scholarly journals Bubble evolution in the titanium alloy melt under vertical centrifugal field

2020 ◽  
Vol 40 (2) ◽  
pp. 16-23
Author(s):  
Qin Xu ◽  
Xing Wang ◽  
Shiping Wu
Keyword(s):  
Rotational Speed ◽  
Complex Geometry ◽  
Initial Position ◽  
Blocking Effect ◽  
Migration Process ◽  
Centrifugal Field ◽  
Bubble Generation ◽  
Complex Cavity ◽  
Liquid Titanium ◽  
Bubble Evolution

The bubble evolution in the liquid titanium melt under vertical centrifugal field has been studied by the hydraulic experiment simulation. The bubble migration process in the simple and complex cavities, the bubble morphology, bubble dimensional size diversification under different mould rotational speed has been investigated. The results show that the mould wall has a blocking effect on the bubble migration. The bubble migration in the simple cavity deviates from the line between the bubble initial position and the rotation shaft of the casting mould. Also, the bubbles in the complex cavity gather, re-nucleate and form new big ones for the blocking effect of the complex geometry shape on the radial movement of the bubble. The shape of bubbles in both the simple and complex cavity during the migration process is not a perfect sphere, but an elliptical shape. The critical size of bubble released from the bubble generation chamber decreases with the increment of the mould rotational speed. The diameter of the gas bubbles in the simple cavity during the migration process become bigger and bigger for the pressure difference at different positions of the cavity in the vertical centrifugal field.

scholarly journals Hydraulic Study of Bubble Migration in Liquid Titanium Alloy Melt during Vertical Centrifugal Casting Process

2019 ◽  
Vol 38 (2019) ◽  
pp. 309-316
Author(s):  
Qin Xu ◽  
Xing Wang ◽  
Shiping Wu
Keyword(s):  
Centrifugal Casting ◽  
Gas Bubbles ◽  
Casting Process ◽  
Initial Position ◽  
Gas Bubble ◽  
Bubble Generation ◽  
Mould Wall ◽  
Line Parallel ◽  
Complex Cavity ◽  
Liquid Titanium

AbstractThe bubble migration in liquid titanium melt during vertical centrifugal casting process has been investigated by hydraulic experiments. Results show that the gas bubble in the simple cavity ultimately migrates like a line parallel to the wall in the opposite direction to the rotational casting mould. The deviation distance of the bubble in the simple geometry cavity tends to increase with the increment of the mould rotational speed during the migration process. And the gas bubble is much easier to migrate like a line when its initial position is nearer to the casting mould wall which is opposite to the mould rotational direction. The migration trajectories of bubbles located at different position in the complex cavity are more complicated than that in the simple cavity. The casting mould in the complex cavity can hamper both the radial movement and the circular movement of the bubble. And gas bubbles will gather, re-nucleate and form new bigger bubbles beside the casting mould wall. The re-formed gas bubbles in the complex cavity become bigger than which escape from bubble generation chamber.

Three-dimensional seismic crustal structure of the Monashee hinterland core complex on the Lithoprobe Southern Canadian Cordillera Transect

1995 ◽  
Vol 32 (10) ◽  
pp. 1531-1540 ◽  
Author(s):  
Kris Vasudevan ◽  
Frederick A. Cook ◽  
Rolf Maier
Keyword(s):  
Crustal Structure ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Canadian Cordillera ◽  
Metamorphic Complex ◽  
Migration Process ◽  
The South ◽  
Core Complex ◽  
South Central ◽  
Early Tertiary

Three-dimensional seismic coverage in an approximately 12 km × 12 km area of the southern Monashee metamorphic complex in the south-central portion of the Canadian Cordillera reveals a complex geometry to the Mesozoic–early Tertiary contractional Monashee décollement. Data were acquired as part of the Lithoprobe Southern Canadian Cordillera Transect where two approximately perpendicular lines intersected on the south flank of the Monashee mountains in the hinterland of the Cordillera. Stacks of traces within 100 m × 100 m bins are nominally 6-fold, but range from zero to 108-fold due to the crooked nature of the lines. Both migrated and unmigrated data have been examined for interpretation, but the highly variable data quality and discontinuous reflectivity cause excessive added noise during the migration process.

Enhanced CFD Modelling and LDA Measurements for the Air-Flow in an Aero-Engine Front Bearing Chamber: Part II

2014 ◽  
Author(s):  
J. Aidarinis ◽  
A. Goulas
Keyword(s):  
Pressure Drop ◽  
Rotational Speed ◽  
Ball Bearing ◽  
Complex Geometry ◽  
Computational Study ◽  
Air Flow ◽  
Mathematical Form ◽  
Operational Parameters ◽  
Aero Engine ◽  
Flow Through

A detailed computational study of the air-flow through the outer gap of the front bearing of an aero-engine is presented. The reason to carry out this study was to understand the flow through the bearing as a function of the operational parameters of the engine, which was necessary for the modeling of the flow in the whole bearing chamber. The complex geometry and the size of the bearing gap relative to the overall dimensions of the bearing chamber and the need for very precise and detailed information of the effect on the flow within the chamber of the bearing operational parameters, prohibited the solution of the flow through the gap together with the rest of the bearing chamber. A 3-D modeling of the flow through the outer bearing gap, which included a section of the ball bearing, was performed. Functions relating the pressure drop of the air coming through the bearing gap and the tangential component of velocity of the air exiting the bearing region, to the mass of air through the gap of the ball bearing and the rotational speed of the shaft were developed. The effect of the lubrication oil within the bearing was modeled as an anisotropic porous medium with a predefined law. In order to acquire in a mathematical form the above relationships a series of computational runs were performed. These relationships, in the form of second order curves, were subsequently introduced to the model of the bearing chamber as described in [1]. The constants of the relationships were derived through comparisons of the calculations with the experimental data. From the analysis it was concluded that the pressure drop across the bearing increases with the square of the rotational speed of the shaft with the mass flow of air through the ball bearing as a parameter and vice versa. For this particular ball bearing there is a region where, for any combination of rotational speed of the shaft and pressure drop through the bearing, there is no flow of air through the bearing. In this paper the detailed modeling methodology, the computational flow field, the boundary conditions and finally the results are presented and discussed.

