Test Data AC2-10

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Internal combustion engine flows for motored operation

Application Challenge AC2-10   © copyright ERCOFTAC 2024

Test data

Operational conditions

The engine was motored at 800 RPM, with 0.95 bar and 23° C intake air temperature as the base case. The cylinder head temperature was thermally controlled at 60° C. The engine operated with dry air with a relative humidity of 1.8%. Additionally, engine speed variations were performed (1500 and 2500 RPM). Unless otherwise stated the operational conditions are summarized in table 1.

Table 1: Engine operating parameters for the base case.

RPM	800 ±7 min-1
Cyl. Head, coolant temp. ( <Teng> )	60 ±1°C
Avg. Press. Intake 1 ( pin,1 )	0.95 ±0.002 bar
Avg. Press. Intake 2 ( pin,2 )	0.95 ±0.002 bar
Avg. Press. Exhaust ( pout )	1.00 ±0.016 bar
Intake temp. 1 ( <Tin,1> )	22.9 ±0.1°C
Intake temp. 2 ( <Tin,2> )	23.2 ±0.1°C
Exhaust temp. ( <Tout> )	33.2 ±0.5°C
Mass flow air in ( <min> )	11.4 kg/h ±2%
Mass flow air out ( <mout> )	11.4 kg/h ±2%
Humidity (Φ)	1.8% - RH
Intake Valve Opening (IVO)	325° TDC
Intake Valve Closing (IVC)	125° bTDC
Exhaust Valve Opening (EVO)	105° aTDC
Exhaust Valve Closing (EVC)	345° bTDC

The spark plug was removed and replaced with a threaded plug and the injector was inactive for the experiments. In-cylinder pressure as well as pressure and temperature in the intake and exhaust manifolds were recorded simultaneously for all experiments to monitor the engine and to provide boundary conditions for simulations. The ensemble-average and standard deviation in-cylinder pressure trace and pressure boundary conditions (p_in,1, p_in,2, and p_out) are shown in Figure 8. The blow-by past the piston rings was found to be below the precision of the rotary piston gas meter systems in the intake and exhaust (1.8% of intake flow).

Figure 8: Engine transient boundary conditions: a) intake and exhaust valve lift, b) in-cylinder pressure, c) intake manifold pressures (pin,1, pout), d) exhaust manifold pressure. Statistical values are based on 600 engine cycles. Negative CAD values indicate bTDC. This figure is reproduced with permission from [4].

Overview

The available data set on the in-cylinder flow field of the motored engine is summarized in this section. Figure 9 summarizes the available field-of-views (FOV) for the variety of PIV measurements, which are all centered within the central tumble plane at z=0mm.

The first two statistical moments (mean and rms) are available for the following data:

• Both in-plane velocity components for representative phases of the engine cycle at selected crank angles within a large FOV (65x65 mm²) from the statistically independent PIV measurements (PIV) resolving the global in-cylinder flow (large database: up to 2700 cycles).
• High resolution data of both in-plane velocity components within a small FOV (20x15 mm²) from the statistically independent PIV measurements (PIV (High Res.)) resolving the smaller scales.
• All three velocity components in the measurement plane within a FOV (47x35 mm²) from stereo-PIV (Stereo-PIV).
• All three velocity components within a 47×35×8 mm³ volume centered in the central tumble plane from tomographic-PIV (Tomo-PIV).
• Time resolved data of both in-plane velocities within a 54×54 mm² FOV over entire consecutive cycles (PIV (High-Speed)).

The imaged CADs together with the number of respective images are given in Table \ref{tab:expdata} for all operational conditions.

Figure 9: Phase-averaged flow field during intake at 270° bTDC showing the FOV for PIV, high resolution PIV, high speed PIV, stereo-PIV and tomographic PIV. This figure is taken from [4].

Table 2: Overview of the available experimental flow data.

PIV Technique	Engine Speed (RPM)	Intake flow	CAD imaged (bTDC, negative numbers refer to aTDC)	Number of images
Low repetition rate 2D2C PIV	800	Tumble	270, 90, -90, -270	2700
	800	Tumble	315, 260, 180, 45, -45, -160, -180, -315	600
	1500	Tumble	270, 90	600
	2500	Tumble	270, 90	600
2D2C High-resolution PIV	800	Tumble	270, 90, -90, -160, -180, -270	600
2D2C High-speed PIV	800	Tumble	360 to - 360	78
Stereoscopic PIV	800	Tumble	270, 225, 180, 135, 90, -90, -180, -270	600
	800	Swirl	270, 225, 180, 135, 90, -90, -180, -270	600
Tomographic PIV (4mm light sheet thickness)	800	Tumble	270, 225, 180, 135, 90, -90, -180, -270	600
	800	Swirl	270, 225, 180, 135, 90, -90, -180, -270	600

Data files

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Contributed by: Carl Philip Ding,Rene Honza, Elias Baum, Andreas Dreizler — Fachgebiet Reaktive Strömungen und Messtechnik (RSM),Technische Universität Darmstadt, Germany

Contributed by: Brian Peterson — School of Engineering, University of Edinburgh, Scotland UK

Contributed by: Chao He , Wibke Leudesdorff, Guido Kuenne, Benjamin Böhm, Amsini Sadiki, Johannes Janicka — Fachgebiet Energie und Kraftwerkstechnik (EKT), Technische Universität Darmstadt, Germany

Contributed by: Peter Janas, Andreas Kempf — Institut für Verbrennung und Gasdynamik (IVG), Lehrstuhl für Fluiddynamik, Universität Duisburg-Essen, Germany

Contributed by: Stefan Buhl, Christian Hasse — Fachgebiet Simulation reaktiver Thermo-Fluid Systeme (STFS), Technische Universität Darmstadt, Germany; former: Professur Numerische Thermofluiddynamik (NTFD), Technische Universität Bergakademie Freiberg, Germany

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© copyright ERCOFTAC 2018