XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X The University of Sydney X X X X Department of Mechanical and Mechatronic Engineering X X >> << X X >> << X X >> and << X X >> << X X >> << X X Sandia National Laboratories X X X X Combustion Research Facility X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X X X Turbulent Nonpremixed Combustion Data X X X X for X X X X Piloted and Bluff-Body Stabilised Flows X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX IF YOU USE THE DATA PROVIDED HERE PLEASE E-MAIL YOUR NAME, AFFILIATION AND E-MAIL ADDRESS TO A.R. MASRI. WE WILL THEN KEEP YOU INFORMED OF ANY UPDATES OR ADDITIONS TO THE DATABASE A.R Masri Department of Mechanical and Mechatronic Engineering The University of Sydney NSW, 2006 Australia Tel: (61) 2 9351 2288 FAX: (61) 2 9351 7060 Email: masri@mech.eng.usyd.edu.au http://www.mech.eng.usyd.edu.au/research/energy/#data XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX DISCLAIMER No responsibility is assumed by the suppliers of these data for any injury and/or property damage as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas based on these data. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX REFERENCING To reference these data use: Combustion data base, The University of Sydney and The Combustion Research Facility, Sandia National Laboratories, http://www.mech.eng.usyd.edu.au/research/energy/#data XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 September, 1997 Release 2.0 A comprehensive set of data collected in bluff-body stabilised flames and nonreacting jets is released. Measurements of flow, mixing, temperature as well as composition fields are presented. The composition field measurements include species such as CO, CO2, H2, H2O, O2, N2, Hydrocarbon, as well as OH and NO. These measurements complement data on pilot-stabilised flames which have been available on this web site since 1995. If you are interested in the pilot-stabilised flame data, you should read the file: Piloted If you are interested in the bluff-body stabilised flame data, you should read the file: Bluffbd ========================================================================== CNG and LPG fuels ----------------- A volumetric composition is given for these fuel mixtures which are used extensively CNG: 90.9% CH4, 5.0% C2H6, 1.1%C3H8, 2.4%CO2, balance:C4H10 and N2 LPG: 94.1% C3H8, 5.5% C3H6, 0.4% C4H10 Velocity Measurements --------------------- Two colour LDV system with frequency shifted beams are used to measure the horizontal and vertical velocity components. The fuel and the air are seeded in order to reduce the seeding bias. Uncertainties of the LDV technique are mainly associated with the seeding bias due to steep temperature gradients and the presence of more than one particle in the probe volume. The error due to seeding bias is very hard to quantify and is believed to be small, however, the error due to the presence of more than one particle in the measurement volume is believed to be 4% for the mean and 7% for the rms fluctuations. The flowfield data are collected at the University of Sydney and consist of radial profiles of mean and rms of fluctuations of the axial and radial velocity components at a range of axial locations. The flowfield data are provided for selected jets and flames only. Temperature and composition Measurements ---------------------------------------- Temperature and composition data are instantaneous measurements collected at the Combustion Research Facility, Sandia National Laboratories, Livermore CA. Measurements have been made using the Raman/Rayleigh/LIF technique to give instantaneous and simultaneous temperature and the concentration of many species at a single point in the flame. The species measured are: N2, O2, CH4 (or CH3OH), CO, CO2, H2, H2O. Other species such as OH and NO are measured for selected flames only. A range of fuel mixtures and flame velocities ranging from low to close to extinction have been studied. The following details give useful information about the processing and tabulation of the temperature and composition data: 1/ Each data file contains information about the axial and radial measurement location. 