Numerical simulation of the behavior of kinematically unstable slopes under dynamic influences

Introduction. The concept of estimating the dynamic parameters of the “base — weakened layer — block” system is proposed, taking into account the physical nonlinearity of the material and the kinematic method of excitation of vibrations. In accordance with this approach, the physical nonlinearity of the base and block material is considered using the Drucker- Prager model. The weakened layer is modeled by 3D spring finite elements. The verification procedure of the proposed methodology is carried out on the example of the dynamic calculation of the “base — weakened layer — slope” system.Materials and Methods. The computational experiments were performed using the ANSYS Mechanical software package in combination with a nonlinear solver based on the Newton-Raphson procedure. SOLID45 volumetric finite elements were used to discretize the computational domains. Combined elastic-viscous elements COMBIN14 were used to simulate the displacement of the block relative to the fixed base.Results. An engineering technique for the dynamic analysis of the stress-strain state of the “base — weakened layer — block” spatial system with kinematic method of excitation of vibrations is developed. The accuracy and convergence of the proposed method is investigated using specific numerical examples.Discussion and Conclusion. Based on the mathematic simulation performed, it is shown that the developed technique provides assessing the risks of the occurrence of real landslide processes caused by external non-stationary impacts.

Dynamic Calculation of Electric Propulsion Motor Tandem Rotors

The article presents the results of modeling the dynamic response of the tandem rotors of ice-class vessel electric propulsion motors under extreme operating conditions. The loading of rotors by torques in combination with vibration transmitted through the supports to the electric motors is considered as an external non-stationary action. A method for constructing a three-dimensional finite element model of the structure under study by fragmentary assembly has been developed on the basis of the ANSYS Mechanical software package. A scheme of elastic-compliant 3D-links allowing simulating the reciprocating-rotational vibrations of a tandem of rotors is presented. A test example is used to verify the proposed mechanical-mathematical model of the torsion system. Based on the calculated data, the analysis of the dynamic parameters of the tandem rotors is performed for the most unfavorable operating scenarios.

Parametric modeling compressed ellipsoid of rotation as the analytic surface

The article deals with the shaping of the analytical surface in the form of a compressed ellipsoid of rotation. In the process of research, the principle of the golden section was applied, an ellipsoid of rotation with optimal parameters for the design of a large-span unique building of the exhibition complex was obtained. To solve the problem of choosing a rational analytical surface in the Lira-CAD software package, three variants of constructive solutions for the frame of the exhibition complex have been developed. The finite element method is used, the most popular numerical calculation method for studying the stress-strain state of large-span buildings and structures. The analysis of the calculation results made it possible to choose the optimal variant of the structural solutions of the building frame. The check of the dynamic characteristics of the proposed structural solution of the building frame is carried out. The obtained results of the dynamic calculation showed the correctness and efficiency of the adopted structural solutions of the building frame.

Dynamic Analysis for a Reciprocating Compressor System with Clearance Fault

In order to explore the failure mechanism of a reciprocating compressor system with clearance fault, we implemented a computational framework whereby a simulation model of the mechanism is established using ADAMS software in this paper, and a typical reciprocating compressor model is introduced to validate the design model. In this work, the joint clearance faults between the crankshaft and linkage, between the linkage and crosshead, and in both locations are taken into account computationally. These faults are one of the major causes of vibration. Through dynamic calculation and analysis of a system with clearance fault, the simulated results show that these clearance faults directly influence the vibration. The larger the gap size, the more severe the vibration and the higher the amplitude of the vibration. Furthermore, the clearance number also affects the vibration greatly.

