Length Of Transition Section Research Articles

Analysis of structure-induced performance in photothermal methane dry reforming reactor with coupled optics-CFD modeling

Structural design and optimization are important for improving the overall performance of solar reactors. In this study, a coupled optics-CFD model was established to simulate the complex processes of radiation absorption, mass and heat transfer, and chemical reactions in a solar methane dry reforming reactor. The effects of structural parameters on the photothermal chemical conversion process were mainly discussed. It is found that slight changes of structural parameters, such as inclined angle and length of transition section, and cut-off ratio and acceptance half-angle of compound parabolic concentrator, could affect the radiation heat flux density distributions greatly and thus leading to significant variation of the chemical reaction. Therefore, special attention should be paid to the coupled analysis of optics and fluid dynamics when designing and optimizing the solar-type reactor. The proposed model and the obtained results are of guiding significance for the study of various solar-thermochemical and photochemical reactors.

Analysis on the Parameter of Transition Section of Metro Trapezoidal Sleeper Track

The length of transition section of Metro trapezoidal sleeper track bed affects the overall stiffness of the track. This paper establishes the Metro vehicle-rail coupling model and compares the calculated results of the trapezoidal sleepers of different transition lengths with the field measured data to verify the correctness of the model. The calculation results show that: The maximum vertical displacement of the track bed at the length of 0, 3, 6, and 9 meters is 2.55, 2.53, 2.01, and 1.92 mm, respectively, the maximum vertical displacements of the transition rails at the length of 0, 3, 6, and 9 meters are 2.53, 2.44, 2.31, 2.30 mm, respectively, the maximum rotation angles of the 0, 3, 6, and 9 meters transition sections are 1.01 rad ‰, 0.96 rad ‰, 0.90 rad ‰, 0.84 rad ‰, respectively. Considering the safety of the track and other factors, the length of the trapezoidal sleeper transition section should not be less than 9m.

Numerical simulation of strength failure of buried polyethylene pipe under foundation settlement

Polyethylene (PE) pipes have a great ability to resist deformation, which is one of the important reasons that PE pipes are used more and more widely in urban gas transportation systems. In this paper, a numerical simulation was conducted in ABAQUS, for the most commonly used PE pipe of DN110-SDR11, under the action of foundation settlement. The situation that PE pipe is perpendicular to settlement section was considered. The variation of piping stress vs settlement displacement was analyzed, and influence of length of transition section on pipe yielding was discussed. It was found that the maximum Mises stress of PE pipe increases with the increment of settlement displacement, but the location is changing, and the dangerous section occurs at the junction of transition section and subsidence area or the junction of transition section and non-subsidence area. Pipe yielding was taken as the failure threshold, and the maximum settlement displacement under which PE pipe serves safely was analyzed. With increasing length of transition section, the settlement displacement for pipe yielding increases, that is PE pipe with longer length of transition section is safer than those with shorter one under the same settlement displacement.

Study on Reasonable Length of Ballasted-CRTS II Ballastless Track Transition Section on High-Speed Railway Bridge

In view of ballasted-CRTSⅡ ballastless track transition section on the bridge of Beijing-Shanghai high-speed railway, the influence of track random irregularity and pier foundation settlement difference on acceleration and stability index of locomotive body are discussed by the finite element method. And then, by using the index of rail deflection gradient to describe the law of dynamic interaction, rail-wheel dynamic response, attenuation distance of locomotive body acceleration and change of sleeper pressure caused by under-rail stiffness difference are analyzed. Finally, the recommended value of reasonable length of transition section is put forwarded.

Application of the Off-Line Simulation System of the Ship Maneuvering in Transition Section Navigation Research of the Continuous Bend

The mathematical model of ship maneuvering is the core of the ship maneuvering off-line simulation system, it establishes three degrees of freedom motion control equation of the rigid body dynamics , in which the ship as a rigid body. Using MMG (Ship Maneuvering Mathematical Model Group) detached method, it considers the role of force and torque as well as the three mutual influences of hull, propeller and rudder respectively, than it applies runge-kutta method to solve differential equations and combine them with matlab programming languages. According to the rotation test and Z-style test of the kiloton ship, the ship maneuvering offline simulation system is proved to be correct and reliable. So we use this system to simulate the movement of ship passing through the continuous meandering bend in different situations. Then, we analyze rudder angle, drift angle and channel width of ship traveling through the continuous meandering bend, and we can find that when the length of transition section is less than 160m, the rudder angle and drift angle which ship is sailing across the after bend are obviously bigger than that of front bend; when the length of transition section increase a certain length, navigational parameter of front bend and after bend are basically the same, however, when it continues to increase, navigational parameter of front bend and after bend will not change and it will remain steady. Then, we define that the length is the critical navigation length of transition section. At the same time, we also can find that the minimum navigable length of transition section increase with the central angle of bend increase, and it will decrease with bending radius increase. When the central angle of bend is more than or equal to ninety degrees, the standard formula results must be certain modified.

A seismic design method for subsea pipelines against earthquake fault movement

As there are no specific guidelines on design of subsea pipelines crossing active seismic faults, methods for land buried pipelines have been applied to. Taking the large seismic fault movement into account, this paper proposes improved methods for seismic designs of subsea pipelines by comprehensively investigating the real constraining of soil on the pipelines, the interaction processes of soil with the pipeline, the plastic slippage of the soil, and the elastic-plastic properties of the pipeline materials. New formulas are given to calculate the length of transition section and its total elongation. These formulas are more reasonable in mechanism, and more practical for seismic design of subsea pipelines crossing active faults.

Analysis of Piecewise Uniform Oval Rings with Transition Sections

An analysis of a doubly symmetric oval ring fabricated from uniform, dissimilar, circular segments connected by a smooth transition section is presented. The ring is subject to a uniform radial load applied on an oval reference line. For several ovals the stress distribution is determined for various lengths of transition section. For each oval there is found an optimum length of transition section as well as a length for which the stress at the foot of the transition section vanishes.