Experimental Study on the Permeation and Migration Rules of Pressurized Water in Textile-Reinforced Concrete (TRC)

As a new type of repairing and reinforcing material, textile-reinforced concrete (TRC) is often used to improve mechanical properties and durability of offshore, port, and hydraulic structures in the corrosive environment. In order to investigate how to quantify the permeability performance of TRC under external pressurized water, standard concrete permeability tests, nuclear magnetic resonance (NMR) tests, and scanning electron microscope (SEM) tests were conducted. These tests considered the effects of fiber grid size, Tex content, and water–cement ratio on the impermeability of TRC. Experimental results show that water gathers around the fiber bundles and migrates upwards along the longitudinal fiber under external water pressure and seeps out from the upper surface of the concrete specimen. Furthermore, based on the concentric annular slit flow theory and hydropower similarity principle, this study established a formula for the permeability of TRC and the calculated values are in good agreement with the experimental values.

Structural dynamic response analysis due to the slit flow between the tailplane and the elevator

Any aircraft in flight is subjected to dynamic loads. Following vibration-related accidents, a flow field and vibration analysis can be carried out to analyze the data and study the cause of the accident. When slit airflow enters the cavity between the tailplane structure and the elevator, a mixed vortex is formed. If the vortex-induced vibrational frequency of around 50 Hz happens to be close to the natural frequency of the structure at 46 Hz, it is likely to induce structural vibration (resonance). The resonance can cause excessive fatigue damage which can ultimately lead to structural failure and the loss of the component or the aircraft. Damping methods can be employed to control vibration within the structure by reducing the amplitude of that vibrational motion by 83%. This article details a recreation of one example of structural vibration within an airborne aircraft.

Resistance force pulsations of annular flow in the Couette-Taylor system with counter-rotating cylinders

The paper presents the results of an experimental study of the Couette-Taylor flow fluctuations in a ring channel with oppositely rotating multicylinder rotors. Experiments were carried out using water-glycerine solutions as a working fluid. The rotation resistance moment and its pulsations were investigated, using the system for measuring the torque resistance of rotation of rotors, made in the form of a digital dynamometer based on a tension sensor. The investigations made it possible to establish that the classic dependence of the appearance of Taylor vortices is observed in the slit flow of a multicylinder system rotating oppositely. It was shown that in the range of Reynolds numbers Re = (100 – 500), pulsations of dissipative processes with variable frequency and amplitude up to 10% of the mean value of rotation resistance are observed.

Study on Gas Entrainment From Unstable Drifting Vortexes on Liquid Surface

Gas entrainment (GE) from cover gas, which is an inert gas to cover Sodium coolant in a reactor vessel, is one of key issue for Sodium-cooled fast reactors (SFRs) design to prevent unexpected effects to core reactivity. In this study, evaluation method has been investigated for surface dimple depth growth of unstable drifting vortex dimples on the liquid surface in the reactor vessel. By using a computational fluid dynamics (CFD) code, analyses have been conducted to estimate the drifting vortexes on water experiments in the circulating water tunnel. The unstable drifting flow vortexes on the water surface were generated as wake vortexes behind a plate obstacle. Downward flow velocity was induced by bottom slit flow pass along the flow channel. In CFD analysis, flat water surface assumption was used with free-slip model for the development of a conventional design method. The gas core lengths from the surface vortexes were evaluated based on existing non-dimensional numbers method by using the stream-viewer code provided from Japan Atomic Energy Agency (JAEA). In this paper, the results of comparison between experiments and analyses were discussed.

Application of the Finite Piece Method to Simulate Viscoelastic Fluid Flows in L-Shaped Channel

The finite piece method is established to solve the flows of K-BKZ fluid in L-shaped channel. Numerical results are given to compare to the three-dimensional simulation using the finite element method (FEM). It is found that the results are highly consistent as a whole. The error of flow distribution is smaller than 2% at the outlet. There is a minor discrepancy of the pressure in the convergence region of channel but they are restricted to a small region. The present approach demonstrates its superiority over the conventional FEM for analyzing slit flow.