Linking cavitation erosion in a multi-hole injector with spray and combustion development

Abstract

It is well known that cavitation erosion in fuel injectors can prevent reliable engine performance after only several thousand hours of operation. However, current simulation tools lack the ability to link flow predictions within the fuel injector to both the efficacy of combustion strategies and lifetime of the injector. Multiphase flow simulation predictions were studied and compared between an informed baseline injector geometry and an x-ray scanned eroded injector geometry. Overall, erosion was found to decrease the fuel mass delivery and injection velocities. A two-stage static coupling approach was employed to link the predicted injection conditions from non-eroded and eroded injectors with the external spray simulations under reacting conditions. Combustion modeling in this coupled approach was carried out using the Unsteady Flamelet Progress Variable approach with a detailed chemical mechanism for ndodecane, comprising of 2,755 species and 11,173 reactions. Erosion in the injectors led to lower rates of spray penetration in comparison to the baseline configurations. Analysis of the reacting spray simulations revealed an insensitivity of ignition to erosion, yet shorter lift off lengths and higher levels of the soot precursor acetylene were predicted in the eroded injector.

Deep Learning for improving the efficiency of dimensional measurement workflows with high-resolution X-ray computed tomography

“…The surface computed from the CT data is defined as the boundary separating the voxels belonging to the metal and air (orifice passages) respectively. This surface defines the walls of the flow passages and are known to bear precursor sites for erosion during long-term injector operation [6,7]. Hence, not only is it important to measure the orifice critical dimensions but also the surface roughness introduced by micrometer-scale metal fragments leftover from the manufacturing process.…”

Experimental Investigation of Cavitation-Induced Erosion Using X-Ray Imaging and Tomography

“…Experiments were performed at the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory (Kastengren et al, 2012a). The injector is a Bosch CRIN 3 diesel injector with its tip partially removed, which allows different nozzles to be installed (Yasutomi et al, 2020;Magnotti et al, 2021a). The nozzles were manufactured from Al 6061-T6 to observe erosion with fewer injection events relative to steel and within laboratory-relevant timescales (Magnotti et al, 2019).…”

“…While this is fewer holes than a production diesel injector, it allows for a clear visualization of a hole in projection without overlap from neighboring holes. The three holes also have a sharp inlet radius of curvature, which is intended to promote cavitation (Magnotti et al, 2021a). The injector is mounted on a rotational stage, which is then sealed in a pressure chamber with X-ray transparent windows.…”