Effect of Nozzle Outlet Type On the Flow Field Velocity and Impact Pressure of High Pressure Water Jet Peening

Author(s):  
Hong-xiang Zheng ◽  
Yun Luo ◽  
Jing-Yu Zang ◽  
Qian Zhang

Abstract Water jet peening can effectively improve the fatigue strength of metal materials, and the outlet shape of nozzle greatly affects the effect of water jet peening. In this paper, the effects of nozzle outlet shape on water jet velocity and impact pressure is studied by numerical simulation, and the jet velocity and dynamic pressure for different standoff distances are also discussed. The results show that the water jets of square, circular and triangular nozzles are highly concentrated, and the water jet of elliptical nozzles is the most divergent. The axial velocity attenuation of the square nozzle along the axis is slower than that of the other three nozzles. The water axial velocity of the elliptical nozzle attenuates fastest and the length of the core segment of the water jet is the smallest. Within a certain axial distance, the dynamic pressure area in the central area of the elliptical water jet is obviously larger than that of the other three nozzles, and the effective treatment range is large, which is more suitable for the welding surface strengthening operation.

Author(s):  
Hong-Xiang Zheng ◽  
Yun Luo ◽  
Bao-Zhu Zhang ◽  
Wen-Chun Jiang ◽  
Shan-Tung Tu

Water jet peening is a good potential method to control welding residual stresses. The water jet with elliptical nozzle can improve the treatment efficiency due to its large treatment area. In this article, the water jet velocity and dynamic pressure for different elliptical nozzle dimensions and standoff distances are discussed by numerical simulation. The results show that when the axial distance is 10 mm, the effective impact diameter of the elliptical nozzle a/b=8–12 is about 2 times or more than that of the circular nozzle. The length of the jet core of the elliptical nozzle is only related to the outlet structure and is independent of the inlet pressure. The correlation between the dimensionless core length of the elliptical water jet and its long and short axes is derived. When the ratio of the major axis to the minor axis is between 7 and 13, the core length of the elliptical water jet is 7–7.5 times that of its minor axis. Combining the suitable treatment area and dynamic pressure, the elliptical nozzle with an axis ratio of 8 is recommended to control the welding residual stress. Finally, a new formula for calculating dynamic pressure distribution is proposed for the elliptical nozzle water jet at different stages.


2013 ◽  
Vol 448-453 ◽  
pp. 1173-1178 ◽  
Author(s):  
Xing Dong ◽  
Wei Yang ◽  
Hai Lu Zhang

In order to achieve movement rule of post-mixed water jet outflow field, post-mixed water jet peening nozzle flow field were simulated by FLUENT software, according to their turbulent characteristics, the mathematical model adopted Euler model, turbulence model adopted the standard kε model. Analyzed the peening pressure and peening standoff distance on the influence of outflow field of liquid-solid two phases-flow axial dynamic pressure and axial velocity, the results show that in different peening pressure, water flow field and pill flow field of axial velocity and the axial dynamic pressure both are symmetrical distribution, and their value increased with the increase of peening pressure to raise, decreases with the increase of peening standoff distance, even, with the increase of length of pill nozzle water flow field of axial velocity decreases, and pill flow field of axial velocity increases. When the peening pressure is 14 MPa, peening standoff distance is 30 mm, length of pill nozzle is 55 mm, maximum axial dynamic pressure of the outflow field is 3.18 MPa, the maximum axial velocity of water flow field and pill flow field respectively are 71.3 m/s and 69.6 m/s.


