Systematic Investigation of Fuel Film Evaporation

2018 ◽  
Author(s):  
Florian Schulz ◽  
Frank Beyrau
Keyword(s):  
Systematic Investigation ◽  
Fuel Film ◽  
Film Evaporation

Combining Instantaneous Temperature Measurements and CFD for Analysis of Fuel Impingement on the DISI Engine Piston Top

2009 ◽  
Author(s):  
Kukwon Cho ◽  
Ronald O. Grover ◽  
Dennis Assanis ◽  
Zoran Filipi ◽  
Gerald Szekely ◽  
...  
Keyword(s):  
Film Thickness ◽  
Heat Loss ◽  
Cfd Simulation ◽  
Computational Study ◽  
Fluid Dynamic ◽  
Direct Injection ◽  
Negative Temperature ◽  
Fuel Injector ◽  
Fuel Film ◽  
Film Evaporation

A two-pronged experimental and computational study was conducted to explore the formation, transport, and vaporization of a wall film located on the piston surface within a four-valve, pent roof, direct-injection spark-ignition (DISI) engine, with the fuel injector located between the two intake valves. Negative temperature swings were observed at three piston locations during early injection, thus confirming the ability of fast-response thermocouples to capture the effects of impingement and heat loss associated with fuel film evaporation. Computational Fluid Dynamic (CFD) simulation results demonstrated that the fuel film evaporation process is extremely fast under conditions present during intake. Hence, the heat loss measured on the surface can be directly tied to the heating of the fuel film and its complete evaporation, with the wetted area estimated based on CFD predictions. This finding is critical for estimating the local fuel film thickness from measured heat loss. The simulated fuel film thickness and transport corroborated well temporally and spatially with measurements at thermocouple locations directly in the path of the spray, thus validating the spray and impingement models. Under the strategies tested, up to 23% of fuel injected impinges upon the piston and creates a fuel film with thickness of up to 1.2 μm. In summary, the study demonstrates the usefulness of heat flux measurements to quantitatively characterize the fuel film on the piston top and allows for validation of the CFD code.

Research on Transient Fuel-Film Compensation Control Strategy for a Port-Fuel-Injected Engine

2011 ◽  
Vol 383-390 ◽  
pp. 1195-1201
Author(s):  
Jian Hao Zhou ◽  
Yin Nan Yuan ◽  
Kai Wu ◽  
Jia Yi Du
Keyword(s):  
Perturbation Method ◽  
Control Strategy ◽  
Wave Perturbation ◽  
Fuel Film ◽  
Transient Conditions ◽  
Evaporation Model ◽  
Square Wave ◽  
Film Evaporation ◽  
Compensation Control ◽  
New Strategy

The fuel-film evaporation model and transient fuel-film compensator model were established. By virtue of Simulink, the validity of above models were verified. The square wave perturbation method was introduced. Basing numerous calibration, the fuel-film compensation strategy including zoned compensation and damping factors ware proposed. This new strategy can compensate in-cylinder fuel fluctuation effectively during transient conditions.

Combining Instantaneous Temperature Measurements and CFD for Analysis of Fuel Impingement on the DISI Engine Piston Top

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Kukwon Cho ◽  
Ronald O. Grover ◽  
Dennis Assanis ◽  
Zoran Filipi ◽  
Gerald Szekely ◽  
...  
Keyword(s):  
Film Thickness ◽  
Heat Loss ◽  
Cfd Simulation ◽  
Computational Study ◽  
Direct Injection ◽  
Negative Temperature ◽  
Spark Ignition Engine ◽  
Fuel Injector ◽  
Fuel Film ◽  
Film Evaporation

A two-pronged experimental and computational study was conducted to explore the formation, transport, and vaporization of a wall film located at the piston surface within a four-valve, pent-roof, direct-injection spark-ignition engine, with the fuel injector located between the two intake valves. Negative temperature swings were observed at three piston locations during early injection, thus confirming the ability of fast-response thermocouples to capture the effects of impingement and heat loss associated with fuel film evaporation. Computational fluid dynamics (CFD) simulation results indicated that the fuel film evaporation process is extremely fast under conditions present during intake. Hence, the heat loss measured on the surface can be directly tied to the heating of the fuel film and its complete evaporation, with the wetted area estimated based on CFD predictions. This finding is critical for estimating the local fuel film thickness from measured heat loss. The simulated fuel film thickness and transport corroborated well temporally and spatially with measurements at thermocouple locations directly in the path of the spray, thus validating the spray and impingement models. Under the strategies tested, up to 23% of fuel injected impinges upon the piston and creates a fuel film with thickness of up to 1.2 μm. In summary, the study demonstrates the usefulness of heat flux measurements to quantitatively characterize the fuel film on the piston top and allows for validation of the CFD code.

