=Paper=
{{Paper
|id=Vol-452/paper-21
|storemode=property
|title=Probing the heat during the PCCI beat: Determining PCCI engine temperatures using two-line thermometry
|pdfUrl=https://ceur-ws.org/Vol-452/poster1.pdf
|volume=Vol-452
}}
==Probing the heat during the PCCI beat: Determining PCCI engine temperatures using two-line thermometry==
https://ceur-ws.org/Vol-452/poster1.pdf
Probing the heat during the PCCI beat:
Determining PCCI engine temperatures using two-line thermometry
1* 1** 1 1 1 1
J.R. Mannekutla , J.C.C.M. Huijben , A.J. Donkerbroek , A.P. van Vliet , L. Gerritsen , N.J. Dam and
1
J.J. ter Meulen
1
Applied Molecular Physics, Inst. for Molecules and Materials, Radboud University Nijmegen
*j.mannekutla@science.ru.nl, **jhuijben@science.ru.nl
Temperature is a key parameter for reaction progress during combustion, and as such its experimental determination
has been a subject of considerable interest for many years. The aim of our present project is to study the 2-D tem-
perature field in a realistic heavy-duty Diesel engine under the conditions of premixed charge compression ignition
(PCCI) combustion. Two-line OH Laser Induced Fluorescence (LIF) thermometry will be used, in combination with
spontaneous Raman scattering as an independent calibration. Here, we discuss the initial test measurements per-
formed on a high-pressure high-temperature gas cell, and the selection of OH line pairs for thermometry. In addition,
we will discuss Raman scattering temperature measurements that were carried out in a realistic engine.
Introduction Experiment and Results
Over the years, laser diagnostics is widely used In our first approach using LIF, temperatures
in combustion science, research and development can be obtained by performing excitation scans,
to investigate transient phenomena without influ- whereby the laser is tuned across a series of ab-
encing the system under study by inserting probes sorption lines thereby probing the ground state
[1]
and surfaces . Laser-induced fluorescence (LIF) rotational population distribution. For a pair of lines
is frequently used for remote detection of concen- (two-line LIF), the relative ground state populations
tration and temperature. Due to the relatively can be determined and related to temperature via
strong signals, high spatial and temporal resolution the Boltzmann distribution. To this end several
can be achieved. Within the duration of a single aspects, like Vibrational Energy Transfer (VET),
laser pulse (typically a few nanoseconds) volume Rotational Energy Transfer (RET), electronic
elements in the sub-millimetre range can be ob- quenching and absorption coefficients have to be
served. With illumination by laser light sheets ex- taken into account. In addition, criteria for the se-
tended two-dimensional cross-sections through the lection of the set of peaks have to be included.
process under study can be excited and resulting First, the lines need to be isolated so that even at
signal light can be imaged on the chip of a CCD high pressures no overlap with neighboring peaks
(charge-coupled device) camera. Because imaging is present. Preferably, the two transitions should
techniques require strong signals, laser-induced go to the same upper state to avoid errors due to
fluorescence is most frequently used for this pur- differences in quenching. Finally the ground state
pose. rotational number N ' ' of the involved transitions
Apart from LIF, linear or spontaneous Raman [3]
should be between 2 and 13 .
scattering provides a number of advantages for the The two-line LIF method is still under investiga-
diagnostics of combustion flames: it offers good tion. To test our method of temperature analysis,
spatial resolution; all molecular species with local an optically accessible high-pressure cell in which
abundances larger than 10 ppm can, in principle, temperatures of 1100 K and pressures of 5 MPa
[2]
be probed ; the relation between observed inten- can be reached has been installed. In the cell,
sities and local molecular densities is linear, greatly thermal dissociation of water vapor takes place
simplifying abundance calibration by a single com- thereby creating OH radicals. Using a thermo-
parison to a known reference; and it covers a wide couple, placed into the cell as a reference, estima-
spectral range including the fingerprint of many tions of temperature errors of the two-line LIF me-
molecular species using the same instrument with- thod can be determined and further investigated.
in the same experiment, employing just one single Currently the Q2(10) and Q1(11) lines, which have
laser at a fixed excitation frequency. almost the same upper state, are under investiga-
In our present work, we have used both LIF tion. These lines have been observed in the test
and spontaneous Raman scattering approaches cell for pressures up to 0.5 MPa. An example of a
for the quantitative local temperature field mea- spectrum for lower pressure (0.17 MPa) is given
surements both in a high pressure cell and in a below (figure 1).
realistic diesel engine, respectively.
