Subproject C01
Experimental characterization of in-cylinder near-wall flow and combustion processes

Team

  Name Contact
Dr.-Ing. habil. Benjamin Böhm
+49 6151 16-28913
L6|01 102
M.Sc. Jannick Erhard
+49 6151 16-28907
L6|01 123

At a glance

In the video, Marius Schmidt presents project C01: In-cylinder processes – experiments.

Motivation

Flame-wall interactions play a crucial role in technically relevant enclosed combustion systems as in internal combustion engines. Heat losses over the engine walls substantially impact efficiencies and emissions. For safe engine operation the resulting thermal loads on the engine components need to be limited, this requires reliable thermal management. The current trend towards smaller engine displacement volumes together with increasing energy densities leads additionally to increasing surface-to-volume-ratios. Hence, near-wall phenomena are of increasing interest, but not comprehensively understood or described.

Objectives

Measurements of the in-cylinder core flow are commonly performed within IC engines while measurements in the vicinity of walls are rare. This subproject aims for an experimental characterization of these flame-wall interactions within a spark-ignition engine. This includes the near-wall flow and combustion processes as well as their coupling with the in-cylinder core flow. The aim is to gain an understanding of the relevant physical processes and to provide data for the validation of engine simulations performed within the numerical subprojects of this initiative.

While in the recent years one-phase-flow and homogeneous operation were in focus, the complexity is increased in the second funding period with the addition of a fluid phase. Direct injection is used to investigate wall wetting and mixture inhomogeneities near the walls.

Flame-wall interaction in internal combustion engines.
Flame-wall interaction in internal combustion engines.

Previous Findings

High resolution optical techniques have been used to resolve the flow, including the small-scale boundary layer, and to analyze the interaction between the flow, flame propagation, and piston wall surface. These measurements reveal that strong deviations between the flows of the motored and fired operation cases as well as between common models exist. In addition it was proven that the flame influences the near-wall flow development.

PTV-visualization of the near-wall boundary flow in high resolution (coin for comparison).
PTV-visualization of the near-wall boundary flow in high resolution (coin for comparison).

Approach

The experiments are performed within an experimental spray-guided, direct-injection, spark-ignition engine with a centrally mounted injector. The engine is optically accessible through a quartz glass window in the piston and a quartz glass liner. The entire engine test bench was especially designed for validation purposes. This includes a simplified geometry, comprehensively characterized boundary conditions and a reproducible engine operation. The test bench is equipped with various temperature and pressure measurement systems to control the boundary conditions and for high-resolution in-cylinder pressure measurements. These quantities are recorded and available for all experiments.

The engine characterization builds upon the acquired data from motored engine operation without fuel injection and fired operation with a homogeneous mixture. The complexity is now successively increased by adding inhomogeneous mixtures. Investigating these mixing processes and the following heat release is facilitated by implementing a Spray-G injector for direct injection and furthermore a single-hole injector for targeted wall wetting. A comprehensive database already exists for the in-cylinder flow which is used by several groups worldwide for model validation within the context of the “Darmstadt Engine Workshop.” This database is successively extended by engine operation conditions including combustion and mixture preparation.

Current Work

Current objectives include the continued characterization of the in-cylinder flow with high-speed and high-resolution diagnostics. Furthermore the spray formation, spray-wall as well as spray-flow interaction will be captured. Next to wall temperature measurements additional gas phase temperature measurements will be applied and complemented by emission measurements. Combining these methods in simultaneous measurements enables correlated analysis of these complex processes.

Cooperations

The main goal of this subproject is to improve the general knowledge of these near wall processes. In addition, these measurements also aid the modelling of internal combustion engine flows (B03, C03) by providing indispensable validation data. Laser absorption spectroscopy for emission diagnostics, which are developed in A05 in close collaboration with this subproject, and are applied to the engine. Synergy effects related to the usage of experimental equipment and improvement or adaption of optical measurement methods arise with other subprojects (A04, A06, C02).

The Spray-G injector used in this project originates from the Engine Combustion Network, a international collaboration with focus on engine sprays. The shared goal is to provide a well characterized experimental and computational platform for engine spray research.

