Coolant Channel and Flow Characteristics of MQL Drill Bits: Experimental and Numerical Analyses

2017 ◽  
Author(s):  
Yi-Tang Kao ◽  
Behrouz Takabi ◽  
Mozheng Hu ◽  
Bruce L. Tai
Keyword(s):  
Flow Structure ◽  
High Speed ◽  
Critical Role ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Minimum Quantity Lubrication ◽  
Drill Bits ◽  
Mist Flow ◽  
Oil Concentration ◽  
Computational Analyses

In minimum quantity lubrication (MQL) machining, mist flow plays a critical role in both lubrication and cooling. This paper aims to characterize the mist flow structure of different coolant channel designs for through-tool MQL drilling. Two different channel geometries (circular and triangular cross-section) and two sizes of each channel were selected for both experimental and computational analyses. The flow structure was captured by a high-speed camera and explained using computational fluid dynamics (CFD). The results showed that, for all the channel geometries, higher oil concentration was found close to the drill center. Specifically, in the triangular channel, the flow tends to accumulate at three corners. This study also measured the airspeed, which increased with the hydraulic diameter of the channel. These results have demonstrated the effects of channel geometry and the feasibility of using CFD in mist flow analysis.

Characterizing Mist Distribution in Through-Tool Minimum Quantity Lubrication Drills

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jay K. Raval ◽  
Yi-Tang Kao ◽  
Bruce L. Tai
Keyword(s):  
High Speed ◽  
Minimum Quantity Lubrication ◽  
Flow Distribution ◽  
Critical Factor ◽  
Helix Angle ◽  
Distribution Analysis ◽  
Low Velocity ◽  
Minimum Quantity ◽  
Drill Bits ◽  
Mist Flow

Abstract The mist distribution is a critical factor in through-tool minimum quantity lubrication (MQL) drilling since a small amount of lubricant is used. However, it has rarely been discussed because of the difficulty in measuring the mist flow experimentally. In this paper, an optical approach is developed to approximate the mist distribution by using high-speed images from multiple angles. Drill bits with two through-tool channel shapes (circle and triangle) and three helix angles (0 deg, 30 deg, and 45 deg) are 3D printed for mist distribution analysis. Furthermore, computational fluid dynamics (CFD) is conducted to investigate the underlying physics behind mist flow variations. The results show that, in the circular channel, the mist is concentrated near the periphery; the low concentration region shifts away from the chisel point as the helix angle increases. For the triangular channel, the mist is concentrated near three vertices but is less affected by the helix angle. Furthermore, based on the CFD solution, high mist concentration tends to be in low-velocity regions and vice versa. This study confirms a noticeable difference of mist flow distribution in different through-tool channel designs.

Flow Analysis of a Shrouded Aerosol Sampling Inlet

2013 ◽  
Vol 347-350 ◽  
pp. 3903-3906
Author(s):  
Bao Qing Wang ◽  
Shu Yao ◽  
De Qing Wang ◽  
Zhi Peng Bai ◽  
Xin Hua Wang
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Aerosol Sampling

A shrouded aerosol sampling inlet has been designed from high-speed aircraft. The sampling inlet was conducted using the CFD to perform a flow simulation. The shroud diameter is 150 mm. The inlet is located 180mm from the shroud entrance plane. The shroud is 300 mm long. Results are presented graphically, showing the shrouds have provided significant improvements in flow characteristics. Straighten the streamlines of gas of sampling inlet for flow angles up to five degrees. It is suggested that CFD simulation can be useful for improving the optimum a shrouded aerosol sampling inlet.

scholarly journals Random pore structure and REV scale flow analysis of engine particulate filter based on LBM

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 881-896
Author(s):  
Chunrui Wu ◽  
Tiechen Zhang ◽  
Jiale Fu ◽  
Xiaori Liu ◽  
Boxiong Shen
Keyword(s):  
Single Channel ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Particulate Filter ◽  
Random Structure ◽  
Structure Generation ◽  
Inlet Flow ◽  
Random Structures ◽  
Boltzmann Method

Abstract In this article, lattice Boltzmann method (LBM) is used to simulate the multi-scale flow characteristics of the engine particulate filter at the pore scale and the representative elementary volume (REV) scale, respectively. Four kinds of random wall-pore structures are considered, which are circular random structure, square random structure, isotropic quartet structure generation set (QSGS), and anisotropic QSGS, with difference analysis done. In terms of the REV scale, the influence of different inlet flow velocities and wall permeabilities on the flow in single channel is analyzed. The result indicates that the internal seepage laws of random structures constructed in this article and single channel are in accordance with Darcy’s law. Circular random structure has better permeability than square random structure. Isotropic QSGS has better fluidity than anisotropic one. The flow in single channel is similar to Poiseuille flow. The flow lines in the channel are complicated and a large number of vortices appear at the ends of channel with high inlet flow rate. With the increase of inlet velocity, the static pressure in channel gradually increases along the axial direction as well as the seepage velocity. The temperature field in the channel becomes more uniform as the flow velocity increases, and the higher temperature distribution appears on the wall of the porous media.

scholarly journals Additively Manufactured Parts Made of a Polymer Material Used for the Experimental Verification of a Component of a High-Speed Machine with an Optimised Geometry—Preliminary Research

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 137
Author(s):  
Artur Andrearczyk ◽  
Bartlomiej Konieczny ◽  
Jerzy Sokołowski
Keyword(s):  
Polymer Material ◽  
High Speed ◽  
Numerical Models ◽  
Flow Analysis ◽  
Experimental Tests ◽  
Strength Analysis ◽  
Compressor Wheel ◽  
Operational Characteristics ◽  
3D Printed ◽  
Novel Method

