Needle lift profile influence on the vapor phase penetration for a prototype diesel direct acting piezoelectric injector

Abstract

Elsevier Payri, R.; Gimeno, J.; Viera, JP.; Plazas Torres, AH. (2013). Needle lift profile influence on the vapor phase penetration for a prototype diesel direct acting piezoelectric injector. Fuel. 113:257-265. doi:10.1016Fuel. 113:257-265. doi:10. /j.fuel.2013 and not injection pressure. Ambient temperature alone seems not to have and important effect on vapor penetration. Finally, the effects of the needle lift profile in the instant injection rate and vapor penetration are presented, confirming the strong relation between these three parameters, and confirming also that the needle lift plays a determinant role in the spray development, especially at the early stages of the injection process. Both boot and ramp shaped injections proved the ability to strongly influence the vapor penetration rate. In comparison to the square shaped injection, the effect of the ramp shaped injection delays the vapor penetration right from the start of injection while the effect of the boot shaped injection takes considerably longer to become noticeable. From the results, the needle lift control feature has proven to be a very versatile tool for engine designers to control the injection process as desired, opening a new path with a plenty of room for improvement.

Vapor phase penetration measurements with both single and double-pass Schlieren for the same injection event

“…The right side of Figure 5, depicts the effect of chamber density on the spray tip penetration. As observed in the previous case, both Schlieren arrangements capture the effect of density in the spray development in agreement with the literature [10,17]. However, even though the double-pass setup still depicts higher penetration values, the difference between the optical arrangements is reduced when decreasing the density, and reports almost identical values at the lowest level in the conditions tested.…”

“…The core of the segmentation algorithm is based in a fixed threshold intensity-sensitive method [3,5,10,15]. But to improve the contour detection capabilities, an image-temporal-derivative approach [9,16,17] was added.…”

“…This process is repeated for each time-step up to the end of injection. The SOI is calculated by extrapolating the penetration curve to zero, that is t(S = 0), with a quadratic fit [10,[17][18][19]. Since the high-temperature mirror in the double-pass setup makes it not possible to observe the first few millimeters of penetration, the SOI was calculated only with the SP data, and then copied to the double-pass data.…”

“…It is not only fundamental knowledge to understand how boundary conditions affect these variables, but the experimental data is necessary to validate computational tools, such as 1-D models or computational fluid dynamics (CFD). The two most common Schlieren configurations are single-pass (SP) [2,[5][6][7][8][9] and double-pass (DP) [3,[10][11][12][13]. Typically, the first setup is used for axially drilled single-orifice nozzles, where vessels with multiple optical accesses allow line of sight visualization.…”

Charge gradient microscopy

“…screen charge | atomic force microscopy | piezoresponse | charge scraping F erroelectric and piezoelectric materials have attracted great attention due to their applications in commercial markets such as a medical imaging (1-3), next generation inkjet printer heads (4), precision-positioning stages (5,6), fuel injectors in diesel engines (7,8), and memory devices (9,10). The macroscopic properties of ferroelectric and piezoelectric materials that make them appealing for current and future technologies can be more fully understood and improved through detailed knowledge of their domain structures at the nanoscale and mesoscale (11)(12)(13)(14)(15).…”