6
x 10
Experimental
2.5 P1(6) Simulation
P2(5)
P12(5)
2
Q2(10)
Q1(11)
1.5
Intensity
O12(4)
1
0.5
284.4 284.45 284.5 284.55 284.6 284.65 284.7 284.75 284.8 284.85 284.9
(nm)
Figure 1: Q2(10) and Q1(11) lines observed in the test cell (P=0.17 Mpa, T=1064K).
In second approach, we have applied sponta- For different CA‘s, the measured quasi-local
neous Raman Scattering technique for quantitative temperatures from the Raman spectra and the
temperature measurements in an optically access- global temperature derived from pressure curves
ible six-cylinder, heavy duty research engine for are compared and also shown in figure 3. An
o
crank angles (CA) up to 30 (BTDC and ATDC). agreement of the temperature measurements us-
All our measurements have been performed us- ing Raman and that obtained from the pressure
o
ing one cylinder of a heavy-duty Diesel engine curves is seen clearly up to 30 CA. Further, we
(DAF Trucks, NL). A description of our optical re- have observed a large discrepancy of temperature
search engine has been summarized in Ref [4]. An measurements from Raman scattering after 30
o
excitation wavelength of 532 nm was used to avoid CA (not shown in the figure). This could be due to
fluorescence from trace lubricants and fuel com- the weak local strength of anti-Stokes signal which
o
pounds inside the engine. The Stokes and anti- is difficult to observe after 30 CA.
Stokes spectra were recorded for compressed air 900
Raman scattering
Pressure curver
without combustion. In addition, the fuel injector
was also lifted to reduce elastic scattering from its
tip. An averaged anti-Stokes and Stokes spectrum 750
measured at top dead centre (TDC) is shown in
figure 2. The temperature obtained from the signal
ratio of these two is shown in figure 3. 600
Temperature (K)
o
450
607.648
T=903 ± 77 K
220000
300
-50 -40 -30 -20 -10 0 10 20 30 40 50
Stokes
CA
165000
Intensity
Figure 3: Comparison of Temperatures derived from
110000
Raman spectra and the pressure curves.
481.066
Anti-stokes
55000 References
473.502
467.861
[1] C. Schulz and V. Sick, Tracer-LIF diagnostics: quanti-
476.205
tative measurement of fuel concentration, tempera-
0
480 520 560 600 ture and fuel/air ratio in practical combustion systems,
Wavelength (nm) Progress in Energy and Combustion Science 31,
Figure 2: Averaged Raman spectrum measured at TDC.
75–121 (2005).
The resulting calculated temperature is 903±77K.
[2] G. Tejeda, J.M. Fernandez-Sanchez and S. Montero,
High-performance dual Raman spectrometer,” Appl.
Spectrosc. 51, 265–276 (1997).
[3] Devillers, R., Bruneaux, G., Schultz, C., Development
of a two-line OH-laser-induced fluorescence thermo-
metry diagnostics strategy for gas-phase temperature
measurements in an engine, Applied Optics 47,
5871-5885 (2008).
[4] K. Verbiezen, R.J.H. Klein-Douwel, A.J. Donkerbroek,
A.P. van Vliet, W.L. Meertz, N.J. Dam and J.J. ter
Meulen, Attenuation corrections for in-cylinder NO
LIF measurements in a heavy-duty Diesel engine,
Appl. Phys. B 83, 155–166 (2006).