Railway Engineering Experimental Teaching Research Based on the Combination of Field Experiment and Virtual Reality(VR)Technology——Taking Central South University as an Example

At present,rail transit is developing rapidly in the world,and this means new and changing requirements for the training of talents in railway engineering experiments.Given the current problems of limited laboratory/field instruments for railway engineering experimentsand the safety/administrative difficulties of going to the frontline of railway lines to teach railway engineering experiemnts in the field,the Department of Railway Engineering of Central South University tried to introduce virtual reality(VR)technology to teach students experiments in the field of railway engineering.Through the virtualized experimental methods,students can carry out railway engineering experiments such as;vehicle wheel pair off-axis experiments,track geometry and position detection,etc.by immersive means.It was observed that after performing virtual simulation experiments,students appeared conversant in subsequent field experiments.Thus,VR greatly improves the teaching efficiency of railway engineering experiments.

Experimental study on compression stroke characteristics of free- piston engine generator

The compression stroke characteristics of free-piston engine generator were studied. The numerical model of the compression stroke was established based on thermodynamics and dynamics equation,and the leak loss,heat loss and friction loss were considered. Through solving numerical equations,the in-cylinder pressure of compression stroke under different compression ratios was calculated,energy transfer and conversion process was analyzed,and the calculated results were experimentally verified. The results showed that the actual effective output of electronic energy and the compression energy stored in the com-pressed gas accounted for about 70%. The compression energy gradually increased with the increasing com-pression ratio. When the compression ratio was more than 7. 5,the actual compression energy increased slowly and the energy error between simulation and test decreased.

Research on Experimental Teaching Reform of Railway Engineering under the Training of International Students

The railway engineering major shows extremely strong applicability,with the internationalization of railway engineering teaching and communication,how to solve the problem of cultivating the international students of the railway engineering major experimental teaching is a core problem that the railway engineering majors in universities need to solve at this stage.Through reform,a new type of experimental teaching system for railway engineering specialty was constructed,that is,the experimental course system and content system determined by the international students training program were taken as the core,the construction of teachers,experimental facilities,practice bases and other conditions as the basis,and the system construction and operation organization to build an organic whole composed of four elements for guarantee.It is closely integrated with the theoretical teaching system and relatively independent.It guarantees the realization of the goal of international students training.And it can integrate and optimize the experimental teaching links,content,methods and evaluation system,and build a“gradual experimentprofessional experiment-comprehensive experiment”progressive gradient experiment teaching system.Form a benign pattern of collaborative training of laboratories,practice bases and scientific research bases,mutual promotion of teaching and scientific research,and effectively promote the improvement of students’experimental innovation ability.

Using Hydraulic Engineering Model Experiment to Study the Sediment Trapping Efficiency of Adjustable Check Dam

The construction of fully closed check dam (CD) is a conventional flood prevention mechanism implemented on rivers. Fully closed CDs trap large amounts of sediments in rivers to stabilize the river slopes and control erosion. However, fully closed CDs cannot selectively trap sediment and may easily overflow, causing them to losing their ability to mediate and hold sediments. Previous studies proposed the concept of “breathable CDs”. The researcher introduced metal slit dam (SD) that could be assembled and disassembled quickly and conveniently. Once a CD reaches maximum capacity, operators must ensure that the water channels of the dam are free from blockage. Moreover, they must inspect the internal accumulation conditions of the dam periodically or immediately following heavy typhoon rains. When necessary, either the sediment buildup in the upriver blockage must be cleared, or the transverse structure of the dam must be removed to allow fine particles to be discharged along with a moderate amount of water. These actions can free up the sediment-storing capacity of the dam for the next heavy typhoon rains. In addition, operators should also inspect the damages inflicted on the dam, such as erosion, wear and tear, and deformation conditions. Damaged components should be disassembled and repaired if possible, or recycled and reused. The present study performed channel tests to simulate closed CDs, SDs, steel pipe dam (SPDs), and steel pipe plus slit dam (SPSDs) for 50-year and 100-year frequency floods. Results were then analyzed to determine the sediment trapping (ST) effects of various CDs, the effects of “adjustable CDs”, and the changes of moderated riverbeds.

Verification on Spray Simulation of a Pintle Injector for Liquid Rocket Engine

The pintle injector used for a liquid rocket engine is a newly re-attracted injection system famous for its wide throttle ability with high efficiency. The pintle injector has many variations with complex inner structures due to its moving parts. In order to study the rotating flow near the injector tip, which was observed from the cold flow experiment using water and air, a numerical simulation was adopted and a verification of the numerical model was later conducted. For the verification process, three types of experimental data including velocity distributions of gas flows, spray angles and liquid distribution were all compared using simulated results. The numerical simulation was performed using a commercial simulation program with the Eulerian multiphase model and axisymmetric two dimensional grids. The maximum and minimum velocities of gas were within the acceptable range of agreement, however, the spray angles experienced up to 25% error when the momentum ratios were increased. The spray density distributions were quantitatively measured and had good agreement. As a result of this study, it was concluded that the simulation method was properly constructed to study specific flow characteristics of the pintle injector despite having the limitations of two dimensional and coarse grids.