Mapping of exhaust gas recirculation and combustion-residual backflow in the intake ports of a heavy-duty diesel engine using a multiplexed multi-species absorption spectroscopy sensor

Abstract

The combustion-residual backflow into the intake ports of a commercial diesel engine (Cummins ISX series) was spatiotemporally mapped using a multiplexed multi-species absorption spectroscopy sensor system; the resulting cycle- and cylinder-resolved measurements are applicable for assessing cylinder charge uniformity, control strategies, and computational fluid dynamics tools. On-engine measurements were made using four compact (3/8 in Outside Diameter) stainless steel probes which enabled simultaneous multi-point measurements, required minimal engine hardware modification, and featured a novel tip design for measurement of gas flows parallel to the probe axis. Three sensor probes were used to perform simultaneous backflow measurements in intake runners corresponding to three of the six engine cylinders, and a fourth probe was installed in the intake manifold plenum for tracking dynamics introduced by an external exhaust gas recirculation mixer. Near-crank-angle resolved measurements (5 kHz, that is, 1.2 crank angle resolution at 1000 RPM) were performed during steady-state engine operation at various levels of external exhaust gas recirculation to measure the gas properties and penetration distance of the backflow into the intake runners on a cylinder- and cycle-basis. Validation of computational fluid dynamics model results is also presented to demonstrate the utility of such measurements in advancing engine research.

Development of A Multi-Spectral Pyrometry Sensor for High-Speed Transient Surface-Temperature Measurements in Combustion-Relevant Harsh Environments

“…In contrast, the MRT solution in the transient tail is much slower because the fast-channel signals go to zero while the slow-channel signal remains and approaches zero at later times; this trend of the MRT solution to converge to progressively lower temperatures as the channel signals progressively drop below a threshold value, as is apparent in Figure 8 a, has been consistently observed in Blank conditions and is discussed more in relation to Figure 8 b. Nevertheless, even in this non-optimized configuration, Figure 8 a shows that the instrument resolves 37–115 μs onset transients (74–230 points at 2 MHz), which is equivalent to 0.4–1.4 cad at 2000 RPM and is suitable for resolving transients within individual intake and exhaust valve events [ 9 ].…”

“…Similarly, in gas turbine applications, accurate blade surface temperatures are critical to evaluating the effectiveness of cooling designs and for prolonging component thermal life [ 5 , 6 , 7 ]. Optical diagnostics are non-intrusive and allow fast (kHz rate) measurements of combustion transients such as temperature and species [ 8 , 9 , 10 ]. Such high-speed diagnostics can also be applied to implement real-time control strategies for reducing cycle-to-cycle variability in the combustion process [ 8 , 9 , 10 , 11 , 12 , 13 ].…”

“…Optical diagnostics are non-intrusive and allow fast (kHz rate) measurements of combustion transients such as temperature and species [ 8 , 9 , 10 ]. Such high-speed diagnostics can also be applied to implement real-time control strategies for reducing cycle-to-cycle variability in the combustion process [ 8 , 9 , 10 , 11 , 12 , 13 ].…”

Characterization of temporal variations and feedback timescales of exhaust gas recirculation gas properties using high-speed diode laser absorption spectroscopy for next-cycle control of cyclic variability

“…This sensor and its prior iterations have previously been used to perform high-speed measurements at various locations on internal combustion engines such as intake manifold, 17 turbocharger inlet, 18 and intake ports. 19 Even though all gas properties (temperature, pressure, (H 2 O), and (CO 2 )) were measured using this sensor, only the (CO 2 ) values are reported here. This is because the temperature and (H 2 O) values will be reduced by both the EGR cooler and the CAC, possibly removing any variations in those properties.…”