Computational Investigation of the Effects of Piston Geometry on the Combustion Evolution in a Light Duty HSDI Engine

2017 ◽  
Author(s):  
Riyaz Ismail ◽  
Felix Leach ◽  
Martin H. Davy ◽  
David Richardson ◽  
Brian Cooper
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Adaptive Mesh Refinement ◽  
Fuel Injection ◽  
Temporal Distribution ◽  
Adaptive Mesh ◽  
Test Point ◽  
Piston Bowl ◽  
Dynamics Simulations

The spatial and temporal distribution of fuel and air within the combustion chamber directly influences ignition, combustion and emissions formation in diesel engines. These fuel-air interactions are affected by details of the combustion chamber geometry and fuel injection parameters. This paper investigates the effects of piston bowl geometry and spray targeting on combustion behaviour in a single cylinder diesel engine. Closed cycle computational fluid dynamics simulations are performed on a sector mesh at various load points using the 3 Zones Extended Coherent Flame Model coupled with adaptive mesh refinement. The computational fluid dynamics model is validated experimentally at the baseline conditions at each test point after-which, parametric sweeps of bowl geometry, exhaust gas recirculation rate and nozzle tip protrusion are conducted. Results indicate that appropriately pairing fuel injection strategy and piston geometry is essential.

scholarly journals A space-time parallel algorithm with adaptive mesh refinement for computational fluid dynamics

2020 ◽  
Vol 23 (1-4) ◽  
Author(s):  
Joshua Christopher ◽  
Robert D. Falgout ◽  
Jacob B. Schroder ◽  
Stephen M. Guzik ◽  
Xinfeng Gao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Parallel Algorithm ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Space Time

IN-CYLINDER FLOW ANALYSIS FOR A DIRECT INJECTION DIESEL ENGINE – A CFD APPROACH

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Ananthakumar S ◽  
Jayabal S ◽  
Thirumal P
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Direct Injection ◽  
Flow Analysis ◽  
Direct Injection Diesel Engine ◽  
Piston Bowl ◽  
Mexican Hat ◽  
Swirl Velocity

A parametric study of the effect of piston bowl configuration on air motion of a direct injection diesel engine motored at 3000 rpm is investigated. Two piston bowl configurations (Mexican-hat and Re-entrant) are modeled for the computational flow analysis. The flow characteristics of these engine bowls are examined under transient conditions using STAR CD, a commercial computational fluid dynamics package. The predicted computational fluid dynamics results of mean swirl velocity of the engine at different locations inside the combustion chamber, at the end of compression stroke were compared with experimental results available in the literature. The results obtained showed very good agreement with the measured data given in the literature. This paper discusses the predicted flow structure inside the combustion chamber at top dead center, with different piston bowl shapes at 3000 rpm. It also compares the radial distribution of mean swirl velocity component in the piston bowl for the two cases. It is observed that the Re-entrant bowl provides a higher swirl ratio at almost all locations than the Mexican hat bowl.

Computational fluid dynamics study of the effects of the re-entrant lip shape and toroidal radii of piston bowl on a high-speed direct-injection diesel engine's performance and emissions

2005 ◽  
Vol 219 (8) ◽  
pp. 1011-1023 ◽  
Author(s):  
Y Zhu ◽  
H Zhao ◽  
N Ladommatos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Injection System ◽  
Part Load ◽  
Piston Bowl

The piston bowl design is one of the most important factors that affect the air-fuel mixing and the subsequent combustion and pollutant formation processes in a direct-injection diesel engine. The bowl geometry and dimensions, such as the pip region, bowl lip area, and toroidal radius, are all known to have an effect on the in-cylinder mixing and combustion process. In order to understand better the effect of re-entrant geometry, three piston bowls with different toroidal radii and lip shapes were investigated using computational fluid dynamics engine modelling. KIVA3V with improved submodels was used to model the in-cylinder flows and combustion process, and it was validated on a high-speed direct-injection engine with a second-generation common-rail fuel injection system. The engine's performance, in-cylinder flow, and combustion, and emission characteristics were analysed at maximum power and maximum torque conditions and at part-load operating conditions. Three injector protrusions and injection timings were investigated at full-load and part-load conditions.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

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