The heat supply network bleed valve is located in the steam pipe of the steam turbine heater. When conveying the steam medium of high temperature and high pressure, it impacts the valve disc and pipe wall, resulting i...
The heat supply network bleed valve is located in the steam pipe of the steam turbine heater. When conveying the steam medium of high temperature and high pressure, it impacts the valve disc and pipe wall, resulting in flow-induced vibration and noise of the pipe, resulting in excessive pipeline vibration, which is not conducive to the normal operation of the heat supply network and stable steam supply. In this paper, by using large eddy simulation turbulence theory to study bleed valve disc under different rotation angle operating characteristics, pipe flow field regularity of distribution, and the pressure pulsation of measuring points, the Q criterion is applied to analyze the locomotion mechanism of vortex structure in the downstream flow field of the valve disc, the use of common noise prediction method to calculate the noise of the heat supply network structure features, analysis of the inherent law of flow-induced vibration. It is found that with the increase of the rotation angle of the valve disc, there is an obvious negative pressure center area at the back of the valve disc, and the vortex is formed under the action of the adverse pressure gradient. The decrease in vortex size makes the flow efficiency at the back of the valve increase significantly. Large eddy simulation results show that the fluid generates a double vortex structure similar to the dean vortex behind the valve, and is eventually broken and separated due to the dissipation of viscous turbulent kinetic energy. The smaller the rotation angle is, the more seriously the dissipation vortex blocks the flow area near the pipe wall. The noise characteristics of the flow field in the heat supply network present a dipole state and the overall broadband characteristics. The energy of the flow field is concentrated in the low and middle frequency, and there is a peak of noise SPL. simulation results showed that when the valve disc rotation angle is less than 30°, the vortex structure will seriously b
The proceedings contain 261 papers. The topics discussed include: MBSE-based modeling technology for aircraft assembly tooling design demand;modeling and implementation of distributed rain water storage and utilizatio...
The proceedings contain 261 papers. The topics discussed include: MBSE-based modeling technology for aircraft assembly tooling design demand;modeling and implementation of distributed rain water storage and utilization;modeling free surface elevation around tandem piers of the longitudinal bridge by computational fluid dynamics;L1-finite difference method for inverse source problem of fractional diffusion equation;EMD and singular value difference spectrum based bearing fault characteristics extraction;research on a distribution-outlier detection algorithm based on logistics distribution data;activation detection algorithms for pattern division multiple access uplink grant-free transmission;application of enhanced whale adaptive threshold noise reduction method in transformer ultrasonic 3D imaging detection;human body shape reconstruction from binary image using convolutional neural network;a pricing mechanism which implements allocation in Shannon formula of home cellular wireless communication;and research on power consumption information acquisition system based on broadband power line carrier technology.
This paper proposes a prediction method for non-stationary time series data with time varying parameters. First a modular structured neural network is newly introduced for the purpose of modeling the changing properti...
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ISBN:
(纸本)0780348605
This paper proposes a prediction method for non-stationary time series data with time varying parameters. First a modular structured neural network is newly introduced for the purpose of modeling the changing properties of time varying parameters. This neural network is constructed by the hierarchical combination of each neural network (NNT: Neural Network for Prediction of Time Series data) and a neural network (NNW: Neural Network for Prediction of Weights). Next it is proposed a method to determine the length of the local stationary section by using the additive learning ability of multi-layered neural networks. Finally the validity and effectiveness of the proposed method are confirmed through simulation experiments.
In the flight test data, there usually are abnormal values due to uncertainties in acquisition, storage and transmission. Processing the abnormal values is essential to ensure the accuracy of subsequent test data anal...
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Factor analysis and deconvolution are commonly used tools in analysis of time activity analysis of biological organs in scintigraphic data. Typically, these are used independently such that the output of the former is...
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ISBN:
(纸本)9780889868892
Factor analysis and deconvolution are commonly used tools in analysis of time activity analysis of biological organs in scintigraphic data. Typically, these are used independently such that the output of the former is taken as an input to the latter. Each method is thus unaware of the restrictions imposed by the other and fails to respect them. In this paper, we propose a probabilistic model that integrates convolution into the factor analysis model. We develop an approximate Bayesian estimation of the model parameters based on Variational Bayes approximation. The new variant of the factor analysis model is suitable for modeling of a range of biological processes where convolution kernels are known to have restricted shapes. Properties of the new model are illustrated on analysis of data from dynamic renal scintigraphy. The proposed model provides more realistic estimates of the convolution kernels.
simulation is an effective method to study pedestrian flow. In order to analyze the impact of weave area of building on pedestrian flow, taking advantage of simulation platform based on minimum cost algorithm to simul...
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A static aeroelastic responses analysis method based on mapping external nonlinear aerodynamic forces onto 3D body surface panel elements is proposed. The external nonlinear aerodynamic force data can be obtained by E...
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ISBN:
(纸本)9783037859063
A static aeroelastic responses analysis method based on mapping external nonlinear aerodynamic forces onto 3D body surface panel elements is proposed. The external nonlinear aerodynamic force data can be obtained by Euler solver, Navier-Stokes solver and wind tunnel tests. In this paper, the method is applied to obtain static aeroelastic responses of a flexible aircraft, and the emphasis is placed on the change of aerodynamic coefficient, aerodynamic pressure distribution and flight load. The results are compared with static aeroelastic responses calculated by high-order panel method. It is concluded that the method presented in this study is feasible, credible and efficient, and can provide an assessment of static aeroelastic response characteristics for the detailed stage of aircraft design.
Reliability assessment in mechanized tunneling requires to take into account limited information describing the local geology and the corresponding geotechnical parameters. The geotechnical data are often quite limite...
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When using electrometric method to measure the static strain of a structure, the results are often accurate, but the number of measuring points is limited;when using the finite element method to model and analyze the ...
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ISBN:
(纸本)9783037859063
When using electrometric method to measure the static strain of a structure, the results are often accurate, but the number of measuring points is limited;when using the finite element method to model and analyze the practical structures, there often exist many assumptions of uncertain factors, so the accuracy of simulation results is poor, but the strain values of all the nodes in the grid of simulation structure are available, so the number of measuring points is large. In view of this situation, this paper applied Bayes-Kriging estimation method through the measurement strain data to update the strain on the surface of finite element strain simulation model. We applied the measurement strain data at different stages of the fatigue process to update finite element model. With the comparison of the strain data between before- and after- updating, we can find that at the boundary region and fatigue crack extending direction, the updating result is inaccurate, but the updating effect is good at other position. This method can improve the accuracy of these positions' strain value and make the strain value closer to the actual strain value.
Experimental andcomputational results are presented for a generic scramjet nozzle/afterbody model. Mixtures of Argon and Freon were employed as simulant scramjet exhaust gases because they correctly model the invisci...
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