scholarly journals Bottom Dead Center Sensor Bracket Device

2020 ◽  
Author(s):  
Keyword(s):  
Bottom Dead Center

scholarly journals Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 245
Author(s):  
Anja Fink ◽  
Oliver Nett ◽  
Simon Schmidt ◽  
Oliver Krüger ◽  
Thomas Ebert ◽  
...  
Keyword(s):  
Free Stream ◽  
Combustion Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Vertical Direction ◽  
Spray Angle ◽  
Transport Sector ◽  
Flow Measurements ◽  
Injection Process ◽  
Bottom Dead Center

The H2 internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H2 direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H2 operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H2 flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H2 free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H2 far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H2 free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.

scholarly journals A Model-Based Control Design Approach for Linear Free-Piston Engines

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
T. N. Kigezi ◽  
J. F. Dunne
Keyword(s):  
Control Design ◽  
Linear Quadratic Regulator ◽  
Design Approach ◽  
Linear Quadratic ◽  
Free Piston ◽  
Model Based Control ◽  
Model Based ◽  
Bottom Dead Center ◽  
Free Piston Engine ◽  
Advanced Control

A general design approach is presented for model-based control of piston position in a free-piston engine (FPE). The proposed approach controls either “bottom-dead-center” (BDC) or “top-dead-center” (TDC) position. The key advantage of the approach is that it facilitates controller parameter selection, by the way of deriving parameter combinations that yield both stable BDC and stable TDC. Driving the piston motion toward a target compression ratio is, therefore, achieved with sound engineering insight, consequently allowing repeatable engine cycles for steady power output. The adopted control design approach is based on linear control-oriented models derived from exploitation of energy conservation principles in a two-stroke engine cycle. Two controllers are developed: A proportional integral (PI) controller with an associated stability condition expressed in terms of controller parameters, and a linear quadratic regulator (LQR) to demonstrate a framework for advanced control design where needed. A detailed analysis is undertaken on two FPE case studies differing only by rebound device type, reporting simulation results for both PI and LQR control. The applicability of the proposed methodology to other common FPE configurations is examined to demonstrate its generality.

The Performance Simulation of One-Way Inlet Valve of Reflux Scavenging Free Piston Engine

2013 ◽  
Vol 694-697 ◽  
pp. 582-587
Author(s):  
Zhen Xin Li ◽  
Zhao Cheng Yuan ◽  
Jia Yi Ma ◽  
Shi Yu Li
Keyword(s):  
Flow Rate ◽  
Spring Constant ◽  
Air Flow Rate ◽  
Inlet Valve ◽  
Free Piston ◽  
Performance Simulation ◽  
Bottom Dead Center ◽  
Free Piston Engine ◽  
Opening And Closing ◽  
Stroke Engine

The performance of one-way inlet valve directly impacts the effect of the reflux scavenging two-stroke engine intake. It’s discovered that the intake air flow rate, the weight of valve and the spring constant have the greatest impact on the opening, closing and the lift change of one-way inlet valve, by simulating the movement of piston and valve using CFD software. The greater the flow rate, the smaller the weight of valve, or the smaller the spring constant, then the faster the opening of valve. Meanwhile, in order to ensure that the valve quickly returns, the bigger of spring constant is the better. The phases of opening and closing of valve lag fall behind the phases of piston getting to bottom dead center (BDC) and top dead center (TDC).

scholarly journals Study on the Dynamic Characteristics of a Hydraulic Continuous Variable Compression Ratio System

2019 ◽  
Vol 9 (21) ◽  
pp. 4484 ◽  
Author(s):  
Chen ◽  
Wang ◽  
Liu ◽  
Yang
Keyword(s):  
Dynamic Characteristics ◽  
Compression Ratio ◽  
Hydraulic System ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Fast Response ◽  
Continuous Variable ◽  
Variable Compression Ratio ◽  
Bottom Dead Center ◽  
Variable Compression

Variable compression ratio (VCR) technology has long been recognized as a method for improving the engine performance, efficiency, and fuel economy of automobiles, with reduced emissions. In this paper, a novel hydraulic continuous VCR system based on the principle of an adjustable hydraulic volume is introduced. The continuous variable compression ratio of the VCR system is realized by the hydraulic system controlling the rotation of the eccentric pin to change the positions of the top dead center (TDC) and the bottom dead center (BDC). The construction of the mathematical model and simulation model of the VCR system is also presented in this paper. The piston motion characteristics, flow characteristics, and pressure characteristics of the hydraulic system of the VCR system at different engine speeds and adjustment quantities are studied by simulation in this paper. The simulation results show that the VCR system has a fast response and good dynamic characteristics, and can achieve continuous adjustment of the compression ratio.