ECN – information

Visualization of the injection-spray; pool-fire on the piston wall surface.
Visualization of the injection-spray; pool-fire on the piston wall surface.
  • Auernhammer, A., Bonarens, M., Goet, G., et al.: An intensity-based LIF measurement technique to quantify film thicknesses in the air gap of an electric motor with direct liquid cooling. Exp Fluids, 66, 50, 10.1007/s00348-025-03976-4, 2025.
  • Auernhammer, A., Bonarens, M., Goet, G., Wagner, S., Schorr, J., Dreizler, A., Böhm, B.: An intensity-based LIF Measurement Technique to Quantify Film Thicknesses in the Air Gap of an Electric Motor with Direct Liquid Cooling. 10.1007/s00348-025-03976-4, 2025.
  • Schmidt, M., et al.: Soot formation as a function of flow, flame and mixing field above evaporating fuel films in an optically accessible engine. Proc Combust Inst, 40 (1-4), 105605, 10.1016/j.proci.2024.105605, 2024.
  • Lien, H.-P., Welch, C., Li, Y., Pati, A., Hasenzahl, M., Sadiki, A., Böhm, B., Hasse, C.: Spray formation and spray-wall-flow interaction in a gasoline direct-injection (GDI) engine under early-injection conditions – a flow bench study. International Journal of Engine Research, 25(8):1516-1536, 10.1177/14680874241239098, 2024.
  • Johe, P., Zentgraf, F., Greifenstein, M., Böhm, B., Dreizler, A.: Effects of elevated pressure on thermochemical states of turbulent flame-wall interaction studied by multi-parameter laser diagnostics. Combustion and Flame, 260, 113214, 10.1016/j.combustflame.2023.11321, 2024.
  • Lien, H.-P., Welch, C., Pati, A., Hasenzahl, M., Böhm, B., Hasse, C., Jakirlic, S.: Characterization of near-wall flow and in-cylinder free-stream turbulence during the intake phase of a direct-injection engine: a flow bench study. International Journal of Heat and Fluid Flow, 107:109414, 10.1016/j.ijheatfluidflow.2024.109414, 2024.
  • Schmidt, M., Welch, C., Illmann, L., Dreizler, A., Böhm, B.: High-speed measurements and conditional analysis of boundary-layer flows at engine speeds up to 2500 rpm in a motored IC engine. 39th International Symposium on Combustion, Proceedings of the Combustion Institute 39, accepted for oral presentation. 10.1016/j.proci.2022.07.199, 2023.
  • Ding, Z., Truffin, K., Jay, S., Schmidt, M., Foucher, F., Borée, J.: On the Use of LES and 3D Empirical Mode Decomposition for Analyzing Cycle-to-Cycle Variations of In-Cylinder Tumbling Flow. 10.1007/s10494-023-00405-6, 2023
  • Chang, C. Y., Krumbein, B., Bopp, M., Basara, B., Sadiki, A., Hasse, C., Jakirlic, S.: Structural flow properties in IC engine-relevant piston-cylinder configurations: an eddy-resolving modelling study. SAE Technical Paper, 2022-01-0399, 2022.
  • von Deyn, L.H., Schmidt, M., Örlü, R., Stroh, A., Kriegseis, J., Böhm, B., Frohnapfel, B.: Ridge-type roughness: from turbulent channel flow to internal combustion engine. Exp Fluids, 10.1007/s00348-021-03353-x, 2022.
  • Fach, C., Rödel, N., Schorr, J., Krüger, C., Dreizler, A., Böhm, B.: Multi-parameter imaging of in-cylinder processes during transient engine operation for the investigation of soot formation. International Journal of Engine Research, 10.1177/14680874211019976, 2021.
  • Pati, A., Paredi, D., Welch, C., Schmidt, M., Geschwindner, C., Böhm, B., Lucchini, T., D’Errico, G., Hasse, C.: Numerical and experimental investigations of the early injection process of Spray G in a constant volume chamber and an optically accessible DISI engine. International Journal of Engine Research, 10.1177/14680874211039422, 2021.
  • Schmidt, M., Ding, C.-P., Peterson, B., Dreizler, A., Böhm, B.: Near-wall flame and flow measurements in an optically accessible SI engine. Flow Turbulence Combust, 10.1007/s10494-020-00147-9, 2021.
  • Welch, C., Schmidt, M., Geschwindner, C., Wu, S., Wooldridge, M.S., Böhm, B.: The influence of in-cylinder flows and bulk gas density on early Spray G injection in an optical research engine. International Journal of Engine Research, 10.1177/14680874211042320, 2021.
  • Zentgraf, F., Johe, P., Cutler, A.D., Barlow, R.S., Böhm, B., Dreizler, A.: Classification of flame prehistory and quenching topology in a side-wall quenching burner at low-intensity turbulence by correlating transport effects with CO 2 , CO and temperature. Combustion and Flame, 10.1016/j.combustflame.2021.111681, 2021.