Research on Transient Fuel-Film Compensation Control Strategy for a Port-Fuel-Injected Engine

2012 ◽  
Vol 462 ◽  
pp. 434-441
Author(s):  
Jian Hao Zhou ◽  
Yin Nan Yuan ◽  
Kai Wu ◽  
Jia Yi Du
Keyword(s):  
Perturbation Method ◽  
Control Strategy ◽  
Wave Perturbation ◽  
Fuel Film ◽  
Transient Conditions ◽  
Evaporation Model ◽  
Square Wave ◽  
Film Evaporation ◽  
Compensation Control ◽  
New Strategy

The fuel-film evaporation model and transient fuel-film compensator model were established. By virtue of Simulink, the validity of above models were verified. The square wave perturbation method was introduced. Basing numerous calibration, the fuel-film compensation strategy including zoned compensation and damping factors ware proposed. This new strategy can compensate in-cylinder fuel fluctuation effectively during transient conditions.

Emission Performance of a Micro Gas Turbine LPP-Combustor With Fuel Film Evaporation

2003 ◽  
Author(s):  
O. Liedtke ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Fuel Film ◽  
Emission Performance ◽  
Exhaust Gases ◽  
Micro Gas Turbine ◽  
Flame Tube ◽  
Film Evaporation ◽  
The Impact

The present paper describes the emission performance of a newly designed liquid fuelled micro gas turbine combustor. In order to reduce pollutant emissions, in particular nitrogen oxides NOx, lean premixed pre-vaporized combustion is utilized. Both, combustor inlet pressure and temperature are very low due to the thermodynamic cycle conditions chosen. As a consequence, the heat available for fuel spray evaporation is not sufficient. The present combustor concept therefore uses fuel film evaporation on the hot inner surface of a premix tube. The heat for evaporating the liquid fuel film is provided by the outer counter flow of hot exhaust gases. To establish almost adiabatic conditions within the reaction zone the flame tube features a multi-layered design, consisting of ceramic rings forming the inner wall, an insulation compliant layer, and the outer metal casing. To demonstrate the potential for reducing pollutant emissions overall NOx and CO concentrations of the exhaust gases have been measured and analyzed. The impact of combustor loading parameter, equivalence ratio, staging of the combustion, and ratio between calculated reaction times and mean residence times on the formation of pollutant emissions is investigated in detail. Furthermore, the impact of the flame tube volume on pollutant emissions and combustion stability is considered at various operating conditions. Measured pollutant emissions indicate the great potential for pollutant reduction that is associated with the specific geometry of the combustor.

Design Study of a Lean Premixed Prevaporized Counter Flow Combustor for a Micro Gas Turbine

2002 ◽  
Author(s):  
O. Liedtke ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Gas Turbine ◽  
Experimental Tests ◽  
Fuel Mixture ◽  
Flame Stabilization ◽  
International Standards ◽  
Pollutant Emissions ◽  
Fuel Film ◽  
Micro Gas Turbine ◽  
Film Evaporation ◽  
Lean Premixed

The present paper describes a new burner for a micro gas turbine utilizing the lean premixed prevaporized (LPP) combustion. The major objective of the new combustor concept is to achieve low pollutant emissions, in particular carbon monoxide (CO) and nitrogen oxide (NOx). Therefore, a homogeneous air fuel mixture is imperative for a lean combustion. Due to the thermodynamic cycle conditions of the micro gas turbine, the combustion air temperature is too low for an intense evaporation of a liquid fuel droplet spray. The new combustor concept therefore, is based on fuel film evaporation on the hot inner surface of a premix tube. The heat required for fuel film evaporation is transferred from the hot combustion gases, flowing along the outer surface of the tube, through the tube wall. The combustor wall is a multi-layered assembly consisting of a ceramic inner liner, a compliant layer, and the outer metal casing. This design allows almost adiabatic combustion to be established. The design process of the combustor is assisted by comprehensive numerical studies of droplet and fuel film evaporation. The commercial CFD code “CFD-RC” has been utilized to investigate the isothermal flow of the combustor. The vortex flow of the burner, which provides for flame stabilization, is described in detail. First experimental tests have been conducted. Measured pollutant concentrations of the exhaust gases meet international standards and demonstrate the great potential of the new combustor.

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