Test Data AC2-10
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.
| 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 (pin,1, pin,2, and pout) 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).
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| 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.
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| 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]. |
| 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 | |
| 1500 | Tumble | 270, 225, 180, 135, 90 | 400 | |
| 1500 | Swirl | 270, 180, 90 | 400 | |
| Tomographic PIV (8mm light sheet thickness) | 800 | Tumble | 270, 225, 180, 135, 90 | 600 |
| 1500 | Tumble | 270, 90 | 400 |
Description of the experiment
Particle image velocimetry (PIV) was used to capture the flow field within the central tumble plane. The in-cylinder flow was measured by conventional planar particle image velocimetry (PIV), stereo-PIV, high-speed PIV, and tomographic PIV. Silicone oil droplets (∼ 1μm diameter) were used for seeding the intake flow. Further details on the setup are provided in [1, 2].
Conventional PIV and stereo-PIV
Conventional 10Hz PIV was applied for the statistically independent sampled data to achieve highest possible quality and resolution. A dual cavity Nd:YAG laser (Gemini New wave) was used for illumination and a double frame CCD camera (PCO SensiCam, 1376$\times$1040\,pixels, 12\,bit) to detect the scattered light of the seeding particles. Measurements were performed with a resolution of 2.2\,mm and 0.6\,mm based on a 32$\times$32\,pixel interrogation window resolving the global in-cylinder flow (FOV = 65$\times$65\,$\mathrm{mm^{2}}$) and the small scales (FOV = 20$\times$15\,$\mathrm{mm^{2}}$). The conventional setup provides the two in-plane velocity components (2D2C). With the addition of another CCD camera in a stereo setup all three velocity components were captured in the plane (2D3C). \
Uncertainties
Data files
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
© copyright ERCOFTAC 2018