2/ The mixture fraction is obtained using the Bilger formula (Combust. Flame 80:135-149 (1990)) which is given by: 2(Zc -Zc,o) + (Zh-Zh,o) - (Zo-Zo,o) ----------- --------- --------- Wc 2Wh Wo zi = ------------------------------------------ 2(Zc,f -Zc,o) + (Zh,f-Zh,o) - (Zo,f-Zo,o) ------------- ----------- ----------- Wc 2Wh Wo where Z(i) is a conserved scalar given by the total mass fraction of element (i), and Wi is the molecular weight of elements (carbon, c, hydrogen, h and oxygen, o). Subscripts (f) and (o) refer to the fuel and air streams, respectively. Note: Values of Zo,o; Zh,o; Zc,o; Zo,f; Zh,f; and Zc,f used to calculate zi are given for each fuel in the (*.dat) file in the relevant directory. 3/ Mixture fraction ranges from zero to one. Negative values of mixture fraction which may arise due to differential diffusion are not allowed. Users interested in differential diffusion effects can redefine and re-calculate their mixture fraction from the tabulated mass fractions. 4/ The argon contained in air is not accounted for and its mass fraction is lumped with that of nitrogen. 5/ Each file contains Favre and ensemble mean and rms fluctuations for the data points contained in the file. 6/ Temperature is obtained either from the Rayleigh signal or from the sum of the species number densities (assuming a mixture of ideal gases). 7/ The percentage mass fraction of species (Y(i)*100) is tabulated except for NO where the percentage mass fraction*100 (Y(NO)*10000)) is given. If the mass fraction of a species is zero for the entire data set in a given directory it means that the species have not been measured. Symbol h-c refers to the parent hydrocarbon fuel (CH4, CH3OH, etc...) 8/ The factor TNDR is defined as: TNDR = sum of species number densities measured from Raman and LIF over the total number density obtained from the Rayleigh temperature, or equivalently: TNDR = Temp. from Rayleigh / Temp. from sum of species number densities. TNDR = 0.0 implies that temperature is obtained from the sum of species number densities. Otherwise temperature is obtained from Rayleigh. Generally, temperature is obtained from the Rayleigh measurements except in cases where we suspect that the Rayleigh signal is corrupted by Mie scattering. This is the case, for example, in flames of methanol where there may be scattering from fine droplets. Also, measuring in regions of the flames where there are solid particles or soot particles corrupt the Rayleigh signals. 9/ All the measured mass fractions are normalised such that the sum of the tabulated mass fractions equals one. 10/When the Rayleigh temperature is used (the factor TNDR is not equal to zero) the original measured, non-normalised species mass fractions may be recovered from the tabulated data as follows: Y(i, original) = TNDR * Y(i, normalised, tabulated) where i corresponds to any of the tabulated species. 11/Departure of the total mass fraction of the measured species from unity is only partly due to the fact that not all species existing in the probe volume are being measured. There are random and systematic sources of error on the measured signals leading to differences between the temperature obtained from Rayleigh and that obtained from the sum of species number densities. A later section on Accuracy Considerations gives more details about these errors. In cases where the TNDR factor varies significantly from 1.0 the following guidelines are given: TNDR > 1.0 ---------- This generally implies that the species mass fractions are affected by error which remains uncorrected for and which may be due to various interference This leads to artificially high concentrations and hence a lower temperature from the sum of species number densities. An estimate of this error on each species is extremely difficult to quantify but a guide to the expected error is given later in the section on Accuracy Considerations. TNDR < 1.0 ---------- This generally implies that the Rayleigh signal is subject to interference due to Mie scattering leading to artificially lower Rayleigh temperatures and hence a lower value of TNDR. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX A description of the burners, the initial and boundary conditions and the experimental errors are given in the following files: Piloted: for the pilot-stabilsied jet flames Bluffbd: for the bluff-body stabilsied jets and flames XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Accuracy Considerations ----------------------- There are a number of sources of error that have to be considered in evaluating the overall accuracy of laser-based, instantaneous measurements of species concentrations in flames. Only sources of error which may be influencing the data are mentioned here: (i)photon noise, (ii)interference error and (iii)spatial resolution. Photon noise is associated with the number of photons, n collected by a given detector at each laser pulse and it decreases proportionally to 1/(n^0.5). This noise is expected to become significant at species mole fractions less than a few percent. The interference error depends on the magnitude of the fluorescence or chemiluminescence interference with the measured species. The error due to spatial resolution is not considered to be substantial and is discussed further below. Other sources of error which are particular to the Raman system discussed here are (i)calibration drift due to the changes in laser lineshape over the lifetime of the dye, (ii)shot-to-shot variation in laser lineshape, and (iii)uncertainties in the temperature dependent bandwidth calibration factor f(T), especially for intermediate temperatures. The signal to noise ratio (S/N) gives a measure of the combined shot-to-shot random errors which are primarily due to photon statistics. It should be noted that, for scalar measurements in uniform steady flows and flames, the ratio of the rms fluctuations to the mean is given by the inverse of the S/N ratio. A measure of the S/N ratio can be obtained from the calibration data since these measurements are made in a uniform field of known temperature and species concentration. The reacting and nonreacting calibration data may be used here giving the variation of the S/N over a range of temperatures and species concentrations. Estimates of the S/N ratios obtained during experiments conducted between 1984 and 1992 are given in file stn92.dat. Since then the Raman-Rayleigh system has been improved by using better lasers and detectors. Estimates of the S/N ratios obtained during experiments conducted in 1995 are given in file stn95.dat. S/N ratios are given for typical data samples. The results are tabulated versus temperature for the Rayleigh signal and versus species number density (molecules/cm^3) for the Raman signals. S/N ratios for data collected 1992 and before stn92.dat (main directory) S/N ratios for data collected 1995 and after stn95.dat (main directory) The general trend for the signal to noise ratios presented in stn*.dat is to increase with number density. A correlation of the form S/N = A_i * [i]^0.5 produces an adequate fit for all the scalars shown in stn*.dat. Here A_i is a constant and [i] is the number density of species. This square root dependence on the number density implies that photon statistics is a major contributor to noise on all of the Raman signals. Table 1 shows estimates of the percentage errors on various species for two typical samples collected in a CH4/H2 flame using the experimental setup. Lean and rich sample compositions are obtained from the actual data and are taken here as illustrations of typical measurement conditions. It is evident that the improvements made in 1995 have led to a significant reduction in the percentage error on all scalars. The percentage error increases with decreasing number density or mole fraction. It should be emphasised that the errors reported here do not include the effect of interferences and spatial resolution. Raman interferences affect only selected species and are believed to have a small contribution to the overall error. The fluorescence interference from soot precursors (mainly in the rich side of the flame) is very low in these flames and that improves the signal to noise ratio in all the affected Raman signals. Flames with high hydrocarbon fuels are most affected and among the Raman signals the CO line suffers the highest interference levels. ---------------------------------------------------------------------------- Table 1 Estimates of percentage error on typical samples of data collected collected in a turbulent methane-hydrogen flame. ---------------------------------------------------------------------------- Sample Temperature Species % Mass Number %Error %Error Fraction Density 1992 1995 or Before or After ---------------------------------------------------------------------------- Lean 1900 CH4 0.0 0.0 - - O2 4.0 0.12E18 17.0 10.0 N2 75.0 2.63E18 5.0 0.8 CO2 8.0 0.18E18 11.1 4.5 CO 2.0 0.07E18 16.6 9.0 H2 0.5 0.23E18 17.0 12.5 H2O 11.0 0.60E18 7.1 5.0 Rich 1400 CH4 18.0 1.09E18 10.0 2.3 O2 0.0 0.0 - - N2 57.0 1.98E18 6.3 1.1 CO2 5.5 0.12E18 12.0 5.5 CO 5.5 0.19E18 10.0 8.3 H2 2.5 1.22E18 6.9 4.0 H2O 12.0 0.65E18 7.2 4.0 ---------------------------------------------------------------------------- Spatial Resolution ------------------ Spatial resolution issues for these data are discussed elsewhere [12]. The length of the measurement probe is 1mm and the diameter is about 0.6mm. Typical Kolmogorov length scales in the flame investigated range from 30 to 150 microns. Using estimates of the length scales, it is found that the spatial resolution error ranges from 3% to 16% depending on the axial location in the flame and on the jet velocity. More information about spatial resolution effects may be found in Mansour, M.S. et al. (Combust. Flame 82:411 (1990)). -------------------------------------------------------------------------- Here is a list of references which may be used for further information. Reference 12 reviews both the piloted and bluff-body stabilised flame data and should be consulted first. Only part of the data availble on this web site are published in these references 1 Masri, A.R. and Bilger, R.W., `Turbulent Diffusion Flames of Hydrocarbon Fuels Stabilised on a Bluff Body', Twentieth Symposium (International) on Combustion. The Combustion Institute, Pittsburgh, 1985, pp. 319-326. 2 Dibble, R.W., Masri, A.R. and Bilger, R.W., `The Spontaneous Raman Scattering Technique Applied to Nonpremixed Flames of Methane', Combust. Flame 67:189-206 (1987). 3 Masri, A.R. and Bilger, R.W., `Turbulent Nonpremixed Flames of Hydrocarbon Fuels Near Extinction: Mean Structure from Probe Measurements', Twenty-first Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1988, pp. 1511-5120. 4 Masri, A.R., Dibble, R.W. and Bilger, R.W., `Turbulent Nonpremixed Flames of Methane Near Extinction: Mean Structure from Raman Measurements', Combust. Flame 71:245-266 (1988). 5 Masri, A.R., Bilger, R.W. and Dibble, R.W., `Turbulent Nonpremixed Flames of Methane Near Extinction: Probability Density Functions', Combust. Flame 73:261-285 (1988). 6 Masri, A.R., Bilger, R.W. and Dibble, R.W., `Conditional Probability Density Functions Measured in Turbulent Nonpremixed Flames of Methane Near Extinction', Combust. Flame 74:267-284 (1988). 7 Masri, A.R., Bilger, R.W. and Dibble, R.W., `The Local Structure of Turbulent Nonpremixed Flames Near Extinction', Combust. Flame 81:260-276 (1990). 8 Masri, A.R., Dibble, R.W. and Barlow, R.S., `The Structure of Turbulent Nonpremixed Flames of Methanol over a Range of Mixing Rates', Combust. Flame 89:167-185 (1992). 9 Masri, A.R., Dibble, R.W. and Barlow, R.S., `Chemical Kinetic Effects in Nonpremixed Flames of $H_{2}/CO_{2}$ Fuel', Combust. Flame 91:285-309 (1992). 10 Masri, A.R., Dibble, R.W. and Barlow, R.S., `Raman-Rayleigh Measurements in Bluff Body Stabilised Flames of Hydrocarbon Fuels', Twenty-fourth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1992, pp. 317-324. 11 Masri, A.R., Dally, B.B., Barlow, R.S. and Carter, C.D., `The Structure of The Recirculation Zone of a Bluff-Body Combustor', Twenty-fifth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1994, pp.1301-1308. 12 Masri, A.R., Dibble, R.W., and Barlow, R.S., `The Structure of Turbulent Nonpremixed Flames Revealed by Raman-Rayleigh-LIF Measurements', Prog. Energy Combust. Sci., 22:307-362 (1997). 13 Dally, B.B, Masri, A.R., Barlow, R.S., Fiechtner, G.J., and Fletcher, D.F., `Measurements of NO in Turbulent Nonpremixed Flames Stabilised on a Bluff Body', Twenty-sixth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1996, Vol. 2, pp.2191-2197. 14 Dally, B.B, Masri, A.R., Barlow, R.S., Fiechtner, G.J., and Fletcher, D.F., 'Instantaneous and Mean Compositional Structure of Bluff-Body Stabilised Nonpremixed Flames', Combust. Flame 114:119-148 (1998). 15 Dally, B.B, D.F. Fletcher, and Masri, A.R., 'Flow and Mixing Fields of Turbulent Bluff-Body Jets and Flames', Combustion Theory and Modeling 2:193-219 (1998).