Zootaxa ◽  
2021 ◽  
Vol 4933 (4) ◽  
pp. 527-542
Author(s):  
PETER DEGMA ◽  
HARRY A. MEYER ◽  
JULIANA G. HINTON

A new Tardigrada species, Claxtonia goni sp. nov. is described from specimens collected in the central area of the Haleakalā National Park, the island of Maui, Hawaii, U.S.A. The new species and Clx. pardalis (Degma & Schill, 2015) together with several examples of Clx. wendti (Richters, 1903) are the only known Claxtonia species with the plates having an intracuticular pattern resembling that on a leopard’s fur. Claxtonia goni sp. nov. differs from Clx. pardalis in the absence of pores on leg plates, in smaller and uniform pores on dorso-lateral plates, in very unequally spaced teeth in the dentate collar, in lesser ratio of internal cephalic cirrus and lateral cirrus A lengths, and in relatively shorter claws in fourth pair of legs. The differences between the new species and the other congeners as well as Echiniscus species with the same cirri composition and similar cuticular sculpture are also defined. The diagnosis of the genus Claxtonia is amended and three Echiniscus species are transferred into the genus with the proposed new combinations: Claxtonia aliquantilla (Grigarick, Schuster & Nelson, 1983) comb. nov., Clx. mosaica (Grigarick, Schuster & Nelson, 1983) comb. nov. and Clx. nigripustula (Horning, Schuster & Grigarick, 1978) comb. nov.. 


2007 ◽  
Vol 329 ◽  
pp. 353-358 ◽  
Author(s):  
Kazushi Minaki ◽  
Koichi Kitajima ◽  
Yu Nakahira ◽  
K. Minaki ◽  
Moriyasu Izawa ◽  
...  

Recently, wet blasting is generally used such as liquid honing and water jet machining in surface before plating of stainless steel. The outstanding feature of wet blasting is to prevent generation of static electric charge, to use micro abrasive grain, and to have cushioning for workpiece. On the other hand, the disadvantage of wet blasting is to generate corrosion of equipment and liquid waste under processing. Moreover, the using abrasive grain is available on a limited basis. In particular, improvement disposal of liquid waste under processing is crucial in the near future. This paper makes proposal for improvement of surface texture by utilizing dry blasting, and it conducts improvement of surface texture about martensite stainless steel (SUS420J2 In JIS), which is used in material for scale. In the previous report, it has been cleared that relationship between surface texture and wettability. In this report, adhesion of plating was measured by scratch test. As a result, it was cleared that availability of adhesion evaluation by utilizing wettability.


2020 ◽  
Vol 19 (1) ◽  
pp. 6-12
Author(s):  
G. Ya. Kostyuk ◽  
O. G. Kostyuk ◽  
M. V Burkov ◽  
I. A. Golubovsky ◽  
M. P. Bulko ◽  
...  

The article highlights the mechanism of the mathematical model of acinus, the components of the formation of pressure in its cavity and the formation of pancreatic juice. It has been established that the mechanism for creating pressure in the acinus cavity is similar to the intraductal one. In this case, the question remains open about the causes of such high pressure, which is measured in several hundred millimeters of a mercury column, especially since, as histologically established, the pancreas and its ducts do not have muscle structures, and those rudiments of myofibrils, which are noted in some places of the flow system, of course, cannot ensure the development of such pressure. The increase in pressure in the cavity of the acinus is associated with the phenomenon of osmosis in its cells. Since cell membranes have the property of conductivity, as a result of osmosis, water through the membrane first passes from the blood to the cell, then from the cell through the membrane into the acinus cavity. In addition to the mechanism of osmosis through the membrane, in the cells of the acinus epithelium, there is a filtering mechanism through the pores of the layer of connective tissue to the lymph channel. It has now been established that, together with simple osmosis, the phenomenon of electroosmosis takes place in secreting cells and organs of excretion, not only accelerates the transfer of substances, but also increases the pressure on the other side of the membrane against the gradient by almost several first-order units. Thus, the outflow of fluid from the acinus cavity proceeds continuously, but only with a change in the speed of movement, it is determined by the pressure drop in the acinus – tubule – excretory duct system, the opening of the Oddi sphincter and the pulse of the cardiovascular wave, which creates dynamic pressure in the capillary. This whole mechanism, as a result, leads to the filling of the cavity of the acinus and the creation of a certain pressure in it.


