Improvement of Poppet Valve Injection Performance in Large-Bore Natural Gas Engines

2004 ◽  
Author(s):  
Gi-Heon Kim ◽  
Allan Kirkpatrick ◽  
Charles Mitchell
Keyword(s):  
Natural Gas ◽  
Pressure Loss ◽  
Internal Combustion Engines ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Stagnation Pressure ◽  
Natural Gas Engines ◽  
Poppet Valve ◽  
Flow Through ◽  
Poppet Valves

Poppet valves have been used as fuel delivery mechanisms in internal combustion engines due to their excellent sealing characteristics. For example, in large-bore stationary natural gas engines, gas is directly injected by a poppet valve into the engine cylinder. The objectives of this paper are to show that a significant amount of stagnation pressure is lost during the gas flow through a conventional poppet valve and to suggest design improvements to obtain more efficient poppet valves with reduced stagnation pressure loss. In this paper, simple converging-diverging nozzles are incorporated into the poppet valve configuration to reduce the stagnation pressure loss originating from compressible flow structures. Numerical simulations of the gas flow through various poppet valve geometries were performed. Both push and pull poppet valve geometries with nozzle were studied. The stagnation pressure losses, momentum delivery downstream and downstream flow characteristics of the jets from conventional poppet valves and the modified valves were compared. A pressure-based valve injection efficiency was defined and used to compare the valve injection performance. A mixing fraction parameter was also defined to compare valve performance in a moving piston simulation. The results indicate that a conventional poppet valve is an inefficient mechanism to deliver momentum to the fuel-air mixture. Comparison of the results indicates that it is possible to make significant improvements of injection performance in momentum delivery by incorporating well-designed nozzles into the poppet valve geometry.

Paper 3: Steady Flow Tests on Twin Poppet Valves

1967 ◽  
Vol 182 (4) ◽  
pp. 126-133 ◽  
Author(s):  
W. A. Woods
Keyword(s):  
Steady Flow ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Effective Area ◽  
Valve Lift ◽  
Cylinder Wall ◽  
Large Area ◽  
Pressure Losses ◽  
Flow Through ◽  
Poppet Valves

This paper presents the results of an experimental investigation of steady flow through a pair of exhaust poppet valves. An account is given of the gas exchange process on engines which use poppet valves and the reason why pressure losses should be kept to a minimum is explained. Tests carried out on the cylinder head of a uniflow two-stroke cycle engine are described following a brief description of the apparatus used. The results of a simple analysis of incompressible flow are also given. It is shown that the two previous models of flow through a valve, namely the sudden enlargement and constant static pressure, both give unrealistic pressure losses for large area ratios, i.e. at high valve lifts. A new model is introduced which leads to realistic pressure losses at small and large area ratios, i.e. at low and high valve lifts. Effective areas for the present tests are calculated on the basis of the constant pressure model, and details of calculation of pressure losses are outlined. The blockage effect caused by placing the exhaust valves near the cylinder wall is given in the discussion of the test results. This is zero for 0 < l/d < 0·08, but reaches a maximum blockage of 10 per cent at l/d = 0·28. With unrestricted twin valves the effective area is about twice that of a single valve up to l/d = 0·18 with a progressively larger effective area at lifts up to 13 per cent higher at l/d = 0·4. A comparison is also made with other data readily available. The pressure losses determined from the tests were analysed using a parameter derived in the simple theory. The parameter used is found to be almost independent of pressure ratio and the results are presented by means of this pressure loss parameter as a function of valve lift. The representation provides a quantitative method of comparing the performance of a given configuration of valve and port. On this basis the twin poppet valves are shown to give a slightly higher pressure loss than a single valve.

Investigation of hydrate formation in natural gas flow through underground transmission pipeline

2013 ◽  
Vol 15 ◽  
pp. 27-37 ◽  
Author(s):  
Mahmood Farzaneh-Gord ◽  
Hamid Reza Rahbari ◽  
Mahdi Bajelan ◽  
Lila Pilehvari
Keyword(s):  
Natural Gas ◽  
Gas Flow ◽  
Hydrate Formation ◽  
Transmission Pipeline ◽  
Flow Through ◽  
Natural Gas Flow

The Influence of Different Rim Seal Geometries on Hot-Gas Ingestion and Total Pressure Loss in a Low-Pressure Turbine

