Valve and In-Cylinder Flow Generated by a Helical Port in a Production Diesel Engine

1987 ◽  
Vol 109 (4) ◽  
pp. 368-375 ◽  
Author(s):  
C. Arcoumanis ◽  
C. Vafidis ◽  
J. H. Whitelaw
Keyword(s):  
Diesel Engine ◽  
Laser Doppler Anemometry ◽  
Operating Conditions ◽  
Valve Lift ◽  
Valve Closure ◽  
Rapid Decay ◽  
Inlet Valve ◽  
Compression Stroke ◽  
Axial Velocity Distribution ◽  
Cylinder Flow

The flow generated by the helical port of a production Diesel engine has been investigated by laser Doppler anemometry under steady flow and operating conditions at ∼ 900 rpm and compression ratio of 8. The flow around the valve periphery was found to be non-uniform with the axial velocity distribution being more sensitive to valve lift. The in-cylinder swirl distribution at inlet valve closure exhibited an axial stratification in the disc-chamber while turbulence intensity remained constant in the clearance volume during the rest of the compression stroke with levels of 0.5 vp and a minimum of about 0.4 vp at top-dead-center following a rapid decay at θ=340°.

Study of the steady flow produced by direct injection diesel engine intake ports

2001 ◽  
Vol 215 (2) ◽  
pp. 285-298 ◽  
Author(s):  
J M Desantes ◽  
J V Pastor ◽  
A Doudou
Keyword(s):  
Spectral Analysis ◽  
Diesel Engine ◽  
Flow Field ◽  
Steady Flow ◽  
Cylinder Head ◽  
Laser Doppler Anemometry ◽  
Direct Injection ◽  
Valve Lift ◽  
Turbulent Structures ◽  
Direct Injection Diesel Engine

In this paper laser Doppler anemometry is used to characterize the steady flow field inside the cylinder generated by the two intake ports of a four-valve diesel head over the whole valve lift range and to compare the patterns at two different sections commonly used for global characterization in order to decide which is more appropriate for cylinder head evaluation. A more detailed investigation is performed for two valve lifts where the change in the flow patterns is more evident by applying a spectral analysis with the local normalized slotting technique to study the turbulent structures accompanying the in-cylinder swirl development.

Experiences With Simulation of Reciprocating Compressor Valve Dynamics

1996 ◽  
Author(s):  
Brian Howes ◽  
Leonard Lin ◽  
Val Zacharias
Keyword(s):  
Gas Flow ◽  
Economic Effect ◽  
Operating Conditions ◽  
Valve Lift ◽  
Reciprocating Compressor ◽  
Compression Process ◽  
Flow Area ◽  
Valve Dynamics ◽  
Compressor Performance ◽  
Cylinder Flow

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

Some Aspects of Combustion and Heat Release in Diesel Engines

1977 ◽  
Author(s):  
K.S. Kannan
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Digital Computer ◽  
Valve Closure ◽  
Inlet Valve ◽  
First Law Of Thermodynamics ◽  
Valve Opening ◽  
The University ◽  
University Of Manchester ◽  
Heat Released

The author discusses the various stages of combustion in diesel engines from experiments conducted by himself and also by various other research workers in this field. He then outlines the technique used in predicting heat released by the fuel during combustion in a diesel engine - a techniq ue on which he has worked during his Master's course at the University of Manchester Institute of Science and Technology. The technique consists of applying the first Law of Thermodynamics in steps of the period from inlet valve closure to exhaust valve opening. The First Law equation applicable is reformulated so as to be used on the digital computer.

Intake Valve and In-Cylinder Flow Development in a Reciprocating Model Engine

1986 ◽  
Vol 200 (2) ◽  
pp. 143-152 ◽  
Author(s):  
C Vafidis ◽  
J H Whitelaw
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Axial Flow ◽  
Normal Stresses ◽  
Intake Valve ◽  
Inlet Valve ◽  
Piston Bowl ◽  
Flow Development ◽  
Model Engine ◽  
Cylinder Flow

Measurements of three velocity components have been obtained by laser Doppler anemometry at the exit plane of the intake valve and inside the cylinder of a model engine motored at 200 r/min with a compression ratio of 7.7 and both axisymmetric and off-centre valves with flat and bowl-in-piston configurations. The results indicate that during early intake the valve flow is influenced by piston geometry and its proximity to the cylinder head. With the flat piston the TDC flow field is influenced by the intake-generated axial flow pattern but not by the tangential motion, induced by the off-centre valve, which decays around inlet valve closure. The breakdown of the intake-generated vortices is accompanied by redistribution of the normal stresses which, during compression, tend towards homogeneity. Inside the piston bowl, a vortex is induced during early intake and decays later in the induction stroke to a uniform flow field which is transformed during late compression by the squish effect.

