Scott E. Parrish

Spray measurement technology: a review

Sprays are among the most intellectually challenging and practically important topics in fluid mechanics. This paper reviews needs, milestones, challenges, and a broad array of techniques for spray measurement. In addition, tabular summaries provide cross-referenced entry points to the vast literature by organizing over 300 citations according to key spray phenomena, physical parameters and measurement techniques for each of the principal spray regions (nozzle internal flow, near-field spray-formation region, far-field developed spray, and spray-wall interaction). The article closes with perspectives on some current issues in spray research, including the cost and complexity of apparatus for spray physics and spray engineering, the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.

Gasoline Fuel Injector Spray Measurement and Characterization – A New SAE J2715 Recommended Practice

With increasingly stringent emissions regulations and concurrent requirements for enhanced engine thermal efficiency, a comprehensive characterization of the automotive gasoline fuel spray has become essential. The acquisition of accurate and repeatable spray data is even more critical when a combustion strategy such as gasoline direct injection is to be utilized. Without industry-wide standardization of testing procedures, large variablilities have been experienced in attempts to verify the claimed spray performance values for the Sauter mean diameter, Dv90, tip penetration and cone angle of many types of fuel sprays. A new SAE Recommended Practice document, J2715, has been developed by the SAE Gasoline Fuel Injection Standards Committee (GFISC) and is now available for the measurement and characterization of the fuel sprays from both gasoline direct injection and port fuel injection injectors. A primary motivation for the development of the standardized procedures for test configuration, data acquisition, data reduction and reporting was to achieve significant reductions in the test-to-test and laboratory-to-laboratory variabilities of such reported spray data. All of the major areas of fuel injector spray testing and characterization are addressed in detail in the document, including spray imaging, high-resolution patternation and drop sizing by both phase-Doppler interferometry and laser diffraction. Valuable lessons regarding the definitions and interpretations of commonly-used spray parameters were learned during the development of the J2715 document, and these are presented and discussed. Based upon the five years of committee discussions and consensus decisions, five key recommendations on fuel spray measurement and characterization are made to the worldwide automotive industry. The first, and most important, recommendation is that the Recommended Practices in SAE J2715 be utilized by the spray laboratories of all automotive companies and injector 2008-01-1068 Gasoline Fuel Injector Spray Measurement and Characterization – A New SAE J2715 Recommended Practice

Quantitative Mixing Measurements and Stochastic Variability of a Vaporizing Gasoline Direct-Injection Spray

Spark-ignition direct-injection engines operating in a stratified, lean-burn regime offer improved engine efficiency; however, seemingly random fluctuations in stratified combustion that result in partial-burn or misfire prevent widespread implementation. Eliminating these poor combustion events requires detailed understanding of engine flow, fuel delivery, and ignition, but knowing the dominant cause is difficult because they occur simultaneously in an engine. This study investigated the variability in fuel–air mixture linked to fuel injection hardware in a near-quiescent pressure vessel at high-temperature conditions representative of late, stratified-charge injection. An eight-hole spark-ignition direct-injection spray was interrogated using high-speed schlieren and Mie-scatter imaging from multiple, simultaneous views to acquire the vapor and liquid envelopes of the spray. The mixture fraction of vaporized sections of the spray was then quantified at a plane between plumes using Rayleigh scattering. Probability contours of the line-of-sight vapor envelope showed little variability between injections, whereas probability contours derived from planar, quantitative mixing measurements exhibit greater amounts of variability for lean-combustion-limit charge. The mixture field between plumes was characterized by multi-hole and end-of-injection dynamics that attract the plumes to each other and toward the injection axis, resulting in a liquid-fuel-droplet-dense merged central jet in the planar measurements. Supplemental long-working distance microscopy imaging showed the existence of fuel droplets far downstream in the region of the planar laser measurements.