A Distributed Virtual Reality System Based on Real-Time Dynamic Calculation and Multi-Person Collaborative Operation Applied to the Development Of Subsea Production Systems

To train inexperienced workers for the construction, production, and maintenance of subsea production systems, a virtual reality simulation platform was developed. The entire framework, software, and hardware platforms of the system were designed and introduced. A multi-person collaborative simulation was achieved based on the high-level architecture protocol. The real-time dynamic calculation software Vortex was used to add physical properties to each geometrical model and set collision detections and motion constraints so that the VR system can reflect the real motion response of the structures in real-time during virtual simulation. Visual simulation software Vega Prime and Vortex were integrated to realise the real-time rendering and drawing of virtual ocean engineering scenes. Thus, a virtual simulation system with large-scale complex scenes based on real-time dynamic calculation and multi-person collaborative operation was established. A typical ocean engineering case of subsea manifold installation was simulated using the virtual simulation system, and the detailed simulation flow was explained. A multibody dynamics system of the ship-cable-subsea manifold was established using Orcaflex to obtain the accurate motion response of the subsea manifold during lowering. In the virtual simulation process, the obtained hydrodynamic calculation results can provide an important guideline and reference to the operators. The developed simulation system is a suitable tool for training ocean engineering workers and realistically simulating ocean operation cases.

The influence of the last stage blades swirl to the efficiency of «stage-diffuser» unit of stationary GTU

THE PURPOSE. Determination of the optimal law of swirling of the blades of the last stage of a stationary GTU. Due to the specificity of its operating conditions - in a system with a diffuser - the traditional laws of swirling lead to a non-optimal flow in the diffuser and, consequently, reduce the efficiency of the entire unit and the power plant as a whole. In this paper, we used numerical and experimental methods for studying a three-dimensional flow. Two stages with different laws of swirling were investigated - with the traditional law of constancy of the angle of flow out of the guide vanes along the radius, and with reverse swirling. The same diffuser was used in both cases. METHODS. Experimental studies were carried out using pneumometric five-channel probes of an original design on an ET-4 aerodynamic stand in the Turbomachinery laboratory of SPbPU. Numerical studies were carried out in the CFX gas dynamic calculation package; the parameters in the corresponding sections, obtained during the physical experiment, were used as boundary conditions.RESULTS. Integral characteristics of the stage, the vector of flow velocities in various sections were obtained. The experiment was compared with the numerical calculation and showed satisfactory convergence of the results. CONCLUSION. The optimal swirling law for the last stage operating in a system with a diffuser is forced vortex flow.

Исследования турбокомпрессоров с общим рабочим колесом для применения в двигателях и энергоустановках

The article deals with the working processes in flowing part of the turbo-compressors with general impeller (TCG) and with two schemes of the flows. The work studies the features of the TCG operation with two schemes of the flows and the gas-dynamic calculation theory development of their flow parts for use in engines and power plants. The tasks to be solved are to investigate two schemes of the flows in the interscapular space of the impeller – direct-flow and counter-flow. If the gas and air flow directions coincide concerning the axis of rotation of the impeller, then the flow pattern in the TCG is direct-flow, with the opposite movement of flows – is counter-flow. The solution to this problem was performed using the developed methods of gas-dynamic calculation of the TCG flow parts. Conclusions. The scientific novelty of the results obtained is as follows: parameters that significantly affect the efficiency of the turbine and compressor parts of the TCG were established and the formula in the form of a general criterion ratio was calculated. The dependence of the correction factor is determined, which considers the effect of the ratio of the impeller width on the average diameter of the working channel of the RK in the compressor section and the turbine section of the TCG. The article contains formulas, with correction factors, for calculating the power factor in the compressor section and the load factor in the turbine section. If the ratio of the grating width to the average diameter of the working channel is overestimated, it is necessary to supplement the formulas with a correction factor that considers the effect of this ratio. Studies have determined that switching from one mode of operation to another – in a certain section of the impeller, accelerates the flow to the required speed. It is especially evident in the compressor working channel of the TCG with a counter-flow pattern. In the turbine section, the gas flow acceleration time does not depend on the flow pattern – the flow is active and accelerates to the required speed in the nozzle apparatus. The given formulas allow calculating the power of the turbine and compressor parts of the impeller to perform an enlarged gas-dynamic calculation of TCG. Studies have determined that TCG can be used in gas turbine engines and the pressurization system of an internal combustion engine.