To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and th...To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and the compressor are analyzed using full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS)results and the orbit method.It is found that the induced swirl distortion and the mass flux nonuniformity are intensified in the compressor upstream flow field.A correction factor is thus added to the BFM to account for the effect of the induced swirl,which is crucial for the accurate representation of distortion transfer in the intake.Then,steady simulations with large-amplitude 180circumferential total temperature distortion are performed using the developed BFM.It is shown that the distorted compressor map simulated with the BFM matches well with URANS results.The circumferential phase shift of total temperature and the generation of the additional total pressure distortion across the rotor are in line with the time-averaged URANS flow field.The compressor upstream effects on the distorted inflow can also be exactly captured.All above-mentioned results demonstrate the BFM developed in this paper can effectively capture the distorted flow features inside the compressor,and significantly reduce the computational costs by five orders of magnitude compared with URANS.展开更多
In order to improve rolled strip quality, precise plate shape control theory should be established. Roll flat- tening theory is an important part of the plate shape theory. To improve the accuracy of roll flattening c...In order to improve rolled strip quality, precise plate shape control theory should be established. Roll flat- tening theory is an important part of the plate shape theory. To improve the accuracy of roll flattening calculation based on semi infinite body model, especially near the two roll barrel edges, a new and more accurate roll flattening model is proposed. Based on boundary integral equation method, an analytical model for solving a finite length semi infinite body is established. The lateral surface displacement field of the finite length semi-infinite body is simulated by finite element method （FEM） and lateral surface displacement decay functions are established. Based on the boundary integral equation method, the numerical solution of the finite length semi-infinite body under the distribu ted force is obtained and an accurate roll flattening model is established. Different from the traditional semi-infinite body model, the matrix form of the new roll flattening model is established through the mathematical derivation. The result from the new model is more consistent with that by FEM especially near the edges.展开更多
An immersed body boundary method is adopted to track the motions of a towing cylinder, and a homogenous multiphase Eulerian-Eulerian fluid approach is used to capture the free surface. The Reynolds average Navier-Stoc...An immersed body boundary method is adopted to track the motions of a towing cylinder, and a homogenous multiphase Eulerian-Eulerian fluid approach is used to capture the free surface. The Reynolds average Navier-Stockes(RANS) solver is applied to all gird nodes to deal with different velocities of the nodes that are in the body boundary, near the boundary and out of the boundary and their effect on the fluid. The towing cylinder resistance at different submerged depths in the tank is presented. The simulation results are compared with the experimental data, and the method is verified and validated. Finally, the hydrodynamic characters of the cylinder are discussed further. The numerical and experimental results show that at high speeds, the deeper the cylinder submerges, the lower resistance it suffers. The resistance coefficient trough is obtained at Froude number in the range of 0.3 < F r < 0.4. These phenomena can provide some suggestions on the small waterplane area twin hull(SWATH) design.展开更多
A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were...A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were taken into account as source terms of the governing equations without a blade geometry by a body force model. In this model, viscous effects in blade passages can also be calculated directly, which include the exchange of momentum between fluids and detailed viscous flow close to walls. NASA Rotor 37 compressor test rig was used to validate the ability of the body force model to estimate the real performance of blade rows. Calculated pressure ratio characteristics and the distribution of the total pressure, total temperature, and swirl angle in the span direction agreed well with experimental and numerical data. It is shown that the body force model is a promising approach for predicting the flow field of the turbomachinery. Then, coupled axisymmetric mixed compression supersonic inlet-fan simulations were conducted at Mach number 2.8 operating conditions. The analysis includes coupled steady-state performance, and effects of the fan on the inlet. The results indicate that the coupled simulation method is capable of simulating behavior of the supersonic inlet-fan system.展开更多
For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital ...For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital imaging, a simulated annealing algorithm is adopted to expand the meso-structural features of deposit bodies in 3D. The construction of the 3D meso-structure of a deposit body is achieved, and then the particle flow analysis program PFC3 D is used to simulate the mechanical properties of the deposit body. It is shown that with a combination of the simulated annealing algorithm and the statistical feature functions, the randomness and heterogeneity of the rock distribution in the 3D inner structure of deposit body medium can be realized, and the reconstructed structural features of the deposit medium can match the features of the digital images well. The spatial utilizations and the compacting effects of the body-centered cubic, hexagonal close and face-centered packing models are high, so these structures can be applied in the simulations of the deposit structures. However, the shear features of the deposit medium vary depending on the different model constructive modes. Rocks, which are the backbone of the deposit, are the factors that determine the shear strength and deformation modulus of the deposit body. The modeling method proposed is useful for the construction of 3D meso-scope models from 2D meso-scope statistics and can be used for studying the mechanical properties of mixed media, such as deposit bodies.展开更多