PLASMA CORTICOSTEROID LEVELS AND ADRENAL ASCORBIC ACID AFTER INTRAVENOUS CORTICOTROPHIN INJECTIONS AND »STRESSFUL« STIMULI IN THE RAT

1962 ◽  
Vol 39 (4) ◽  
pp. 527-538 ◽  
Author(s):  
Pavo Hedner ◽  
Claus Rerup
Keyword(s):  
Ascorbic Acid ◽  
Abdominal Surgery ◽  
Response Curve ◽  
Significant Rise ◽  
Blocking Effect ◽  
High Dose ◽  
Ascorbic Acid Concentration ◽  
Unilateral Adrenalectomy ◽  
Subcutaneous Injections ◽  
Hypophysectomized Rats

ABSTRACT Measurements of plasma corticosteroid levels and adrenal ascorbic acid concentration in steroid blocked and hypophysectomized rats were performed. It was found that prednisolone and dexamethasone were effective in blocking endogenous corticotrophin release within 3–4 hours after subcutaneous injection. These agents also prevented completely the normally occurring rise in plasma corticoid levels after exposure of the rats to ether. Abdominal surgery (unilateral adrenalectomy) resulted in a slight but significant rise in plasma corticoid levels in spite of dexamethasone blockade. The values of adrenal ascorbic acid were not affected significantly. The blocking effect of two daily subcutaneous injections of a high dose of dexamethasone persisted for about one week after the last injection. The sensitivity of the plasma corticoid response was essentially the same in hypophysectomized and dexamethasone blocked rats. The lower part of the log dose response curve was found to be clearly non-linear in the plasma corticoid method following intravenous corticotrophin injection. As a consequence the dose level in quantitative assays of intravenously injected corticotrophin are, in our hands, of the same order as in the adrenal ascorbic acid depletion method.

A New Computational Procedure to Predict Transient Hydroplaning Performance of a Tire

2001 ◽  
Vol 29 (1) ◽  
pp. 2-22 ◽  
Author(s):  
T. Okano ◽  
M. Koishi
Keyword(s):  
Complex Geometry ◽  
Fluid Flows ◽  
Computational Procedure ◽  
Vehicle Body ◽  
Fluid Viscosity ◽  
Safe Driving ◽  
Transient Phenomena ◽  
Vehicle Velocity ◽  
Fixed Reference ◽  
Volume Method

Abstract “Hydroplaning characteristics” is one of the key functions for safe driving on wet roads. Since hydroplaning depends on vehicle velocity as well as the tire construction and tread pattern, a predictive simulation tool, which reflects all these effects, is required for effective and precise tire development. A numerical analysis procedure predicting the onset of hydroplaning of a tire, including the effect of vehicle velocity, is proposed in this paper. A commercial explicit-type FEM (finite element method)/FVM (finite volume method) package is used to solve the coupled problems of tire deformation and flow of the surrounding fluid. Tire deformations and fluid flows are solved, using FEM and FVM, respectively. To simulate transient phenomena effectively, vehicle-body-fixed reference-frame is used in the analysis. The proposed analysis can accommodate 1) complex geometry of the tread pattern and 2) rotational effect of tires, which are both important functions of hydroplaning simulation, and also 3) velocity dependency. In the present study, water is assumed to be compressible and also a laminar flow, indeed the fluid viscosity, is not included. To verify the effectiveness of the method, predicted hydroplaning velocities for four different simplified tread patterns are compared with experimental results measured at the proving ground. It is concluded that the proposed numerical method is effective for hydroplaning simulation. Numerical examples are also presented in which the present simulation methods are applied to newly developed prototype tires.

Pengembangan Sistem VOIP Menggunakan Server Issabel Versi 4.0 dan Tunnel EOIP pada OMNI Hospital Alam Sutera

2018 ◽  
Vol 18 (1) ◽  
pp. 13-20
Author(s):  
Elly Mufida ◽  
David Wardana Agus Rahayu
Keyword(s):  
Operating System ◽  
Open Source ◽  
End Of Life ◽  
Communication System ◽  
Communication Protocol ◽  
The Internet ◽  
Migration Process ◽  
Web Browser ◽  
Backup Path ◽  
E Mail

The VoIP communication system at OMNI Hospital Alam Sutera uses the Elastix 2.5 server with the Centos 5.11 operating system. Elastix 2.5 by the developer has been declared End of Life. The server security system is a serious concern considering that VoIP servers can be accessed from the internet. Iptables and fail2ban applications are applications that are used to limit and counteract those who try to attack the VoIP server. One application that can be used as an open source VoIP server is the Issabel Application version 4.0. The migration process from Elastix 2.5 application to Issabel 4.0 by backing up all configurations in the Elastix 2.5 application through a web browser including the configuration of endpoints, fax, e-mail, asterisk. After the backup file is downloaded then upload the backup file to the Issabel 4.0 application then run the migration process. Adding a backup path as a failover connection is needed because the VoIP communication protocol between the OMNI Hospitals Group still uses one path so that when there is a problem in the connection path, the communication protocol will stop. The tunnel EoIP is a protocol used as a backup path between the OMNI Hospitals Group site.

Sign in / Sign up

Export Citation Format

Share Document