High-frequency wall heat flux measurement during wall impingement of a diffusion flame

Moussou, Julien; Pilla, Guillaume; Sotton, Julien; Bellenoue, Marc; Rabeau, Fabien

doi:10.1177/1468087419878040

Cited by 8 publications

(8 citation statements)

References 39 publications

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“…This is because the increase of injection pressure can increase T inj , making fuel droplets easier to evaporate during the spraying process, thereby reducing the strength of the impingement. However, increasing P inj can increase the spray velocity and increase the intensity of turbulence near the wall, thereby increasing the heat transfer effect on the high temperature surface 37 . From the above discussion, it can be concluded that the heat transfer of spray-wall impingement can be enhanced when fuel impinges with a large injection pressure on the wall.…”

Section: Resultsmentioning

confidence: 99%

Experimental investigation of heat transfer for diesel spray impingement on a high temperature wall

Guo

Zhang

Jin

et al. 2022

Sci Rep

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In this paper, the heat transfer characteristics of spray-wall impingement on a high temperature wall were studied by using a transient thermocouple and a one-dimensional finite-difference conduction model to obtain variations of wall temperature and heat flux. Results showed that increasing the injection pressure and decreasing the ambient temperature both caused an increase in surface heat flux and heat transfer coefficient. However, with the increase of the initial surface temperature from 200 to 600 °C, the surface heat flux and heat transfer coefficient first increased and then decreased, and reached the maximum at about 520 °C and 390 °C respectively, which was due to the change of heat transfer regime on the wall. The contribution of experimental factors descended in the order of initial surface temperature, injection pressure and ambient temperature. The dimensionless surface heat fluxes in terms of Biot and Fourier numbers were highly similar and a dimensionless correlation was developed to quantify this heat transfer behavior, which showed that the ratio of the thermal resistance of the high temperature wall to the thermal resistance of convection heat transfer on the wall surface changed almost linearly during the process of spray-wall impingement.

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Section: Resultsmentioning

confidence: 99%

Experimental investigation of heat transfer for diesel spray impingement on a high temperature wall

Guo

Zhang

Jin

et al. 2022

Sci Rep

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“…The first possibility is that the heat transfer coefficient linked to the aerodynamic motion of the jet is higher because of the higher injection pressure and therefore a higher jet velocity, as described previously for that setup. 26 The second one is that the flame temperature is higher at the higher injection pressure. According to Tatsumi et al, 9 the flame temperature increases as the injection pressure increases.…”

Section: Resultsmentioning

confidence: 99%

“…The output from the thermocouple was amplified and filtered (10 kHz low-pass filter), and recorded with a sampling frequency of 250 kHz. The heat flux was computed using Duhamel's integral from the temperature smoothed with a Tikhonov regularization (see the literature 26 for the thermocouple data processing details). With respect to the wall temperature, the peak values were almost equal within about 5 K, however, it is visible that the shapes are different.…”

Section: Comparison Between Mems Sensor and Thermocouplementioning

confidence: 99%

Application of a MEMS heat flux sensor to heat transfer research on an impinging diesel jet

Dejima

Nakabeppu

Moussou

et al. 2021

International Journal of Engine Research

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To clarify the mechanisms of heat transfer on an engine wall is an important challenge because the heat loss on the wall is one of the dominant factors that limit the thermal efficiency. A thin-film resistance type heat flux sensor fabricated with Micro-Electro-Mechanical Systems (MEMS) technologies was applied to research on the heat transfer of an impinging diesel jet. The MEMS sensor had a high sensitivity and multiple measurement points with a scale comparable to the turbulence of in-cylinder flow for the investigation of local instantaneous heat transfer characteristics in engines. Measurements of wall temperature and heat flux were conducted in a constant volume chamber under the reference conditions of Engine Combustion Network (ENC) Spray A with variations in injection pressure. As a result, the maximum heat flux and heat transfer coefficient reached about 5 MW/m2 and 3 MW/(m2 K), respectively. The results were compared to those obtained with a commercially available thermocouple, and both sensors produced similar trends. In addition, fluid motion near the wall was estimated from the heat flux fluctuations using a cross-correlation analysis. The relationship between heat transfer and flow was investigated in a dimensionless number fashion, and it was compared to a semi-theoretical prediction that was based on a steady state laminar flow heat transfer model.

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“…These mechanisms are not fully understood, and several recent papers have employed advanced diagnostic techniques to resolve the relationship between heat transfer and the local turbulence in the flow. 10–12 A recent study by Srna parallels the current work in that several different injection schedules were investigated in a diesel engine to understand the effect on local heat flux. 13 The experimental data set included fast-response surface temperature measurements of the cylinder liner with simultaneous optical diagnostics of the jet.…”

Section: Introductionmentioning

confidence: 85%

Influence of spray and combustion processes on piston temperatures and engine heat transfer in a high-output diesel engine

Tess

Korivi

Gingrich

et al. 2022

International Journal of Engine Research

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Simultaneous measurements of global engine heat transfer and subsurface piston temperatures were utilized to evaluate the potential of an extended duration combustion event to minimize heat rejection in a diesel engine. The combustion duration was parametrically varied by changing the injector orifice diameter (0.167, 0.196, and 0.230 mm) and fuel injection pressure (110–200 MPa) while exploring three high-output operating conditions. This investigation was limited to a single-pulse injection strategy while holding engine load constant to represent operating points at rated power and peak torque. For a constant combustion phasing, the results suggest the duration of the spray and combustion processes did not greatly influence gross indicated thermal efficiency (ITEg) or global heat transfer from the engine, except for extremely long combustion durations of approximately 50 crank-angle degrees or longer. At the longest combustion durations, there was a negative impact on ITEg and global heat transfer. Analysis of the steady-state piston temperature measurements at constant CA50 revealed two interesting, and opposite, trends: as the combustion duration was increased through a smaller orifice diameter injector, the piston temperatures increased by up to 60°C locally on the bowl rim; in contrast, as the combustion duration was increased through lower injection pressures, the piston temperatures decreased by up to 80°C locally on the bowl rim. CFD simulations coupled with a conjugate heat transfer model of the piston predicted the piston heat flux at the highest load operating condition. The CFD results qualitatively agreed with the piston temperature measurements in supporting the conclusion that orifice diameter had a stronger effect on piston heat flux than injection pressure. Overall, this research provides directional trends to engine designers and calibrators for optimizing the injection parameters for decreased engine heat transfer and managing piston temperatures.

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High-frequency wall heat flux measurement during wall impingement of a diffusion flame

Cited by 8 publications

References 39 publications

Experimental investigation of heat transfer for diesel spray impingement on a high temperature wall

Experimental investigation of heat transfer for diesel spray impingement on a high temperature wall

Application of a MEMS heat flux sensor to heat transfer research on an impinging diesel jet

Influence of spray and combustion processes on piston temperatures and engine heat transfer in a high-output diesel engine

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