2010 ◽  
Author(s):  
P. Schuler ◽  
W. Kurz ◽  
K. Dullenkopf ◽  
H.-J. Bauer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Gas Flow ◽  
Low Pressure ◽  
Total Pressure Loss ◽  
Pressure Loss Coefficient ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Flow Through ◽  
Total Pressure Loss Coefficient

In order to prevent hot-gas ingestion into the rotating turbo machine’s inside, rim seals are used in the cavities located between stator- and rotor-disc. The sealing flow ejected through the rim seal interacts with the boundary layer of the main gas flow, thus playing a significant role in the formation of secondary flows which are a major contributor to aerodynamic losses in turbine passages. Investigations performed in the EU project MAGPI concentrate on the interaction between the sealing flow and the main gas flow and in particular on the influence of different rim seal geometries regarding the loss-mechanism in a low-pressure turbine passage. Within the CFD work reported in this paper static simulations of one typical low-pressure turbine passage were conducted containing two different rim seal geometries, respectively. The sealing flow through the rim seal had an azimuthal velocity component and its rate has been varied between 0–1% of the main gas flow. The modular design of the computational domain provided the easy exchange of the rim seal geometry without remeshing the main gas flow. This allowed assessing the appearing effects only to the change of rim seal geometry. The results of this work agree with well-known secondary flow phenomena inside a turbine passage and reveal the impact of the different rim seal geometries on hot-gas ingestion and aerodynamic losses quantified by a total pressure loss coefficient along the turbine blade. While the simple axial gap geometry suffers considerable hot-gas ingestion upstream the blade leading edge, the compound geometry implying an axial overlapping presents a more promising prevention against hot-gas ingestion. Furthermore, the effect of rim seals on the turbine passage flow field has been identified applying adequate flow visualisation techniques. As a result of the favourable conduction of sealing flow through the compound geometry, the boundary layer is less lifted by the ejected sealing flow, thus resulting in a comparatively reduced total pressure loss coefficient over the turbine blade.

Phenomenological Modeling of Combustion in Pre-Chamber and the Pilot Flame for Natural Gas Engines

2019 ◽  
Author(s):  
Long Liu ◽  
Xia Wen ◽  
Qian Xiong ◽  
Xiuzhen Ma
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Alternative Fuels ◽  
Gas Flow ◽  
Combustion Process ◽  
Clean Energy ◽  
Combustion Model ◽  
Flame Surface ◽  
Flow Process ◽  
Natural Gas Engines

Abstract With energy shortages and increasing environmental problems, natural gas, as a clean energy, has the advantages of cheap price and large reserves and has become one of the main alternative fuels for marine diesel engines. For large bore natural gas engines, pre-chamber spark plug ignition can be used to increase engine efficiency. The engine mainly relies on the flame ejected from the pre-chamber to ignite the mixture of natural gas and air in the main combustion chamber. The ignition flame in the main combustion chamber is the main factor affecting the combustion process. Although the pre-chamber natural gas engines have been extensively studied, the characteristics of combustion in the pre-chamber and the development of ignition flame in the main combustion chamber have not been fully understood. In this study, a two-zone phenomenological combustion model of pre-chamber spark-ignition natural gas engines is established based on the exchange of mass and energy of the gas flow process in the pre-chamber and the main combustion chamber. The basic characteristics of the developed model are: a spherical flame surface is used to describe the combustion state in the pre-chamber, and according to the turbulent jet theory, the influence of turbulence on the state of the pilot flame is considered based on the Reynolds number. According to the phenomenological model, the time when the flame starts to be injected from the pre-chamber to the main combustion chamber, and the parameters such as the length of the pilot flame are analyzed. The model was verified by experimental data, and the results showed that the calculated values were in good agreement with the experimental values. It provides an effective tool for mastering the law of flame development and supporting the optimization of combustion efficiency.

The Flow Characteristics Analysis of Transonic around Delta-Wing to Separate Water from Natural Gas

2012 ◽  
Vol 462 ◽  
pp. 26-32
Author(s):  
Jun Qi Wang ◽  
Yang Yang Zhang
Keyword(s):  
Natural Gas ◽  
Gas Flow ◽  
Delta Wing ◽  
Temperature Drop ◽  
Flow Characteristics ◽  
Attack Angle ◽  
Water Separation ◽  
Process Gas ◽  
Characteristics Analysis ◽  
Expansion Angle

The changes in flow channel area and convergence-expanding nozzle help to flow rate of natural gas to the sound speed, also increase diameter to accelerate flow velocity and finally reach transonic flow condition. At this point, the temperature drop makes saturated water in natural gas condenses into droplets, generates swirl around the delta-wing, realize gas-water separation. This paper concentrates on Flent6.1 software process gas flow around a delta wing simulation, explains expansion angle and attack angle of delta-wing, determines a reasonable delta-wing attack angle is 10°, pipeline expansion angle is 0.29°, and obtains velocity vector, mach number, total pressure, static temperature and other flow field details of the attack angle and expansion angle, which lay foundation for production and application of the technology.

