scholarly journals Retrofitting a high-speed marine engine to dual-fuel methanol-diesel operation: A comparison of multiple and single point methanol port injection

2021 ◽  
Vol 7 ◽  
pp. 100010
Author(s):  
Jeroen Dierickx ◽  
Jip Verbiest ◽  
Tom Janvier ◽  
Jens Peeters ◽  
Louis Sileghem ◽  
...  
Keyword(s):  
High Speed ◽  
Single Point ◽  
Dual Fuel ◽  
Marine Engine ◽  
Diesel Operation

scholarly journals A Numerical Study on the Combustion Process and Emission Characteristics of a Natural Gas-Diesel Dual-Fuel Marine Engine at Full Load

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1342
Author(s):  
Van Chien Pham ◽  
Jae-Hyuk Choi ◽  
Beom-Seok Rho ◽  
Jun-Soo Kim ◽  
Kyunam Park ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Simulation Software ◽  
Dual Fuel ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Cylinder Pressure ◽  
Marine Engine ◽  
Full Load ◽  
Simulation Results

This paper presents research on the combustion and emission characteristics of a four-stroke Natural gas–Diesel dual-fuel marine engine at full load. The AVL FIRE R2018a (AVL List GmbH, Graz, Austria) simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both diesel and dual-fuel mode to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed a good agreement with the measured values reported in the engine’s shop test technical data. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 1.7% and 6.75%, while NO, soot, CO, and CO2 emissions were reduced up to 96%, 96%, 86%, and 15.9%, respectively, in the dual-fuel mode in comparison with the diesel mode. The results also show better and more uniform combustion at the late stage of the combustions inside the cylinder when operating the engine in the dual-fuel mode. Analyzing the emission characteristics and the engine performance when the injection timing varies shows that, operating the engine in the dual-fuel mode with an injection timing of 12 crank angle degrees before the top dead center is the best solution to reduce emissions while keeping the optimal engine power.

On the high-speed Single Point Incremental Forming of titanium alloys

CIRP Annals ◽  
2013 ◽  
Vol 62 (1) ◽  
pp. 243-246 ◽  
Author(s):  
G. Ambrogio ◽  
F. Gagliardi ◽  
S. Bruschi ◽  
L. Filice
Keyword(s):  
Titanium Alloys ◽  
High Speed ◽  
Incremental Forming ◽  
Single Point ◽  
Single Point Incremental Forming

Dieless Water Jet Incremental Micro-Forming

2018 ◽  
Author(s):  
Yi Shi ◽  
Jian Cao ◽  
Kornel F. Ehmann
Keyword(s):  
Process Parameters ◽  
Thin Shell ◽  
High Speed ◽  
Single Point ◽  
Sheet Thickness ◽  
Water Jet ◽  
Micro Forming ◽  
Forming Process ◽  
Thin Foils ◽  
High Pressure Water Jet

Compared to the conventional single-point incremental forming (SPIF) processes, water jet incremental micro-forming (WJIMF) utilizes a high-speed and high-pressure water jet as a tool instead of a rigid round-tipped tool to fabricate thin shell micro objects. Thin foils were incrementally formed with micro-scale water jets on a specially designed testbed. In this paper, the effects on the water jet incremental micro-forming process with respect to several key process parameters, including water jet pressure, relative water jet diameter, sheet thickness, and feed rate, were experimentally studied using stainless steel foils. Experimental results indicate that feature geometry, especially depth, can be controlled by adjusting the processes parameters. The presented results and conclusions provide a foundation for future modeling work and the selection of process parameters to achieve high quality thin shell micro products.

scholarly journals Optimal Falling Track Design for Twice detonating Fuze of Double event Fuel air Explosive with High Speed

2020 ◽  
Vol 70 (4) ◽  
pp. 366-373
Author(s):  
Congliang Ye ◽  
Qi Zhang
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Single Point ◽  
Design System ◽  
Motion Trajectory ◽  
Novel Approach ◽  
Scale Experiment ◽  
Set Up ◽  
Point Center ◽  
Double Event

To prevent the initiation failure caused by the uncontrolled fuze and improve the weapon reliability in the high-speed double-event fuel-air explosive (DEFAE) application, it is necessary to study the TDF motion trajectory and set up a twice-detonating fuze (TDF) design system. Hence, a novel approach of realising the fixed single-point center initiation by TDF within the fuel air cloud is proposed. Accordingly, a computational model for the TDF motion state with the nonlinear mechanics analysis is built due to the expensive and difficult full-scale experiment. Moreover, the TDF guidance design system is programmed using MATLAB with the equations of mechanical equilibrium. In addition, by this system, influences of various input parameters on the TDF motion trajectory are studied in detail singly. Conclusively, the result of a certain TDF example indicates that this paper provides an economical idea for the TDF design, and the developed graphical user interface of high-efficiency for the weapon designers to facilitate the high-speed DEFAE missile development.

scholarly journals Stability analysis for a single-point cutting tool deflection in turning operation

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985318
Author(s):  
Amon Gasagara ◽  
Wuyin Jin ◽  
Angelique Uwimbabazi
Keyword(s):  
Cutting Forces ◽  
High Speed ◽  
Cutting Tool ◽  
Single Point ◽  
Three Dimensional ◽  
High Speed Steel ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Beam Model ◽  
Tool Deflection