Novel Piston Pressure Carryover for Dynamic Analysis and Designs of the Axial Piston Pump

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Piston Pump ◽  
Axial Piston Pump ◽  
Pump Performance ◽  
Axial Piston Pumps ◽  
Bottom Dead Center ◽  
Pump Pressure ◽  
Definition Of ◽  
And Control ◽  
Axial Piston ◽  
The Relationship

The timing definition of valve plates is one of the most complex topics in the piston pump designs because it affects many pump characteristics (such as efficiency, swashplate stroking, stabilities, noise, etc.). In the study, the pressure carryover is introduced and defined as the average angular positions to locate piston pressure transitions from the top dead center (TDC) or bottom dead center (BDC) in the piston pump. Pressure carryover presents the overall outcome of the pressure transitions within piston bores. The new pressure carryover definition is derived by the timing angles and other geometrics of valve plates that is an approximation of the practical pressure transitions. The pressure carryover also determines the containment forces and moments on the swashplate produced by the pumping pistons. The relationship between the pressure carryover angle and the containment moment has been developed and analyzed in the study. The amplitudes and frequencies of the forces and moments can be changed by varying the pressure carryover angle that produce different tonalities and control efforts for the swashplate type axial-piston pumps. Therefore, the pressure carryover is the most important and straightforward connection between pump dynamics and valve plate designs. In order to optimize the pump performance, the piston pressure carryover might be investigated thoroughly for the pump and its controller designs.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 3—Wear Assessment of Liner and Piston Rings, Engine Deposits, and Operational Issues

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Avinash Kumar Agarwal ◽  
Deepak Agarwal
Keyword(s):  
Piston Ring ◽  
Direct Injection ◽  
Cylinder Liner ◽  
Field Testing ◽  
Field Trials ◽  
Operating Conditions ◽  
Piston Rings ◽  
Carbon Deposits ◽  
Bottom Dead Center ◽  
Operational Issues

Abstract This study investigated the use of biodiesel (B100) and baseline mineral diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel’s compatibility and durability issues with modern common rail direct injection (CRDI) engine-powered vehicles. Two identical vehicles were operated for 30,000 km under identical operating conditions during a field-trial using biodiesel (B100) and mineral diesel. Exhaustive experimental results from this series of tests are divided into four sections, and this is the third paper of this series of four papers, which covers comparative feasibility and wear analyses, underlining the effect of long-term use of biodiesel on wear of cylinder liner and piston rings compared to baseline mineral diesel-fueled vehicle. Surface microstructures at three locations of the cylinder liner were evaluated using scanning electron microscopy (SEM). Wear was found to be relatively lower at all locations of liners from biodiesel-fueled vehicle compared to diesel-fueled vehicle. Surface roughness of cylinder liners measured at different locations showed that it reduced by ∼30–40% at top dead center (TDC), ∼10–20% at mid-stroke, and ∼20–30% at bottom dead center (BDC) for both vehicles, showing higher wear close to TDC compared to mid-stroke and BDC locations. Loss of piston-ring weight was significantly lower for biodiesel-fueled vehicle. Engine tear-down observations and carbon deposits on various engine components were recorded after the conclusion of the field trials. During these field-trials, engine durability-related issues such as fuel-filter plugging, injector coking, piston-ring sticking, carbon deposits in the combustion chamber, and contamination of lubricating oils were found to be relatively lower in biodiesel-fueled vehicle. Overall, no noticeable durability issues were recorded because of the use of biodiesel in CRDI engine-powered vehicle.

Dynamic precision analysis and experimental verification of high-speed precision punch press

2016 ◽  
Vol 230 (20) ◽  
pp. 3655-3662 ◽  
Author(s):  
Fengfeng Hu ◽  
Yu Sun ◽  
Binbin Peng
Keyword(s):  
Elastic Wave ◽  
Dynamic Model ◽  
High Speed ◽  
Impact Factors ◽  
Superposition Method ◽  
Bottom Dead Center ◽  
Dynamic Precision ◽  
Modal Superposition Method ◽  
The Impact ◽  
Punch Press

In order to investigate the impact factors and their affection on high-speed precision multilink punch press (MPP), the dynamic model with different joint clearance was established, and the influence of different clearance and speed on the dynamic positional repeatability of bottom dead center (BDC) was analyzed. The elastic dynamic model of high-speed MPP was established, the affection of the elastic deformation and elastic wave on the positional repeatability of the BDC were presented by using modal superposition method to solve dynamic equation. Meanwhile, experiments on the dynamic repeatability of the BDC of the punch during working were completed. At last, the comparison of the experimental results with the analyzed results was given, and based on which, it can be concluded that the clearance, elastic wave and deformation are the key factors of the dynamic repeatability precision of the BDC.

