer industrial sectors.

Soil freezing is observed throughout almost the entire forested area of the Russian Federarion in winter. The effect of negative temperatures on dusty-clay soils causes a number of adverse processes that change the properties of the soils themselves. One of the most unfavorable of these processes is the accumulation of moisture in soils under the influence of the movement of the freezing front. When freezing, water-saturated clay soils increase dramatically in volume. This leads to the appearance of frost heaving in the active zone of the forest roadbed, which has an extremely adverse effect on the structure of the entire pavement and can lead to damage to the pavement with a sharp deterioration in the transport and operational qualities of forest roads. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The depth of freezing of the pavement and the roadbed is of the greatest importance for predicting frost heaving and developing measures to combat this phenomenon. The article describes the developed system for monitoring the temperature of the road structure to a depth of 3 m and the measurement results which allow us to evaluate the temperature change at different depths from the road surface and determine the freezing depth. A total of 32 sensors have been installed with a step of 10 cm. A numerical simulation of the freezing process of the pavement and the upper part of the roadbed of a forest road has been performed, with the results compared with the indicators of field observations. Good data convergence has been revealed. According to the results of experimental studies, the freezing value has been 173 cm, and according to the results of numerical simulation – 190 cm. The average error in the results of numerical simulation of the freezing process of the pavement and the upper zone of the forest roadbed has been 8–10 % compared to the experimental data.

The development of a digital twin for the engineering process of rotational moulded polyurethane components is presented in this contribution. The digital twin includes the coupling of FE analyses with a novel simulation environment of the rotational moulding process. For the setup of the numerical process simulation, the C++ based open-source software package OpenFOAM is used, which is widely established in research and development for the numerical solution of fluid mechanics problems (Computational Fluid Dynamics, CFD). Based on the Volume-of-Fluid method, a simulation environment called interRoMoFoam representing the rotational moulding process according to the Rock‘n’Roll method has been developed. Within the simulation, the resin distribution calculation is carried out taking the chemo-rheological processes during the curing of the polyurethane into account. Among other determined process-related properties the wall thickness distributions of the hollow bodies can be exported and evaluated in appropriate FE analyses under structural-mechanical aspects, for example. In this way, the results of the process and structure simulations can be used to perform precise design adjustments and an optimisation of the part, the mould for manufacturing the part or the process parameters.

The article considers the issues of digital modeling of dynamic processes in the transmissions of transport vehicles. The purpose of this research was to develop an algorithm for numerical mathematical modeling of dynamic processes in the transmissions of transport vehicles using modern digital software packages. The method includes a systematic approach to the study of dynamic processes during switching, based on modeling the operation of the gearbox together with the internal combustion engine (taking into account its dynamic, speed and load characteristics). The order of application of the MATLab - Simulink, Simscape software packages for numerical simulation of dynamic processes is considered. Using the fundamental blocks of these applications, models of physical components are created: the internal combustion engine, friction clutches, gearboxes, elastic shafts, damping devices, and tractor power transmission control systems. A digital model of the tractor transmission is created, its design scheme is given, and the initial characteristics are set. It was used to simulate dynamic processes in the tractor gearbox. The main attention in this paper is paid to the application of the proposed method for calculating the dynamic processes in the gearbox during gear changes under load with forward and reverse switching, including the simultaneous use of several friction clutches.