In this article, a new model of regenerative vibrations due to the deflection of the cutting tool in turning is proposed. The previous study reported chatter as a result of cutting a wavy surface of the previous cut. The proposed model takes into account cutting forces as the main factor of tool deflection. A cantilever beam model is used to establish a numerical model of the tool deflection. Three-dimensional finite element method is used to estimate the tool permissible deflection under the action of the cutting load. To analyze the system dynamic behavior, 1-degree-of-freedom model is used. MATLAB is used to compute the system time series from the initial value using fourth-order Runge–Kutta numerical integration. A straight hard turning with minimal fluid application experiment is used to obtain cutting forces under stable and chatter conditions. A single-point cutting tool made from high-speed steel is used for cutting. Experiment results showed that for the cutting parameters above 0.1mm/rev feed and [Formula: see text]mm depth of cut, the system develops fluctuations and higher chatter vibration frequency. Dynamic model vibration results showed that the cutting tool deflection induces chatter vibrations which transit from periodic, quasi-periodic, and chaotic type.

Size and morphology of soot produced by a dual-fuel marine engine

2019 ◽  
Vol 138 ◽  
pp. 105448 ◽  
Author(s):  
Una Trivanovic ◽  
Joel C. Corbin ◽  
Alberto Baldelli ◽  
Weihan Peng ◽  
Jiacheng Yang ◽  
...  
Keyword(s):  
Dual Fuel ◽  
Marine Engine ◽  
Size And Morphology

scholarly journals Ultra High Speed Grinding of the Glass with a Single Point Diamond.

1994 ◽  
Vol 60 (9) ◽  
pp. 1294-1298
Author(s):  
Masayuki TAKAHASHI ◽  
Shyuji UEDA ◽  
Toshiji KUROBE
Keyword(s):  
High Speed ◽  
Single Point ◽  
Ultra High Speed ◽  
High Speed Grinding

Ignition of Diesel Pilot Fuel in Dual-Fuel Engines

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Marcus Grochowina ◽  
Daniel Hertel ◽  
Simon Tartsch ◽  
Thomas Sattelmayer
Keyword(s):  
High Speed ◽  
Measurement Techniques ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Spray Formation ◽  
Fuel Concentration ◽  
Injection Parameters ◽  
Pilot Fuel ◽  
Ignition And Combustion

Dual-fuel (DF) engines offer great fuel flexibility combined with low emissions in gas mode. The main source of energy in this mode is provided by gaseous fuel, while the diesel fuel acts only as an ignition source. For this reason, the reliable autoignition of the pilot fuel is of utmost importance for combustion in DF engines. However, the autoignition of the pilot fuel suffers from low compression temperatures caused by Miller valve timings. These valve timings are applied to increase efficiency and reduce nitrogen oxide (NOx) emissions. Previous studies have investigated the influence of injection parameters and operating conditions on ignition and combustion in DF engines using a unique periodically chargeable combustion cell. Direct light high-speed images and pressure traces clearly revealed the effects of injection parameters and operating conditions on ignition and combustion. However, these measurement techniques are only capable of observing processes after ignition. In order to overcome this drawback, a high-speed shadowgraph technique was applied in this study to examine the processes prior to ignition. Measurements were conducted to investigate the influence of compression temperature and injection pressure on spray formation and ignition. Results showed that the autoignition of diesel pilot fuel strongly depends on the fuel concentration within the spray. The high-speed shadowgraph images revealed that in the case of very low fuel concentration within the pilot spray, only the first stage of the two-stage ignition occurs. This leads to large cycle-to-cycle variations and misfiring. However, it was found that a reduced number of injection holes counteract these effects. The comparison of a diesel injector with ten-holes and a modified injector with five-holes showed shorter ignition delays, more stable ignition and a higher number of ignited sprays on a percentage basis for the five-hole nozzle.

Weathervane Performance and Stability of Single Point Moored FOWTs Under Wind-Current Coexisting Field

2019 ◽  
Author(s):  
Sharath Srinivasamurthy ◽  
Kazuki Hashimoto ◽  
Kazuhiro Iijima ◽  
Yasunori Nihei
Keyword(s):  
High Speed ◽  
Single Point ◽  
Scaling Law ◽  
Water Tank ◽  
Scaled Model ◽  
Circulating Water ◽  
Osaka Prefecture ◽  
Unstable Oscillation ◽  
The Stability ◽  
Numerical Program

Abstract The objective of this study is to understand the weathervane performance and stability of FOWTs moored to SPM systems under wind and current coexisting field. Two types of FOWT systems, a semi-submersible and a spar (1/200 scale) are designed and manufactured based on Froude’s scaling law. A series of scaled model experiments are conducted and compared during wind-current coexisting field in a circulating water tank at Osaka Prefecture University, Osaka, Japan. Weathervane performance is evaluated under various conditions of wind and current. It is found during experiments that the weathervane performance of the SPM-FOWT systems is acceptable in rated wind and slow current condition. However, in the rated wind and high speed current condition, the weathervane performance is found to be not acceptable and unstable oscillation is observed. A numerical program is also developed to understand the behavior using the maneuvering equations. Further, attempts are made to understand the stability of SPM-FOWT systems based on Eigenvalue analysis.

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