2021 ◽  
Vol 72 (2) ◽  
pp. 335-345

Abstract At the eastern border of the Carolingian Empire two different groups of elite emerged. When referred to, the individuals in one of the groups were called either by personal names, or by the name of the area they governed; individuals in the other group were called by the name of their people. Members of the first group administered the territorial units of the central area of the former Avar Khaganate just like the Carolingian chief officials and royal vassals in the interior of the Empire. The members of the second group were (indirect) allies of the Avars and had their own tribal prince and gentile nobles. The administrative centres of the Carolingian province Pannoniae developed in synchrony with the inner centres of the Empire, while the centres of power outside the Empire had their own special settlement structures showing a conglomerate of the courts of the tribal nobility.


Author(s):  
John R. Baker ◽  
Keith E. Rouch

Abstract This paper presents the development of two tapered finite elements for use in torsional vibration analysis of rotor systems. These elements are particularly useful in analysis of systems that have shaft sections with linearly varying diameters. Both elements are defined by two end nodes, and inertia matrices are derived based on a consistent mass formulation. One element assumes a cubic displacement function and has two degrees of freedom at each node: rotation about the shaft’s axis and change in angle of rotation with respect to the axial distance along the shaft. The other element assumes a linear displacement function and has one rotational degree of freedom at each node. The elements are implemented in a computer program. Calculated natural frequencies and mode shapes are compared for both tapered shaft sections and constant diameter sections. These results are compared with results from an available constant diameter element. It is shown that the element derived assuming a cubic displacement function offers much better convergence characteristics in terms of calculated natural frequencies, both for tapered sections and constant diameter sections, than either of the other two elements. The finite element code that was developed for implementation of these elements is specifically designed for torsional vibration analysis of rotor systems. Lumped inertia, lumped stiffness, and gear connection elements necessary for rotor system analysis are also discussed, as well as calculation of natural frequencies, mode shapes, and amplitudes of response due to a harmonic torque input.


Author(s):  
Greg Pasken ◽  
J. Ma ◽  
Muhammad P. Jahan ◽  
Shuting Lei

Abstract The most common problem when machining titanium using traditional metal cutting processes is that tools rapidly wear out and need to be replaced. This study examines the ability of a pure water jet to machine Ti-6Al-4V via simulations using ABAQUS’s Smoothed Particle Hydrodynamics (SPH). These simulations are then validated experimentally at two pressures, 138 MPa and 317 MPa. Using a Maxiem water jet built by Omax, experiments are conducted by creating a series of 5 lines that are 5 inches (127 mm) long placed 0.5 inches (12.7 mm) apart on a 1 mm thick Ti-6Al-4V workpiece. Predictive modeling is also conducted using the two additional pressures 400 MPa and 621 MPa as well as three orifice diameters 0.254 mm, 0.3556 mm, and 0.4572 mm. The simulations are validated at both pressures and had a percent error less than 2.6% which were within the standard deviation of the experimental results. The predictive modeling indicates that the pressures above 317 MPa create a near identical percent increase from the orifice diameter but the kerf has a more noticeable decrease in width of cut as the pressure increases. The 138 MPa has the smoothest surface profile compared to the other pressures. The volume of removed material decreases as the pressure increases but the material removal rate (MRR) increases as the pressure increases. This is due to the velocity of the water increasing as the pressure increases causing a lower run time. The 621 MPa is the best pressure to machine Ti-6Al-4V as it has a better MRR than the other pressures used in the predictive modelling.


Zootaxa ◽  
2008 ◽  
Vol 1923 (1) ◽  
pp. 1-17 ◽  
Author(s):  
MAURO RAMPINI ◽  
CLAUDIO DI RUSSO ◽  
FRANCESCA PAVESI ◽  
MARINA COBOLLI

Description of five new Dolichopoda species from the Ionian area of Western Greece together with a description of the female for D. pavesii from Kefalonia island and the male of D. dalensi from North-eastern Peloponnisos are reported. Considering the other 6 species already documented in the area (including the North of the Peloponnisos), there is now a total of 11 recorded species of Dolichopoda which currently inhabit the underground areas of this zone. These new data, therefore, help better define the already high diversity of the genus in the Hellenic region (25 species in all) reinforcing the hypothesis that there was a central area of dispersion of the Dolichopoda in the ancient Aegean plate.


Sign in / Sign up

Export Citation Format

Share Document