In-cylinder Flow with Negative Valve Overlapping - Characterised by PIV Measurement

Wilson, T.; Haste, Martin J.; Xu, Hongming; Richardson, Steve; Yap, D.; Megaritis, Thanos

doi:10.4271/2005-01-2131

Cited by 11 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11 (d)) for NVO=120° compared to NVO=0°. This is completely consistent with PIV measurements results taken by Wilson et al [26] which provided quantitative flow characteristics of in-cylinder flows under NVO. In these PIV investigations, it was observed that NVO with reduced valve lift and duration generated intake flow velocities significantly higher than those found with typical positive overlapping valve strategies.…”

Section: Effect On In-cylinder Air Motion Before Fuel Injectionsupporting

confidence: 81%

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

Peng

Jia

2008

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

A three-dimensional CFD modeling was carried out to investigate effects of VVT/VVA on gas exchange and fuel-air mixing processes in a diesel HCCI engine with early fuel injection. Four VVT/VVA strategies were conducted for this study: i) NVO strategy with fixed EVO and IVC timings but variable valve lifts -referred as NVO Strategy; ii) NVO strategy with fixed valve profiles but variable EVO and IVC timings -referred as EVO Strategy; iii) NVO strategy with fixed valve lifts and fixed EVO and IVC timings but variable EVO and IVC timings -referred as EVC Strategy; iv) VVA with just variable valve lifts -referred as VMAX Strategy. The results indicate that suitable NVO settings will enhance in-cylinder tumble and then increase turbulence intensity before compression-end, though the increased NVO has a negative contribution to swirl ratio. It was found that reducing valve lifts alone is not an efficient way to retain the residual gas, but the function of reduced valve lifts will become significantly obvious by combining it with increasing NVO. For the effect of NVO on in-cylinder temperature, longer NVO will not only increase in-cylinder temperature due to higher residual gas rate, but also improve the in-cylinder temperature homogeneity. Lowering the maximum valve lift or increasing NVO, the unmixed region of in-cylinder charge shrinks. The rich fuel region expands because of the high intake velocity and enhanced turbulence intensity. This is beneficial to the forming of global homogeneous charge. It has been noted from the current study, as the droplet distribution may be influenced more by the in-cylinder air motion caused by NVO when the average droplet size is smaller, it is recommended that future studies explore the effects of VVT/VVA on diesel HCCI mixing and combustion with various advanced fuel injection strategies.

show abstract

Section: Effect On In-cylinder Air Motion Before Fuel Injectionsupporting

confidence: 81%

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

Peng

Jia

2008

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

show abstract

“…There are many experimental techniques that have been applied and are available to detect and either quantify or qualify flow conditions prevailing before the onset of combustion. These include flow visualisation, PIV [3,5], particle tracking velocimetry (PTV) [6] and Laser Doppler Anemometry (LDA) [4]. There also exist many techniques that can detect combustion phenomena such as ionisation probe sensors and Laser Induced Florescence (LIF) [7,9].…”

Section: Introductionmentioning

confidence: 99%

Optical Study of Flow and Combustion in an HCCI Engine with Negative Valve Overlap

Wilson

Richardson

et al. 2006

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

One of the most widely used methods to enable Homogeneous Charge Compression Ignition (HCCI) combustion is using negative valve overlapping to trap a sufficient quantity of hot residual gas. The characteristics of air motion with specially designed valve events having reduced valve lift and durations associated with HCCI engines and their effect on subsequent combustion are not yet fully understood. In addition, the ignition process and combustion development in such engines are very different from those in conventional spark-ignition or diesel compression ignition engines. Very little data has been reported concerning optical diagnostics of the flow and combustion in the engine using negative valve overlapping. This paper presents an experimental investigation into the in-cylinder flow characteristics and combustion development in an optical engine operating in HCCI combustion mode. PIV measurements have been taken under motored engine conditions to provide a quantitative flow characterisation of negative valve overlap in-cylinder flows. The ignition and combustion process was imaged using a high resolution charge coupled device (CCD) camera and the combustion imaging data was supplemented by simultaneously recorded in-cylinder pressure data which assisted the analysis of the images. It is found that the flow characteristics with negative valve overlapping are less stable and more valve event driven than typical spark ignition in-cylinder flows, while the combustion initiation locations are not uniformly distributed.

show abstract

Effect of engine parameters on in-cylinder flows in a two-stroke gasoline direct injection engine

2016

View full text Add to dashboard Cite

In-cylinder Flow with Negative Valve Overlapping - Characterised by PIV Measurement

Cited by 11 publications

References 9 publications

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

Optical Study of Flow and Combustion in an HCCI Engine with Negative Valve Overlap

Effect of engine parameters on in-cylinder flows in a two-stroke gasoline direct injection engine

Contact Info

Product

Resources

About