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Combustion & Laser Sensing Laboratory
仪器设备
Laser-induced incandescent (LII)
Introduction
Laser-induced incandescence (LII) soot measurement system refers to the generation of quasi-black body radiation after high-energy laser beams heat soot particles to 4000K. By analyzing the radiation signal captured by the high-speed camera, information such as the concentration of soot and the primary particle size of soot can be obtained.
Components
Nd-YAG Laser, high-speed camera (Princeton instruments PIMAX 4 ICCD), Optical components (lens, iris, beam splitter, etc.), automatic linear stage, counterflow diffuse flame burner .
Features
The LII system has simple principles, low flame interference, strong signal, and high signal-to-noise ratio. As a more advanced non-contact optical diagnostic technology, it can obtain the two-dimensional spatial distribution of the instantaneous soot concentration in the thin layer of laser light irradiation . Moreover, in combination with other optical diagnostic techniques (such as LIF), information about intermediate products and soot precursors of the combustion process can also be obtained.
Tunable diode laser absorption spectroscopy(TDLAS)
Introduction
TDLAS (Tunable Diode Laser Absorption Spectroscopy) mainly uses the narrow linewidth and wavelength of a tunable semiconductor laser that changes with the injection current. By modulating the wavelength of the laser, the wavelength of the laser scans the absorption peak of the gas molecule under test. Lambert-Beer's law makes the gas molecules absorb the modulated laser, and combines the tomography algorithm to reconstruct the spatial distribution of flame flow field parameters such as flame temperature and component concentration from the absorbance.
Components
Photodetector (Thorlabs, PDA 10PT-EC1.0-5.8 µm, PDA20CS2 800-1700nm), free space bias detector (DET100A2), optical components (Lens, reflector, iris, etc.), automatic linear stage, laminar premixed McKenna burner.
Features
TDLAS technology has the advantages of high sensitivity, high stability, high response speed, and no interference in in-situ measurement. It can realize gas molecule concentration detection in various complex and harsh environments.
Diffuse back-imaging system (DBI)
Introduction
DBI system is a path integral technique. For axisymmetric flames, the true distribution of the soot concentration in the two-dimensional field can be obtained by measuring the cumulative signal intensity in the line of sight before and after the diffused light passes through the flame and combining with the tomographic inversion algorithm.
Components
Quartz Tungsten Halogen Lamp (Newport, QTH6333), scientific camera (Andor Zyla 4.2 Plus), optical components(Lens, integrating sphere, diaphragm, etc.), automatic linear stage, counterflow diffuse flame burner .
Features
Compared with the traditional single-point scanning extinction method, the DBI has higher time and space resolution, the system is easy to build, and the experiment operation is simple. It can be used for the measurement of the non-steady flame for soot concentration.
Fourier transform infrared spectrometer
Introduction
The Michelson interferometer is used to obtain the absorption spectrum information, and the time domain function interferogram is transformed into the frequency domain function diagram through Fourier mathematical transformation. Through the micro-probe flame sampling, combined with the long optical path gas cell, the composition and concentration of the intermediate gas products in the combustion process can be measured. Combined with a thermogravimetric analyzer, it can measure the composition and concentration of the decomposition products of biomass, soot and other solid reactants.
Components
FTIR (BRUKER-INVENIO-R), thermogravimetric analyzer (TGA-IR), synchronous thermal analyzer (STA 2500 Regulus)
Features
The FTIR-TGA combined system can achieve rapid measurement with high chemical specificity. It can characterize substances through functional groups and is suitable for online analysis of substances with moderate to strong infrared absorption.
Gas chromatography mass spectrometry
Introduction
Gas Chromatography (GC, Gas Chromatography) is an experimental technique that separates a mixture into individual components. It is used to identify and quantify sample components. After the gas to be measured enters the chromatographic column, the components of the mixture can be separated according to the adsorption capacity of the adsorbent for each component. Combining with mass spectrometry (MS, Mass Spectrometry), FID, TCD and other detectors can achieve qualitative and quantitative combustion intermediate products analyze.
