High-speed chemical species tomography in a multi-cylinder automotive engine

Tomographic imaging of the liquid and vapour fuel distributions in a single-cylinder direct-injection gasoline engine

“…A brief literature review of chemically-selective optical tomography has been presented in [5]. Further work relevant to in-cylinder engine application has been published recently by Sanders et al [19].…”

“…The method of Near Infra-Red Absorption Tomography (NIRAT) for in-cylinder gaseous fuel imaging has previously been applied by the authors to a multi-cylinder engine [5], in a form whereby it is chemically selective specifically to long-chain hydrocarbon molecules. However, as pointed out in [6], optical tomography in non-chemically selective form also has the potential to image the in-cylinder spatial distribution of sprays.…”

“…The reference wavelength,   , is chosen to be 1651 nm, and both wavelengths are provided by diode lasers. The measurement of the transmitted intensity at each of the two wavelengths is performed simultaneously using a dual-frequency lock-in technique, described in detail by Wright et al [5]. The PCI measurement for each beam is performed and recorded at high speed, 100 kilosamples/s (kS/s), but subsequent filtering typically reduces the imaging rate, e.g.…”

“…Whilst the work reported in the present paper did not use the bespoke system for optical access and optical transmission (launch) and receive reported in [5], the remainder of the system is still referred to here by the name IMAGER. The IMAGER electronics was designed from the outset to cope with the effects of fuel sprays upon the low-frequency properties of the received light from each beam, which have been discussed in [6], and the present paper describes the first application of IMAGER to a GDI engine.…”

“…The opto-electronic system used was previously reported in [5], along with its application to stage (b) above, in a Ford Duratec in-line 4-cylinder Port-Fuel-Injected (PFI) engine. Whilst the work reported in the present paper did not use the bespoke system for optical access and optical transmission (launch) and receive reported in [5], the remainder of the system is still referred to here by the name IMAGER.…”