scholarly journals Optimal Design Parameters of a Percussive Drilling System for Efficiency Improvement

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Changheon Song ◽  
Jintai Chung ◽  
Jae-Sang Cho ◽  
Yun-Joo Nam
Keyword(s):  
Optimal Design ◽  
Resistance Coefficient ◽  
Rock Breaking ◽  
Performance Estimation ◽  
Design Parameters ◽  
Percussive Drilling ◽  
Rock Interaction ◽  
Breaking Mechanism ◽  
And Performance ◽  
The Impact

This paper aims to determine the optimal design parameters for percussive drilling systems considering the bit-rock interaction. First, the motion dynamics of a bit impacted by a dropped piston are modeled by impact stress propagation and a rock-breaking mechanism representing the penetration resistance coefficient and unloading constant. Next, the damping vibration behavior of the bit is investigated considering the impact duration and the rock loading/unloading condition. In addition, the proposed dynamics are simplified by adopting two dimensionless parameters representing the bit-piston mass ratio and the rock-piston stiffness ratio. Finally, the drilling efficiency, defined by the energy transmitted from the piston to the rock, is presented in terms of the proposed parameters. The use of optimal design parameters for percussive drilling systems improved the drilling efficiency. These results are applicable to the design and performance estimation of down-the-hole and top-hammer systems.

Study on Rock-Breaking Simulation and Experiment of Double Disc Cutter of TBM

2016 ◽  
Vol 23 ◽  
pp. 80-88
Author(s):  
F. Lu ◽  
C. Zhang ◽  
J. Sun ◽  
J.X. Tian ◽  
M. Liu ◽  
...  
Keyword(s):  
Rock Breaking ◽  
Disc Cutter ◽  
Element Analysis ◽  
Breaking Effect ◽  
The Finite Element Analysis ◽  
Breaking Mechanism ◽  
Simulation And Experiment ◽  
Tbm Cutter ◽  
Cutter Spacing ◽  
The Impact

In order to improve working efficiency of the tunneling process and extend working life of disc cutter, explore the impact of cutter spacing and loading for the cutter rock-breaking effect. With the theory of rock crushing, Based on the finite element analysis software ABAQUS, the process of disc cutter breaking rock is simulated, considering the adjacent cutters sequential constraints, then, to make sure two cutter space with the method of SE in experiment.The simulation results showed that the optimal cutter spacings were both about 80mm in the same loading and the sequentially loading, but the rock-breaking effect of sequentially loading is better than the same loading. The experimental data showed that the minimum specific energy of rock breaking is appeared cutter spacing between 80mm and 90mm. Thus, the correctness and rationality of the simulation was verified. The study is good for understanding the rock-breaking mechanism of double disc cutter and has a certain promoting value to optimize TBM cutter system.Keywords:TBM, rock fragmentation, ABAQUS, cutter spacing, sequentially cutting

Numerical Investigation of the Effect of Diffuser and Volute Design Parameters on the Performance of a Centrifugal Compressor Stage

2016 ◽  
Author(s):  
Lei Yu ◽  
William T. Cousins ◽  
Feng Shen ◽  
Georgi Kalitzin ◽  
Vishnu Sishtla ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Rise ◽  
Design Parameters ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Cross Sectional ◽  
Centrifugal Stage ◽  
And Performance ◽  
The Impact

In this effort, 3D CFD simulations are carried out for real gas flow in a refrigeration centrifugal compressor. Both commercial and the in-house CFD codes are used for steady and unsteady simulations, respectively. The impact on the compressor performance with various volute designs and diffuser modifications are investigated with steady simulations and the analysis is focused on both the diffuser and the volute loss, in addition to the flow distortion at impeller exit. The influence of the tongue, scroll diffusion ratio, diffuser length, and cross sectional area distribution is examined to determine the impact on size and performance. The comparisons of total pressure loss, static pressure recovery, through flow velocity, and the secondary flow patterns for different volute designs show that the performance of the centrifugal compressor depends upon how well the scroll portion of the volute collects the flow from the impeller and achieves the required pressure rise with minimum flow losses in the overall diffusion process. Finally, the best design is selected based on compressor stage pressure rise and peak efficiency improvement. An unsteady simulation of the full wheel compressor stage was carried out to further examine the interaction of impeller, diffuser and the volute. The unsteady flow interactions are shown to have a major impact on the performance of the centrifugal stage.

Drive modelling and performance estimation of IPM motor using SVPWM and Six-step Control Strategy

2021 ◽  
Keyword(s):  
Comprehensive Evaluation ◽  
Element Model ◽  
Torque Ripple ◽  
Performance Estimation ◽  
Smooth Transition ◽  
Motor Speed ◽  
Traction Motor ◽  
Modulation Techniques ◽  
And Performance ◽  
The Impact

This paper presents a comprehensive evaluation of the performance of an interior permanent magnet (IPM) traction motor drive, and analyses the impact of different modulation techniques. The most widely used modulation methods in traction motor drives are Space vector modulation (SVPWM), over-modulation, and six-step modulation have been implemented. A two-dimensional electromagnetic finite element model of the motor is co-simulated with a dynamic model of a field-oriented control (FOC) circuit. For accurate tuning of the current controllers, extended complex vector synchronous frame current regulators are employed. The DC-link voltage utilization, harmonics in the output waveforms, torque ripple, iron losses, and AC copper losses are calculated and compared with sinusoidal excitation. Overall, it is concluded that the selection of modulation technique is related to the operating condition and motor speed, and a smooth transition between different modulation techniques is essential to achieve a better performance.