Components
Gas-Chromatography (7890B), Mass-Spectrometry (5977), fusedquart microprobe (Agilent PN: 160-2625-5), particulate filter (Valco PN: SS-4TF-2), heating belt (Omega PN FGR-060) /240V), counterflow diffuse flame burner.
Features
The GC-MS combined system has better MS resolution and lower mass deviation, as well as superior sensitivity and spectrum integrity. Automated spectral deconvolution, identification and quantification software simplifies post-run analysis. .
Time-resolved PIV
Introduction
The high-frequency particle tracing velocity measurement system disperses the tracing particles in the flow field, and uses a pulsed laser light source to enter the measured flow field area. Through two or more consecutive exposures, the image of the particles is recorded by a CCD camera.
Components
Nd-YLF double pulse laser, high-speed camera (Phantom Miro LAB 320), Optical components (reflectors, cylindrical mirrors, etc.), automatic linear stage, counterflow diffuse flame burner.
Features
The high-frequency particle tracing velocimetry system (PIV) is a non-contact measurement method. The overall structure and transient images displayed by the plane flow field can record the relevant information of the entire flow field at the same time, and can respectively give the average speed, pulsation speed and strain rate.
Introduction
The SMPS system includes three parts: Electrostatic Classifier (EC), Condensation Particle Counter (CPC), and Differential Mobility Analyzer(DMA). The inhaled soot particles first pass through the electrostatic classifier EC, the size of the soot particles is classified by the EC, and then the soot particles enter the particle counter CPC, and the classified particles are counted by the CPC to obtain the soot Data such as particle size distribution and number density.
Components
Electrostatic classifier EC (TSI 3082), condensation particle counter CPC (TSI 3750), nanointensifier (TSI 3757), differential electric mobility analyzer DMA (TSI 3086).
Features
The SMPS system combines the traditional advantages of TSI in particle classification and counting, and adopts a new technology capable of measuring particles smaller than 1 nanometer. It can measure particle size and number concentration with high resolution and high speed, and monitor engineering and The reaction kinetics of aerosol particles and the generation of new particles. It can be used in nanotechnology research and material synthesis, atmospheric research and environmental testing, combustion and engine emissions research, indoor air quality measurement and many other fields.
Laser-Induced Fluorescence (LIF)
Introduction
The components (radicals) in the flame will transition from the electronic ground state to the electronic excited state after absorbing the ultraviolet rays provided by the dye laser, and the excited components (radicals) will emit fluorescence when they return to the ground state. The fluorescence intensity is positively correlated with the component (radical) concentration.
Components
High resolution nanosecond dye laser (Q-scan), wavelength range 200nm-4.5µm
Features
Ultra-high precision mechanics ensure extreme wavelength accuracy and makes this laser ideal for combustion and high resolution spectroscopy applications. The Q-scan’s exceptional linearity (< 2 pm) ensures highest wavelength accuracy during scan. Quick change, "Plug & Play" dye cells and integrated look-up tables for non linear crystals means that wide wavelength scans are quick and easy.
Phase Doppler Particle-Size Analyzer (PDPA)
Introduction
The phase Doppler method is based on the principle of light scattering interference, which can complete the measurement of the flow velocity and particle size distribution of the tracer particles in a small, non-destructive optical probe measurement area defined by the intersection area of the two laser beams. When the particle passes through the measurement area of the probe, it scatters the light in the beam into a multi-detector receiving probe located at an off-axis acquisition angle. The phase shift between the Doppler pulse signals from different detectors is proportional to the size of the spherical particles.
Components
PowerSight Solid State Laser (TSI), Laser Doppler Velocity (LDV) system .
Features
The phase Doppler particle analyzer system (TSI) can provide accurate and reliable flow rate and particle size data in various measurement situations from simple fluids to high-speed and low-signal-to-noise ratio fluids. The system has up to 800MHz sampling rate and photon counting level sensitivity.
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