To study the safety and stability of large slopes, taking the right side slope of the Yuxi’an tunnel of the Yuchu Expressway Bridge in Yunnan Province as an example, limit equilibrium and finite element analysis were...To study the safety and stability of large slopes, taking the right side slope of the Yuxi’an tunnel of the Yuchu Expressway Bridge in Yunnan Province as an example, limit equilibrium and finite element analysis were applied to engineering examples to calculate the stability coefficient of the slope before and after excavation in the natural state. After comparative analysis, it was concluded that the former had a clear mechanical model and concept, which could quickly provide stability results;the latter could accurately determine the sliding surface of the slope and simulate the stress state changes of the rock and soil mass. The stability coefficients calculated by the two methods were within the stable range, but their values were different. On this basis, combined with the calculation principles, advantages and disadvantages of the two methods, a comprehensive analysis method of slope stability based on the limit equilibrium and finite element methods was proposed, and the rationality of the stability coefficient calculated by this method was judged for a slope case.展开更多
In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the m...In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the matter here, we will see in part 1: about the Galaxy life cycle, where the birth and death of Galaxies discussed. Probably Universe gives guidance for the movement of Galaxies. We call this Part 1: Thinking and Reproducing Universe or Mindless Universe? (Galaxy life cycle). We see every day Sun, Stars, Galaxies etc., dissipating enormous energy in the form of radiation by the way of fusion of Hydrogen to helium. So after sometime all the Hydrogen is spent and Universe will die, is it not? … Dynamic Universe Model says that the energy in the form of electromagnetic radiation passing grazingly near any gravitating mass changes in frequency and finally will convert into neutrinos (mass). Hence Dynamic Universe Model proposes another process where energy will be converted back into matter and the cycle energy to mass to energy continues, sustaining the Universe to maintain this present status for ever in this form something like a Steady state model without any expansion. This we will see in Part 2: Energy - Mass - Energy Cycle. After converting energy into mass “how various elements are formed and where they are formed?” will be next logical question. Dynamic Universe Model says that these various particles change into higher massive particles or may get bombarded into stars or planets and various elements are formed. Here we bifurcate the formation of elements into 6 processes. They are for Elementary particles and elements generated in frequency changing process, By Cosmic rays, By Small stars, By Large Stars, By Super Novae and Manmade elements By Neutron Stars. This we will discuss in Part 3: Nucleosynthesis.展开更多
基金the National Science and Technology Major Project,China(Nos.J2019-Ⅱ-0020-0041 and J2019-Ⅱ-0017-0038)the Science Center for Gas Turbine Project,China(No.P2022-A-Ⅱ-002-001)the National Natural Science Foundation of China(No.52206061).
文摘To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and the compressor are analyzed using full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS)results and the orbit method.It is found that the induced swirl distortion and the mass flux nonuniformity are intensified in the compressor upstream flow field.A correction factor is thus added to the BFM to account for the effect of the induced swirl,which is crucial for the accurate representation of distortion transfer in the intake.Then,steady simulations with large-amplitude 180circumferential total temperature distortion are performed using the developed BFM.It is shown that the distorted compressor map simulated with the BFM matches well with URANS results.The circumferential phase shift of total temperature and the generation of the additional total pressure distortion across the rotor are in line with the time-averaged URANS flow field.The compressor upstream effects on the distorted inflow can also be exactly captured.All above-mentioned results demonstrate the BFM developed in this paper can effectively capture the distorted flow features inside the compressor,and significantly reduce the computational costs by five orders of magnitude compared with URANS.
基金Item Sponsored by National Natural Science Foundation of China(51075353)
文摘In order to improve rolled strip quality, precise plate shape control theory should be established. Roll flat- tening theory is an important part of the plate shape theory. To improve the accuracy of roll flattening calculation based on semi infinite body model, especially near the two roll barrel edges, a new and more accurate roll flattening model is proposed. Based on boundary integral equation method, an analytical model for solving a finite length semi infinite body is established. The lateral surface displacement field of the finite length semi-infinite body is simulated by finite element method （FEM） and lateral surface displacement decay functions are established. Based on the boundary integral equation method, the numerical solution of the finite length semi-infinite body under the distribu ted force is obtained and an accurate roll flattening model is established. Different from the traditional semi-infinite body model, the matrix form of the new roll flattening model is established through the mathematical derivation. The result from the new model is more consistent with that by FEM especially near the edges.
基金Fund of State Key Laboratory of Ocean Engineering of Shanghai Jiao Tong University(No.GKZD010059-22)
文摘An immersed body boundary method is adopted to track the motions of a towing cylinder, and a homogenous multiphase Eulerian-Eulerian fluid approach is used to capture the free surface. The Reynolds average Navier-Stockes(RANS) solver is applied to all gird nodes to deal with different velocities of the nodes that are in the body boundary, near the boundary and out of the boundary and their effect on the fluid. The towing cylinder resistance at different submerged depths in the tank is presented. The simulation results are compared with the experimental data, and the method is verified and validated. Finally, the hydrodynamic characters of the cylinder are discussed further. The numerical and experimental results show that at high speeds, the deeper the cylinder submerges, the lower resistance it suffers. The resistance coefficient trough is obtained at Froude number in the range of 0.3 < F r < 0.4. These phenomena can provide some suggestions on the small waterplane area twin hull(SWATH) design.