Intake Turbulence Generated by a Steady Valve-Cylinder Flow

2002 ◽  
Author(s):  
Gearle Bailey ◽  
John Kuhlman
Keyword(s):  
Laser Doppler Anemometry ◽  
Axisymmetric Flow ◽  
Valve Lift ◽  
Intake Port ◽  
Intake Valve ◽  
Toroidal Vortex ◽  
Velocity Measurements ◽  
Mean Velocity ◽  
Cylinder Flow ◽  
Turbulence Generation

Axial and swirl velocities have been measured for steady axisymmetric flow in a cylinder past a fixed intake valve located on the cylinder centerline, for two different intake port geometries and two valve lifts, in order to study the effects of swirl and valve lift on turbulence generation. Both Laser Doppler Anemometry (LDA) and Constant Temperature Anemometry (CTA) velocity measurements were obtained. The cylinder diameter was 82.6 mm, cylinder height was 114.3 mm, and the centrally located valve had a diameter of 41.9 mm. The LDA mean axial velocity data indicated a conical jet issuing from the valve, and a recirculating toroidal vortex above the valve for each case. Also, for the swirl intake cases, the swirl mean velocity in the toroidal vortex increased linearly with radius. Axial fluctuation velocities were about 1 m/sec away from the conical jet, for both valve lifts and both inlet flow geometries. In the conical jet, axial fluctuation velocities of 2–2.5 m/sec were observed. The swirl fluctuation was consistently lower than the axial fluctuation. The swirl inlet increased the magnitude of the swirl fluctuation in the conical jet.

Measurements in a Motored Four-Stroke Reciprocating Model Engine

1982 ◽  
Vol 104 (2) ◽  
pp. 235-241 ◽  
Author(s):  
C. Arcoumanis ◽  
A. F. Bicen ◽  
J. H. Whitelaw
Keyword(s):  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Swirl Flow ◽  
Inlet Valve ◽  
Piston Bowl ◽  
Compression Stroke ◽  
Piston Head ◽  
The Mean ◽  
Model Engine ◽  
Comparison Of The Results

Measurements of ensemble-averaged axial and swirl velocities and the rms of the corresponding fluctuations obtained by laser-Doppler anemometry, are reported for the axisymmetric swirling flow in a four-stroke model engine motored at 200 rpm with a compression ratio of 3.5. A centrally located valve, incorporating a 60 degree seat angle and 30 degree swirl vanes resulting in a swirl number of 1.2, was used to draw in and exhaust seeded air. The piston-head configurations included a flat surface and a cylindrical bowl with and without a lip. Comparison of the results with those obtained previously, with a flat piston in the absence of compression, shows that the mean and rms profiles during the intake stroke are similar. In the axial plane a system of vortices is created which has almost disappeared by the time the inlet valve closes with a small vortex existing near the cylinder head at the early part of compression; later on this vortex breaks up and the mean velocities tend to become uniform. The intake generated turbulence decays gradually until the inlet valve closes; it then becomes uniform and remains constant in magnitude for the rest of the compression stroke. The mean swirl flow has a spiralling nature during intake but tends towards solid body rotation during compression with associated turbulence levels of similar magnitude to the axial ones. During the expansion stroke the rms velocities decrease further until the exhaust valve opens and new turbulence is generated. The influence of the piston bowl is generally small but the addition of a lip results, during the compression stroke, in inward movement of the air towards the bowl as the piston approaches TDC. The reverse squish effect, observed during the expansion stroke and due to the outgoing motion of the entrapped air inside the bowl, results in significant reversed velocities near the axis and increase in the turbulence levels close to the piston.

Improving diesel engine efficiency at high speeds and loads through improved breathing via delayed intake valve closure timing

2017 ◽  
Vol 20 (2) ◽  
pp. 194-202 ◽  
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Xueting Lu ◽  
Cody M Allen ◽  
James McCarthy ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Effective Pressure ◽  
Intake Valve ◽  
Brake Mean Effective Pressure ◽  
Gas Recirculation

Valve train flexibility enables optimization of the cylinder-manifold gas exchange process across an engine’s torque/speed operating space. This study focuses on the diesel engine fuel economy improvements possible through delayed intake valve closure timing as a means to improve volumetric efficiency at elevated engine speeds via dynamic charging. It is experimentally and analytically demonstrated that intake valve modulation can be employed at high-speed (2200 r/min) and medium-to-high load conditions (12.7 and 7.6 bar brake mean effective pressure) to increase volumetric efficiency. The resulting increase in inducted charge enables higher exhaust gas recirculation fractions without penalizing the air-to-fuel ratio. Higher exhaust gas recirculation fractions allow efficiency improving injection advances without sacrificing NOx. Fuel savings of 1.2% and 1.9% are experimentally demonstrated at 2200 r/min for 12.7 and 7.6 bar brake mean effective pressure operating conditions via this combined strategy of delayed intake valve closure, higher exhaust gas recirculation fractions, and earlier injections.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

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