TY - JOUR

T1 - Comparison of the Optical Connectivity Method to X-Ray spray measurements in the near field of a diesel injector

AU - Gröger, Karsten

AU - Kaiser, Max

AU - Wang, Jin

AU - Dinkelacker, Friedrich

N1 - Funding information: Part of this work is supported by the US Department of Energy, Basic Energy Sciences , Office of Science , under Contract No. 852W5 .

PY - 2019

Y1 - 2019

N2 - For diesel sprays, the primary breakup processes are only rarely understood due to the high optical density and the resulting difficulties to measure them with extremely high spatial and sufficient temporal resolution. The Optical Connectivity Method (OCM) has been proposed in the last years to allow the determination of the breakup length of the connected liquid core, thus giving a measurement quantity of the primary breakup. In this work, an improved optical setup of the OCM is applied to a three-hole test injector nozzle where several measurement techniques are compared currently under well-defined conditions up to 100 MPa injection pressure. In this work, the direct comparison with X-Ray measurements done at the Advanced Photon Source of the Argonne National Laboratory will be described. This allows an evaluation of the OCM technique and a comparison of the different measurement quantities in the first 500 μm range of the spray. The structure of the spray is measured by X-Ray phase contrast imaging and the fuel mass distribution is measured by X-Ray absorption imaging. A detailed comparison of the two X-Ray techniques and the OCM technique has been possible for the first time. It is found that the measurement data of the spray near field are very congruent with all three methods. Due to this comparison, the measurement of the non-perturbed length, which describes the distance from the nozzle orifice up to the point where the formation of surface disturbances is starting, by the OCM is validated for the first time. Within this non-perturbed length of the spray, the OCM signal is weak before it starts to illuminate from the scattering of the perturbed surface. Thus, the OCM technique can deliver two characteristic length scales, the non-perturbed length and the breakup length, characterizing the primary spray breakup.

AB - For diesel sprays, the primary breakup processes are only rarely understood due to the high optical density and the resulting difficulties to measure them with extremely high spatial and sufficient temporal resolution. The Optical Connectivity Method (OCM) has been proposed in the last years to allow the determination of the breakup length of the connected liquid core, thus giving a measurement quantity of the primary breakup. In this work, an improved optical setup of the OCM is applied to a three-hole test injector nozzle where several measurement techniques are compared currently under well-defined conditions up to 100 MPa injection pressure. In this work, the direct comparison with X-Ray measurements done at the Advanced Photon Source of the Argonne National Laboratory will be described. This allows an evaluation of the OCM technique and a comparison of the different measurement quantities in the first 500 μm range of the spray. The structure of the spray is measured by X-Ray phase contrast imaging and the fuel mass distribution is measured by X-Ray absorption imaging. A detailed comparison of the two X-Ray techniques and the OCM technique has been possible for the first time. It is found that the measurement data of the spray near field are very congruent with all three methods. Due to this comparison, the measurement of the non-perturbed length, which describes the distance from the nozzle orifice up to the point where the formation of surface disturbances is starting, by the OCM is validated for the first time. Within this non-perturbed length of the spray, the OCM signal is weak before it starts to illuminate from the scattering of the perturbed surface. Thus, the OCM technique can deliver two characteristic length scales, the non-perturbed length and the breakup length, characterizing the primary spray breakup.

KW - Breakup length

KW - Non-perturbed length

KW - Optical Connectivity Method

KW - Primary breakup

KW - X-Ray diagnostics

UR - http://www.scopus.com/inward/record.url?scp=85055637545&partnerID=8YFLogxK

U2 - 10.1016/j.proci.2018.09.017

DO - 10.1016/j.proci.2018.09.017

M3 - Article

AN - SCOPUS:85055637545

VL - 37

SP - 3271

EP - 3278

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

SN - 1540-7489

IS - 3

ER -