Numerical research on rock breaking performance of water jet based on SPH

The paper presents an overview of studies of slamming on ship structures. This work focuses on the hull slamming, which is one of the most important types of slamming problems to be considered in the ship design process and the assessment of the ship safety. There are three main research aspects related to the hull slamming phenomenon, a) where and how often a slamming event occurs, b) slamming load prediction and c) structural response due to slamming loads. The approaches used in each aspect are reviewed and commented, together with the presentation of some typical results. The methodology, which combines the seakeeping analysis and slamming load prediction, is discussed for the global analysis of the hull slamming of a ship in waves. Some physical phenomena during the slamming event are discussed also. Recommendations for the future research and developments are made.

Review of ship slamming loads and responses

In the process of rock breaking, the conical pick bears great cutting force and wear, as a result, high-pressure water jet technology is used to assist with cutting. However, the effect of the water jet position has not been studied for rock breaking using a pick. Therefore, the models of rock breaking with different configuration modes of the water jet are established based on SPH combined with FEM. The effect of the water jet pressure, distance between the jet and the pick bit, and cutting depth on the rock breaking performance as well as a comparison of the tension and compression stress are studied via simulation; the simulation results are verified by experiments. The numerical and experimental results indicate that the decrease in the rates of the pick force obviously increases from 25 MPa to 40 MPa, but slowly after 40 MPa, and the optimal distance between the jet and the pick bit is 2 mm under the JFP and JSP modes. The JCP mode is proved the best, followed by the modes of JRP and JFP, and the worst mode is JSP. The decrease in the rates of the pick force of the JCP, JRP, JFP, and JSP modes are up to 30.96%, 28.96%, 33.46%, 28.17%, and 25.42%, respectively, in experiment. Moreover, the JSP mode can be regarded as a special JFP model when the distance between the pick-tip and the jet impact point is 0 mm. This paper has a dominant capability in introducing new numerical and experimental method for the study of rock breaking assisted by water jet and electing the best water jet position from four different configuration modes.

Rock breaking performance of a pick assisted by high-pressure water jet under different configuration modes

In the process of hard rock breaking, the conical pick bears great cutting force and wear, and the cutting efficiency is lower. Thus different combination ways of water jet and conical pick were pr...

https://journals.sagepub.com/doi/pdf/10.1155/2014/868041

Rock Breaking by Conical Pick Assisted with High Pressure Water Jet

In the field of rock breaking, considerable challenges, including high power dissipation, dust, and sharp pick wear, can be solved efficiently by using high-pressure water jet assistance during cutting. Hence, a new high-pressure rotary seal device was designed to stably apply the water jet technology to a roadheader for a rotating speed of 50 r/min and a water pressure of 40 MPa. In addition, three types of cutting heads assisted by the water jet, namely, the center water jet cutting head (CWJCH), the front water jet cutting head (FWJCH), and the rear water jet cutting head (RWJCH) were designed and machined by studying the relative position between the pick and the water jet. Comparative tests of the rock-breaking performance were conducted by varying the water pressure on the three cutting heads and an ordinary cutting head (OCH) at the cutting head test bench. The experimental results show that the CWJCH has the characteristics of minor cutting, advanced resistance, and dust concentration; the FWJCH ranks second in rock-breaking performance. However, in removing dust, the performance of the FWJCH is poorer than the RWJCH. Compared to the OCH, for a water pressure of 40 MPa, the reductions in the cutting resistance, advance resistance, and dust concentration are 40.37, 51.53, and 71.44% for the CWJCH; 30.58, 24.06, and 55.66% for the FWJCH; and 16.56, 34.02, and 70.21% for the RWJCH.

Experimental investigation and application on the cutting performance of cutting head for rock cutting assisted with multi-water jets

The outcomes of a research focusing on water modeling and Fluid-Structure Interaction by ALE and SPH in LSTC/LS-Dyna971 are presented in this paper. Firstly the water impact behaviors of a rigid wedge are modeled with water region by ALE and SPH. The size of fluid elements plays critical role to the numerical results, so three different cases varied in mesh or particle spacing both in ALE and SPH methods are detailed discussed. The numerical results are compared both one to the others and to the experimental and theoretical results in terms of vertical velocity and slamming force, which can be concluded that the more elements modeled in the simulation, the better approximation with the experiment results. An additional discussion of propagation of pressure wave by SPH and CPU time are also presented.

Fluid-Structure Interaction Modeling by ALE and SPH

The impact on water of aeronautical structures is likely to turn into a tragic event. In view of this, it is essential to develop new solutions to design worthy structure that can assure best behavior. The Smoothed Particles Hydrodynamics (SPH) is a mesh-free interpolation method which is a recent numerical analysis technique. One example of water impact based on SPH is presented here, which aims at an accurate numerical simulation of Fluid-Structure Interaction(FSI) in free surface flow context. The example describes a rigid sphere impacting onto water, presenting the global impact behavior as well as comparing the impact coefficient with analytical and experimental results. The SPH method is proved to be a reliable and efficient numerical tool.

Bao Dong Guo

Papers

Fluid-Structure Interaction Modeling by ALE and SPH

Numerical Simulation of Sphere Impacting Water by SPH with Hydrodynamics