Structure Analysis and Performance Simulation on the Walking Mechanism of the Transportation Machine Providing Disaster Relief

2011 ◽  
Vol 183-185 ◽  
pp. 2237-2241
Author(s):  
Hui Wang ◽  
Yan Ma ◽  
Chang Qing Ren ◽  
Ning Li
Keyword(s):  
Disaster Relief ◽  
Impact Factors ◽  
Design Parameters ◽  
Theoretical Derivation ◽  
Component Size ◽  
Development And Utilization ◽  
The New Period ◽  
And Performance ◽  
Walking Mechanism ◽  
The Impact

It makes a brief description of the transportation machine providing disaster relief. The paper makes a deep analysis and founds a scheme on the walking mechanism of the transportation machine sending relief to a disaster area, illustrates the relationship among the mechanism structure, component size, tracks and kinematic parameters of the foot. It makes an experimental prototype design which through the analysis before, embeds the scheme into the design parameters, and conducts an actual verification about the results of theoretical derivation. The results proved the feasibility of the design, and reflected the impact factors. It will lay the theoretical foundation for the walking mechanism’s design and research of the transportation machine providing disaster relief, and will be in favor of the development and utilization of the transportation machine providing disaster relief in the new period.

Active Torsion Bar Body Roll Minimization System: Design and Testing

2003 ◽  
Author(s):  
David Cimba ◽  
Kyle Gilbert ◽  
John Wagner
Keyword(s):  
Cost Effective ◽  
Vehicle Body ◽  
Design Parameters ◽  
Test Environment ◽  
Component Design ◽  
Body Roll ◽  
And Performance ◽  
Emergency Scenarios ◽  
The Impact ◽  
Torsion Bar

Sport utility and light-duty commercial vehicles exhibit a higher propensity for rollover during aggressive driving maneuvers, emergency scenarios, and degraded environmental conditions. A variety of strategies have been proposed to reduce vehicle body roll including active suspensions, comprehensive yaw stability systems, and active torsion bars. The active torsion bar systems have recently gained popularity due to their cost effective design and adaptability to existing chassis systems. However, the development of new control algorithms, design of subsystem components, and the evaluation of parameter sensitivity via testing a full scale vehicle is not always practical due to cost and safety concerns. Thus, a modular simulation tool and bench top testing environment is required to facilitate design and performance studies. In this paper, a series of mathematical models will be introduced to describe the vehicle dynamics and the roll prevention system. Representative numerical results are discussed to investigate a vehicle’s transient response with and without an active torsion bar system, as well as the impact of torsion bar and hydraulic component design parameters. Finally, a hardware in-the-loop test environment will be presented.

Selection of One-Dimensional Design Parameter ‘Reaction Degree’ for 1st Stage of a Cooled Gas Turbine

2012 ◽  
Author(s):  
Hina Noor ◽  
Magnus Genrup ◽  
Torsten Fransson
Keyword(s):  
Mass Flow ◽  
Design Parameter ◽  
Design Tool ◽  
Performance Estimation ◽  
Design Parameters ◽  
Flow Angle ◽  
One Dimensional ◽  
And Performance ◽  
Reaction Degree ◽  
Selection Of

The recommendations available today in open literature for the choice of design parameter such as flow coefficient, stage loading and reaction degree incorporates mainly the influence of aerodynamics loss on efficiency. However, it is difficult to find the recommendation relating the influence of not only the aerodynamics loss but also cooling mass flow and cooling losses on varying most influential design parameters. In this paper, preliminary design and performance guidelines are presented for a cooled turbine stage using the 1D design tool LUAXT. The intention is to provide recommendations on the selection of design parameters, mainly reaction degree, which is found to be highly influenced by not only the aerodynamics loss but also the cooling mass flow and cooling loss such as in 1st stage of a High Pressure Turbines (HPT). The One-Dimensional (1D) design methods used to perform this task are verified and validated against experimental test data. A comparison of different loss models has been performed to provide most accurate outcomes for certain tested ranges. Based on the outcomes of this study, ‘Craig & Cox’ loss model has been considered to perform subsequent investigations for HPT design and performance estimation while formulating a parametric study. From this study, the design recommendations for the selection of performance parameter reaction degree are developed for cooled turbines. The results shows that for a HPT 1st stage, the recommended reaction degree range of 0.20 to 0.37 seems to provide the optimum stage design when chosen for stage loading in between 1.40 to 1.80 along with the stator exit flow angle in range of 74° to 78°.

The Automobile Tension Bar Time-Varying Reliability Sensitivity Analysis

2014 ◽  
Vol 620 ◽  
pp. 143-147
Author(s):  
Shu Sen Liu ◽  
Bo Qiang Shi ◽  
Wen Yu Zhang ◽  
Xue Jie Fu ◽  
Yue Wei Wu
Keyword(s):  
Sensitivity Analysis ◽  
Optimal Design ◽  
Optimization Design ◽  
Design Parameters ◽  
Time Varying ◽  
Reliability Sensitivity ◽  
Reliability Sensitivity Analysis ◽  
Robust Optimal Design ◽  
Robust Optimization Design ◽  
The Impact

In this paper, the design of a automobile tension bar analysis example, the use of sensitivity analysis of time-varying reliability robust optimal design tension bar design parameters for reliability sensitivity analysis shows that the reliability of the impact of the strength of the material and rod diameter is positive, and the reliability of the impact of the load and rod diameter is negative. Correct application of time-varying reliability robust optimal design of mechanical parts when variant reliability robust optimization design, design service at any time during the period were not sensitive to changes of the design parameters of the reliability of the parts, and improve the parts reliability soundness.

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