基金support of National Natural Science Foundation of China (Nos. 51706008 and 51636001)China Postdoctoral Science Foundation (No. 2017M610742)Aeronautics Power Foundation of China (No. 6141B090315)
文摘A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were taken into account as source terms of the governing equations without a blade geometry by a body force model. In this model, viscous effects in blade passages can also be calculated directly, which include the exchange of momentum between fluids and detailed viscous flow close to walls. NASA Rotor 37 compressor test rig was used to validate the ability of the body force model to estimate the real performance of blade rows. Calculated pressure ratio characteristics and the distribution of the total pressure, total temperature, and swirl angle in the span direction agreed well with experimental and numerical data. It is shown that the body force model is a promising approach for predicting the flow field of the turbomachinery. Then, coupled axisymmetric mixed compression supersonic inlet-fan simulations were conducted at Mach number 2.8 operating conditions. The analysis includes coupled steady-state performance, and effects of the fan on the inlet. The results indicate that the coupled simulation method is capable of simulating behavior of the supersonic inlet-fan system.
基金Projects(51309089,11202063)supported by the National Natural Science Foundation of ChinaProject(2013BAB06B01)supported by the National High Technology Research and Development Program of China+1 种基金Project(2015CB057903)supported by the National Basic Research Program of ChinaProject(BK20130846)supported by Natural Science Foundation of Jiangsu Province,China
文摘For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital imaging, a simulated annealing algorithm is adopted to expand the meso-structural features of deposit bodies in 3D. The construction of the 3D meso-structure of a deposit body is achieved, and then the particle flow analysis program PFC3 D is used to simulate the mechanical properties of the deposit body. It is shown that with a combination of the simulated annealing algorithm and the statistical feature functions, the randomness and heterogeneity of the rock distribution in the 3D inner structure of deposit body medium can be realized, and the reconstructed structural features of the deposit medium can match the features of the digital images well. The spatial utilizations and the compacting effects of the body-centered cubic, hexagonal close and face-centered packing models are high, so these structures can be applied in the simulations of the deposit structures. However, the shear features of the deposit medium vary depending on the different model constructive modes. Rocks, which are the backbone of the deposit, are the factors that determine the shear strength and deformation modulus of the deposit body. The modeling method proposed is useful for the construction of 3D meso-scope models from 2D meso-scope statistics and can be used for studying the mechanical properties of mixed media, such as deposit bodies.
文摘To study the safety and stability of large slopes, taking the right side slope of the Yuxi’an tunnel of the Yuchu Expressway Bridge in Yunnan Province as an example, limit equilibrium and finite element analysis were applied to engineering examples to calculate the stability coefficient of the slope before and after excavation in the natural state. After comparative analysis, it was concluded that the former had a clear mechanical model and concept, which could quickly provide stability results;the latter could accurately determine the sliding surface of the slope and simulate the stress state changes of the rock and soil mass. The stability coefficients calculated by the two methods were within the stable range, but their values were different. On this basis, combined with the calculation principles, advantages and disadvantages of the two methods, a comprehensive analysis method of slope stability based on the limit equilibrium and finite element methods was proposed, and the rationality of the stability coefficient calculated by this method was judged for a slope case.
文摘In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the matter here, we will see in part 1: about the Galaxy life cycle, where the birth and death of Galaxies discussed. Probably Universe gives guidance for the movement of Galaxies. We call this Part 1: Thinking and Reproducing Universe or Mindless Universe? (Galaxy life cycle). We see every day Sun, Stars, Galaxies etc., dissipating enormous energy in the form of radiation by the way of fusion of Hydrogen to helium. So after sometime all the Hydrogen is spent and Universe will die, is it not? … Dynamic Universe Model says that the energy in the form of electromagnetic radiation passing grazingly near any gravitating mass changes in frequency and finally will convert into neutrinos (mass). Hence Dynamic Universe Model proposes another process where energy will be converted back into matter and the cycle energy to mass to energy continues, sustaining the Universe to maintain this present status for ever in this form something like a Steady state model without any expansion. This we will see in Part 2: Energy - Mass - Energy Cycle. After converting energy into mass “how various elements are formed and where they are formed?” will be next logical question. Dynamic Universe Model says that these various particles change into higher massive particles or may get bombarded into stars or planets and various elements are formed. Here we bifurcate the formation of elements into 6 processes. They are for Elementary particles and elements generated in frequency changing process, By Cosmic rays, By Small stars, By Large Stars, By Super Novae and Manmade elements By Neutron Stars. This we will discuss in Part 3: Nucleosynthesis.