  • Ding, C.-P., Vuilleumier, D., Kim, N., Reuss, D.L., Sjöberg, M., Böhm, B.: Effect of engine conditions and injection timing on piston-top fuel films for stratified direct-injection spark-ignition operation using E30. International Journal of Engine Research, 10.1177/1468087419869785, 2020.
  • Geschwindner, C., Kranz, P., Welch, C., Schmidt, M., Böhm, B., Kaiser, S.A., De la Morena, J.: Analysis of the interaction of Spray G and in-cylinder flow in two optical engines for late gasoline direct injection. International Journal of Engine Research, 10.1177/1468087419881535, 2020.
  • Haussmann, M., Ries, F., Jeppener-Haltenhoff, J.B., Li, Y., Schmidt, M., Welch, C., Illmann, L., Böhm, B., Nirschl, H., Krause, M.J., Sadiki, A.: Evaluation of a near-wall-modeled large eddy lattice Boltzmann method for the analysis of complex flows relevant to IC engines. Computation, 10.3390/computation8020043, 2020.
  • Hill, H., Ding, C.-P., Baum, E., Böhm, B., Dreizler, A., Peterson, B.: An application of tomographic PIV to investigate the spray-induced turbulence in a direct-injection engine. International Journal of Multiphase Flow, 10.1016/j.ijmultiphaseflow.2019.103116, 2019.
  • Peterson, B., Baum, E., Dreizler, A., Böhm, B.: An experimental study of the detailed flame transport in a SI engine using simultaneous dual-plane OH-LIF and stereoscopic PIV. Combustion and Flame, 10.1016/j.combustflame.2018.12.024, 2019.
  • Bürkle, S., Biondo, L., Ding, C.-P., Honza, R., Ebert, V., Böhm, B., Wagner, S.: In-cylinder temperature measurements in a motored IC engine using TDLAS. Flow Turbulence Combust, 10.1007/s10494-017-9886-y, 2018.
  • Forooghi, P., Weidenlener, A., Magagnato, F., Böhm, B., Kubach, H., Koch, T., Frohnapfel, B.: DNS of momentum and heat transfer over rough surfaces based on realistic combustion chamber deposit geometries. International Journal of Heat and Fluid Flow, 10.1016/j.ijheatfluidflow.2017.12.002, 2018.
  • Jainski, C., Rißmann, M., Jakirlic, S., Böhm, B., Dreizler, A.: Quenching of premixed flames at cold walls: effects on the local flow field. Flow Turbulence Combust, 10.1007/s10494-017-9836-8, 2018.
  • Renaud, A., Ding, C.-P., Jakirlic, S., Dreizler, A., Böhm, B.: Experimental characterization of the velocity boundary layer in a motored IC engine. International Journal of Heat and Fluid Flow, 10.1016/j.ijheatfluidflow.2018.04.014, 2018.
  • Bode, J., Schorr, J., Krüger, C., Dreizler, A., Böhm, B.: Influence of three-dimensional in-cylinder flows on cycle-to-cycle variations in a fired stratified DISI engine measured by time-resolved dual-plane PIV. Proceedings of the Combustion Institute, 10.1016/j.proci.2016.07.106, 2017.
  • He, C., Kuenne, G., Yildar, E., van Oijen, J., di Mare, F., Sadiki, A., Ding, C.-P., Baum, E., Peterson, B., Böhm, B., Janicka, J.: Evaluation of the flame propagation within an SI engine using flame imaging and LES. Combustion Theory and Modelling, 10.1080/13647830.2017.1343498, 2017.
  • Honza, R., Ding, C.-P., Dreizler, A., Böhm, B.: Flame imaging using planar laser induced fluorescence of sulfur dioxide. Appl. Phys. B, 10.1007/s00340-017-6823-7, 2017.
  • Jainski, C., Rißmann, M., Böhm, B., Dreizler, A.: Experimental investigation of flame surface density and mean reaction rate during flame–wall interaction. Proceedings of the Combustion Institute, 10.1016/j.proci.2016.07.113, 2017.
  • Jainski, C., Rißmann, M., Böhm, B., Janicka, J., Dreizler, A.: Sidewall quenching of atmospheric laminar premixed flames studied by laser-based diagnostics. Combustion and Flame, 10.1016/j.combustflame.2017.05.020, 2017.
  • Peterson, B., Baum, E., Ding, C.-P., Michaelis, D., Dreizler, A., Böhm, B.: Assessment and application of tomographic PIV for the spray-induced flow in an IC engine. Proceedings of the Combustion Institute, 10.1016/j.proci.2016.06.114, 2017.
  • Stiehl, R., Bode, J., Schorr, J., Krüger, C., Dreizler, A., Böhm, B.: Influence of intake geometry variations on in-cylinder flow and flow–spray interactions in a stratified direct-injection spark-ignition engine captured by time-resolved particle image velocimetry. International Journal of Engine Research, 10.1177/1468087416633541, 2016.
  • Zentgraf, F., Baum, E., Böhm, B., Dreizler, A., Peterson, B.: On the turbulent flow in piston engines: Coupling of statistical theory quantities and instantaneous turbulence. Physics of Fluids, 10.1063/1.4945785, 2016.