Experimental study of the effect of various collision angles and critical conditions on marine engine’s twin-spray collision process

To enhance the fuel-gas mixing and phase transition process, the fuel is injected by twin injectors in a large-bore low-speed two-stroke marine engine, while the cylinder condition has reached the transcritical and supercritical conditions. The twin-injector configuration has a great potential for further optimization, but the exploration on the outcome of collision and phase transition was still limited. Therefore, this work aims to study the effect of various collision angles (60°, 90°, 120°, 150°) and critical conditions (sub/trans/supercritical) on the twin-spray collision process using optical techniques. A wide range of experimental cases are conducted to provide an analysis and database for future modeling validation. The post-collisional spray structures, spatial distribution, and periphery features are analyzed to characterize the droplet’s collision. The results show that with the collision angle increasing, the higher collision velocity enhances the mass transfer while the minor vertical component results in a smaller axial dispersion. Because of the trade-off relationship between the vertical velocity component and pre-collision penetration, a higher reduction in droplet momentum results in a slighter collision behavior. At the collision angle of 150°, the subcritical condition tends to result in an off-axis collision. Under the transcritical (P) condition, the probability of head-on collision increases and presents a wider spatial distribution. But under the supercritical condition, because of the existence of the liquid collision, the thermal conversion among phases is accelerated, while the ambient resistance is reduced. Moreover, an exponential correlation of collision liquid length is formulated to predict the axial dispersion based on various critical conditions.

New crack generation phenomena by crack collision in 10 mm thick tempered glass

High speed photography by Caustics method using Cranz–Schardin camera was used to study crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. New crack generation by two crack collision was observed. Regarding the presence/absence of new cracks, the dependence of the two cracks on the collision angle was confirmed. Considering that it is based on the synthesis of stress 𝜎CR generated at the crack tip, tensile stress necessary for the generation of new cracks could be created.

Analysis of the Damage of Cyclists in Electric Bicycle - Sedan Angle Collision

In order to study the vulnerable factors of the traffic accidents—the cyclist's injury factor at the moment of the accident—the computer simulation analysis method is used to restore the information collected by a real accident combined with the scene. From the established multi-rigid kinematics model, the corresponding injury situation of a body structure of a traffic accident rider is obtained, which involves the collision speed, the collision angle, the acceleration of each part of the human body and the force. The data is compared with ECE R44, FMVSS 213 and Euro NCAP 2009 regulations to analyze and restore various factors of bicycle injury in the collision. The results show that when the car and the non-motor vehicle have a low-angle collision, the cyclist's injury is mainly caused by the collision with the ground after the parabola movement, and the damage position of the human body depends on the order of contact with the ground.

On the Structural Behaviour to Penetration of Striking Bow under Collision Incidents between Two Ships

This work addressed the evaluation of collision angle and indenter on the behaviour of target object. A series of collision scenarios based on the mentioned parameters were calculated using finite element method. In the analysis process, several striking ships of different sizes relative to the struck ship are deployed as the collision angles ranging from 0° to 180° are taken into consideration. The results relative to the angles show that the perpendicular collision or a collision angle of 90° produces the lowest level of the internal energy in the side collision category by comparison with oblique collisions in the range of collision angles from 30° to 150°. The internal energy is found to be satisfactory when it is compared with the extent of the damage on the outer shell, which is also matched with the predicted energy behaviour from energy formulae.

Comparing Structural Casualties of the Ro-Ro Vessel Using Straight and Oblique Collision Incidents on the Car Deck

Roll on-roll off (Ro-Ro) ship is the preferable vessel for public transportation and also as a medium to distribute several commodities. Its operations are a straightforward process but traffic management is quite delicate, especially for cross-route. Moreover, maritime incidents sometimes occur, causing significant casualties and in the case of the Ro-Ro, collision with other ship is a possible threat with the ability to trigger immense damages. This research, therefore, was conducted to assess the structural casualties of a Ro-Ro vessel under collision. This was modelled with respect to a ship involved in a certain incident in Indonesia in the latest decade, and the designed collision problems were calculated using the finite element approach. The collision angle was selected as the main input parameter with the straight collision of angle 90° and oblique collision with different angles applied to the scenario. The results found the collision energy due to structural destruction to have distinct pattern and peak value under oblique cases with lower values observed for straight collision for all scenarios. It is, however, recommended that energy should be taken as an initial parameter in further investigation of structural damage and response contour.

Plastic Flow of Aluminum in Explosive Welding

Joining of metals in explosive welding takes place as a result of their plastic deformation during a high speed collision and is usually accompanied by typical formation of waves at the interface. In welding aluminium, the weld boundary can also be straight if the speed of the contact point is νc is ≤ 1900 m/s. These welding conditions make it possible to prevent melting of the metal at the interface and increase at the same time its corrosion resistance. In this article, the effect of the dynamic collision angle on the special features of plastic flow of the metal in the vicinity of the contact boundary in welding sheets of AS5 aluminium is described.