Piston Ring Cavitation and Starvation During Entrainment Motion Reversal

2010 ◽  
Author(s):  
W. W. F. Chong ◽  
M. Teodorescu ◽  
N. D. Vaughan
Keyword(s):  
Thin Films ◽  
Piston Ring ◽  
Film Formation ◽  
Leading Edge ◽  
Current Paper ◽  
Ic Engine ◽  
Entrainment Velocity ◽  
Bottom Dead Center ◽  
Engine Piston ◽  
Piston Ring Lubrication

The current paper investigates the correlation between oil film formation, cavitation and starvation during inlet reversal of an Internal Combustion (IC) engine piston-ring conjunction. Piston ring lubrication is critical in the vicinity of Top Dead Center (TDC) and Bottom Dead Center (BDC) where low entrainment velocity leads to very thin films. The current study predicts that cavities formed at the trailing edge of the contact before the entrainment reversal briefly survive at the leading edge after the reversal. This contributes to contact starvation and thinner films than previously thought.

PENGARUH INTAKE DAN EXHAUST LOBE LIFT SERTA CELAH KATUP TERHADAP KONSUMSI BAHAN BAKAR

2020 ◽  
Vol 1 (2) ◽  
pp. 44-49
Author(s):  
Musa Wahyu Pangeran
Keyword(s):  
Fuel Consumption ◽  
Research Method ◽  
Fossil Fuels ◽  
Positive Impact ◽  
Experimental Methods ◽  
Fuel Use ◽  
Bottom Dead Center

Abstrak: Sepeda motor membutuhkan bahan bakar fosil dan saat ini cadangannya semakin berkurang serta tidak dapat diperbarui. Dengan kondisi saat ini, perlu untuk mengontrol penggunaan bahan bakar pada sepeda motor. Pengaturan intake lobe lift, exhaust lobe lift dan celah katup berdampak positif pada konsumsi bahan bakar. Tujuan dari penelitian ini adalah untuk menguji pengaruh pengaturan intake lobe lift, exhaust lobe lift dan celah katup terhadap konsumsi bahan bakar pada sepeda motor Honda Supra 125. Metode penelitian menggunakan metode eksperimental. Hasil penelitian menunjukkan bahwa ada pengaruh variasi intake lobe lift, exhaust lobe lift dan celah katup terhadap konsumsi bahan bakar. Konsumsi bahan bakar terlama (irit) yaitu pada modifikasi camshaft intake lobe lift 250 sebelum Titik Mati Atas (TMA) dan exhaust lobe lift 450 setelah Titik Mati Bawah (TMB), celah katup masuk (in) adalah 0,15 mm dan keluar (ex) adalah 0,15 mm.   Abstract: Motorcycles need fossil fuels and currently reserves were decreasing and cannot be renewed. Under current conditions, it is necessary to control fuel use on motorbikes. The intake lobe lift, exhaust lobe lift and valve gap settings have a positive impact on fuel consumption. The purpose of this study was to examine the effect of regulating intake lobe lifts, exhaust lobe lifts and valve fissures on fuel consumption on Honda Supra 125 motorcycles. The research method used experimental methods. The results showed that there was an effect of variations in intake lobe lift, exhaust lobe lift and valve gap on fuel consumption. Economical fuel consumption is the modification of the intake lobe lift camshaft 250 before Top Dead Center (TDC) and exhaust lobe lift 450 after Bottom Dead Center (BDC), valve gap in 0.15 mm and ex 0.15 mm.

Simulation of Scavenging Process in a Two-Stroke Gasoline Engine

2012 ◽  
Vol 614-615 ◽  
pp. 376-380
Author(s):  
Chang Yuan Li ◽  
Dong Tang ◽  
Nan Li
Keyword(s):  
Flow Field ◽  
Gasoline Engine ◽  
Field Structure ◽  
Intake Port ◽  
Exhaust Gas ◽  
Three Dimension ◽  
Toroidal Vortex ◽  
Bottom Dead Center ◽  
Transient Numerical Simulation ◽  
Fresh Charge

Three-dimension transient numerical simulation of flow field in the transfer ports , exhaust port, intake port, crankcase and cylinder system of two-stroke gasoline engine was studied by using CFD software Fire, and the situations of airflow movement and exhaust gas distribution were presented dynamically in the scavenging process. The results show that flow field structure of the upper cylinder is mainly comprised of a pair of toroidal vortex and tumble vortex, while flow field structure of the lower cylinder is mainly comprised of four radial swirls and "short-circuiting" fuel losses. Along with the progress of scavenging process, the area of fresh charge and mixture increase while the exhaust gas area decreases accordingly. When the piston reaches to the BDC (bottom dead center), the exhaust gas area almost disappears.

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