This paper describes a novel method for the experimental validation of numerically optimised turbomachinery components. In the field of additive manufacturing, numerical models still need to be improved, especially with the experimental data. The paper presents the operational characteristics of a compressor wheel, measured during experimental research. The validation process included conducting a computational flow analysis and experimental tests of two compressor wheels: The aluminium wheel and the 3D printed wheel (made of a polymer material). The chosen manufacturing technology and the results obtained made it possible to determine the speed range in which the operation of the tested machine is stable. In addition, dynamic destructive tests were performed on the polymer disc and their results were compared with the results of the strength analysis. The tests were carried out at high rotational speeds (up to 120,000 rpm). The results of the research described above have proven the utility of this technology in the research and development of high-speed turbomachines operating at speeds up to 90,000 rpm. The research results obtained show that the technology used is suitable for multi-variant optimization of the tested machine part. This work has also contributed to the further development of numerical models.

RANS and Large Eddy Simulation of Internal Combustion Engine Flows—A Comparative Study

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Xiaofeng Yang ◽  
Saurabh Gupta ◽  
Tang-Wei Kuo ◽  
Venkatesh Gopalakrishnan
Keyword(s):  
Large Eddy Simulation ◽  
High Speed ◽  
Combustion Engine ◽  
Flow Analysis ◽  
Partial Geometry ◽  
Computational Domain ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rans Simulations

A comparative cold flow analysis between Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) cycle-averaged velocity and turbulence predictions is carried out for a single cylinder engine with a transparent combustion chamber (TCC) under motored conditions using high-speed particle image velocimetry (PIV) measurements as the reference data. Simulations are done using a commercial computationally fluid dynamics (CFD) code CONVERGE with the implementation of standard k-ε and RNG k-ε turbulent models for RANS and a one-equation eddy viscosity model for LES. The following aspects are analyzed in this study: The effects of computational domain geometry (with or without intake and exhaust plenums) on mean flow and turbulence predictions for both LES and RANS simulations. And comparison of LES versus RANS simulations in terms of their capability to predict mean flow and turbulence. Both RANS and LES full and partial geometry simulations are able to capture the overall mean flow trends qualitatively; but the intake jet structure, velocity magnitudes, turbulence magnitudes, and its distribution are more accurately predicted by LES full geometry simulations. The guideline therefore for CFD engineers is that RANS partial geometry simulations (computationally least expensive) with a RNG k-ε turbulent model and one cycle or more are good enough for capturing overall qualitative flow trends for the engineering applications. However, if one is interested in getting reasonably accurate estimates of velocity magnitudes, flow structures, turbulence magnitudes, and its distribution, they must resort to LES simulations. Furthermore, to get the most accurate turbulence distributions, one must consider running LES full geometry simulations.

Fluid Flow Structure in Arterial Bypass Anastomosis

2005 ◽  
Vol 127 (4) ◽  
pp. 611-618 ◽  
Author(s):  
C. M. Su ◽  
D. Lee ◽  
R. Tran-Son-Tay ◽  
W. Shyy
Keyword(s):  
Fluid Flow ◽  
Flow Structure ◽  
Bypass Graft ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Arterial Bypass ◽  
Flow Recirculation ◽  
Area Reduction ◽  
Complex Flow Structure

The fluid flow through a stenosed artery and its bypass graft in an anastomosis can substantially influence the outcome of bypass surgery. To help improve our understanding of this and related issues, the steady Navier-Stokes flows are computed in an idealized arterial bypass system with partially occluded host artery. Both the residual flow issued from the stenosis—which is potentially important at an earlier stage after grafting—and the complex flow structure induced by the bypass graft are investigated. Seven geometric models, including symmetric and asymmetric stenoses in the host artery, and two major aspects of the bypass system, namely, the effects of area reduction and stenosis asymmetry, are considered. By analyzing the flow characteristics in these configurations, it is found that (1) substantial area reduction leads to flow recirculation in both upstream and downstream of the stenosis and in the host artery near the toe, while diminishes the recirculation zone in the bypass graft near the bifurcation junction, (2) the asymmetry and position of the stenosis can affect the location and size of these recirculation zones, and (3) the curvature of the bypass graft can modify the fluid flow structure in the entire bypass system.

scholarly journals Study of an array of two circular jets impinging on a flat surface

2018 ◽  
Vol 32 ◽  
pp. 01021
Author(s):  
Ştefan-Mugur Simionescu ◽  
Nilesh Dhondoo ◽  
Corneliu Bălan
Keyword(s):  
High Speed ◽  
Solid Wall ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Vortical Structures ◽  
Air Jets ◽  
Circular Jets ◽  
2D Flow ◽  
Rans Modeling ◽  
Two Jets

In this study, the flow characteristics of an array of two circular, laminar air jets impinging on a smooth solid wall are experimentally and numerically investigated. Direct visualizations using high speed/resolution camera are performed. The evolution of the vortical structures in the area where the jet is deflected from axial to radial direction is emphasized, as well as the interaction between the two jets. A set of CFD numerical simulations in 2D flow domains are performed by using the commercial software Fluent, in the context of Reynolds-averaged Navier-Stokes (RANS) modeling. The numerical resultsare compared and validated with the experiments. The vorticity number is computed and plotted at two different positions from the jet nozzle, and a study of its distribution gives a clue on how the jets are interacting with each other in the proximity of the solid wall.

Sign in / Sign up

Export Citation Format

Share Document