Assessment of single-shot temperature measurements by thermally-assisted OH PLIF using excitation in the A2Σ+–X2Π (1-0) band

The present experimental work reports on the temperature measurements in a Bunsen flame, covered by a flat cooled plate from the top. The temperature field is measured based on the planar laser-induced fluorescence method for hydroxyl radical (OH) during the excitation of excitation Q1(8) line of the (1-0) band of the A2Σ+-X2Π electronic system. Thermometry was based on the imaging of the ratio of the fluorescence intensity for the band (2-0) and bands (0-0), (1-1). The paper presents the obtained temperature fields for the distances between the plate and the burner of 1, 2 and 3 calibres. The paper also concludes that the used method can be implemented using a single-pulse laser illumination and is effective for the detection of cold zones.

Section: Resultsmentioning

confidence: 99%

Temperature field measurements between a Bunsen flame and flat a cold plate by using PLIF

Tolstoguzov

Chikishev

2022

“…Figure 3 shows examples of the averaged fluorescence signal obtained from two cameras (for H/d = 1 and 2). The PLIF signal for the spectral range of 260-270 nm (left row) is noticeably weaker than that for 300-320 nm (right row), the processed images for the first case have a significantly lower signal-to-noise ratio, including due to the contribution from scattered laser radiation (this is discussed in detail in [8]). Taking into account the signal received from two cameras, the ratio of these signals to each other and calibration, averaged temperature fields for the selected distances were obtained.…”

Section: Resultsmentioning

confidence: 97%

“…The sample for each H/d ratio consisted of 500 images. To convert the ratio of fluorescence intensities to temperature, the calibration obtained for the Bunsen flame was used [8]. The image shows an estimate of the temperature of the combustion products in the range of 500-1500 K. In the initial images, the maximum intensity of the fluorescence signal is observed behind the flame front at the boundary of the outer mixing layer and the base of the swirling jet.…”

Section: Resultsmentioning

confidence: 99%

Temperature measurements in a swirling impinging flame by planar laser-induced fluorescence

Tolstoguzov

2021

This article presents the results of approbation of the method for registering temperature distributions based on the planar laser-induced fluorescence of a hydroxyl radical (OH) when the band (1-0) of the A2Σ+–X2Π system is excited. The thermometry is based on the recording the ratio of the radiation intensity of the band (2-0) and the bands (0-0), (1-1). Numerical modelling of fluorescence spectra is performed using the LASKIN program for the most frequent excitation lines Q2(7), Q1(8), R1(14), P1(2). The temperature field of a swirling flame, impinging on a flat cold surface, for H/d = 1, 2 and 3 calibres (where H is the distance between the jet nozzle and the surface, d is the outlet diameter of the nozzle) is obtained. The results of the work demonstrate that when the transition Q1(8) is excited, the ratio of the intensity of fluorescence signals for the band (2-0) and the bands (0-0), (1-1) provides a high sensitivity to temperature and is not significantly affected by fluorescence quenching. The report also concludes that this method can be implemented using single pulsed laser illumination and is effective for the detecting the position of flow recirculation zones and registering hot heat release zones with the combustion products.

“…A tunable dye laser excited OH fluorescence at the wavelength of the Q1(8) transition. Selection of the wavelength was conditioned by OH fluorescence measurements made for the same experimental setup under reacting flow conditions [21]. The average pulse energy at 283 nm was approximately 12 mJ.…”

Section: Figure 1 Scheme Of the Experimental Setupmentioning

confidence: 99%

Investigation of unsteady combustion of methane-air flame in a model combustion chamber with swirling flow

Lobasov

2021

The present paper reports on the investigation of unsteady combustion of a methane-air mixture, including combustion at increased pressure in the combustion chamber and increased temperature of mixture heating for a model gas-turbine swirl burner based on a design by Turbomeca. To measure the velocity and OH fluorescence fields in the flows a combination of stereoscopic PIV and acetone PLIF systems is used. In all cases, the flow dynamics is associated with the movement of large-scale vortex structures in the inner and outer mixing layers and the flow structure corresponds to a swirling jet with a central recirculation zone containing combustion products. An increase in the heating temperature of the mixture and pressure in the combustion chamber leads to a periodic partial separation of the flame from the model swirl nozzle. However, the flow of fuel through the central channel will stabilize the flame.