Prediction of natural gas flow through chokes using support vector machine algorithm

2014 ◽  
Vol 18 ◽  
pp. 155-163 ◽  
Author(s):  
Ibrahim Nejatian ◽  
Mojtaba Kanani ◽  
Milad Arabloo ◽  
Alireza Bahadori ◽  
Sohrab Zendehboudi
Keyword(s):  
Support Vector Machine ◽  
Natural Gas ◽  
Gas Flow ◽  
Support Vector ◽  
Support Vector Machine Algorithm ◽  
Flow Through ◽  
Natural Gas Flow

Non-Steady Flow through a Gauze in a Duct

1965 ◽  
Vol 7 (4) ◽  
pp. 449-459 ◽  
Author(s):  
R. S. Benson ◽  
P. C. Baruah
Keyword(s):  
Steady Flow ◽  
Excellent Agreement ◽  
Pressure Loss ◽  
Internal Combustion Engines ◽  
Wave Action ◽  
Combustion Engines ◽  
Flow Through ◽  
Flow Pressure ◽  
Loss Coefficients ◽  
Flow Experiments

By using steady flow relations including pressure loss coefficients a method is developed for calculating wave action in a duct with a gauze. Both steady and non-steady flow experiments for five gauzes are described. The results of the non-steady flow tests showed excellent agreement between the predicted indicator diagrams, using the steady flow pressure loss coefficients, and the measured indicator diagrams. The methods described in the paper may be used by engine designers to predict the effect of gauzes or similar devices on the wave action in exhaust systems of internal combustion engines.

Measurements of Blowdown Thrust Loading in Natural Gas Facilities

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
K. K. Botros ◽  
H. Charette ◽  
M. Martens ◽  
M. Beckel ◽  
G. Szuch
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Compressible Flow ◽  
Gas Flow ◽  
Flow Model ◽  
Stagnation Pressure ◽  
Flow Meters ◽  
One Dimensional ◽  
Pressure Losses ◽  
Modeling Approach

Abstract The thrust loading on a vertical blowdown stack during a natural gas blowdown was investigated using a combined experimental and modeling approach. A gravimetric vessel initially at 4000 kPa-g was blown down through two geometrically different stack assemblies. Thrust loads were measured using a dynamic weigh scale typically used for gravimetric calibration of gas flow meters. A one-dimensional (1D) compressible flow model, calibrated using the experimental data, revealed stagnation pressure losses at the entrance to the riser, resulting in lower thrust loads. A comparison between thrust loading obtained from the measurements and the 1D compressible flow model is presented. This work shows that the analytical flow model predicts the blowdown thrust loads within ±30%.

Effect of Casing Geometry on Flow Characteristics in a Model Can-Combustor

2012 ◽  
Author(s):  
Abdur Rahim ◽  
Dhirgham Alkhafagiy ◽  
Prabal Talukdar
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Total Pressure Loss ◽  
Stable Operation ◽  
Flow Uniformity ◽  
Flow Through ◽  
Combustor Liner

In a gas turbine combustor, it is necessary to use a diffuser to decelerate the high velocity air stream delivered by the compressor and thus avoid high total pressure loss. The interaction between the diffuser and combustor external flows plays a key role in controlling the pressure loss, air flow distribution around the combustor liner. Flow through casing-liner annulus is crucial as it feeds air to the primary, secondary and dilution holes. It is important that the annulus flow has sufficient static pressure to achieve adequate penetration of the jets. Moreover, the correct proportion of air enters the combustor liner through the dome and the various ports to maintain stable operation and good quality outlet condition. Length of combustor can be reduced if a provision is made for sufficient diffusion in the dump region. In the present numerical study, three can-combustor models of different geometry with a constant dump-gap have been analyzed with emphasis on the flow through annulus. A comparison has been made amongst the three models in terms of flow uniformity, static pressure recovery and total pressure loss. It is observed that flow uniformity in the annulus region is improved if a small divergence in length and a curved shape step height casing is made.

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