Bubble dynamics and atomization of acoustically levitated diesel and biodiesel droplets using femtosecond laser pulses.

This study focuses on the bubble dynamics and associated breakup of individual droplets of diesel and biodiesel under the influence of femtosecond laser pulses. The bubble dynamics were examined by suspending the droplets in the air through an acoustically levitated setup. The laser pulse energies ranged from 25 to 1050 µJ, and droplet diameters varied between 0.25 and 1.5 mm. High-speed shadowgraphy was employed to examine the influence of femtosecond laser intensity and multiple laser pulses on various spatial-temporal parameters. Four distinct sequences of regimes have been identified, depending on early and late times: bubble creation by individual laser pulses, coalescence, bubble rupture and expansion, and droplet fragmentation. At all laser intensities, early-time dynamics showed only bubble generation, while specifically at higher intensities, late-time dynamics revealed droplet breaking. The droplet breakup is further categorized into three mechanisms: steady sheet collapse, unstable sheet breakup, and catastrophic breakup, all following a well-known ligament and secondary breakup process. The study reveals that laser pulses with high repetition rates and moderate laser energy were the optimal choice for precise bubble control and cutting.

Simultaneous imaging of CH*, C2∗, and temperature in flames using a DSLR camera and structured illumination.

Measurement of chemical species and temperature mapping in flames is essential to understanding the combustion process. Multiple cameras are conventionally employed for measurement in such scenarios making the experimental setup not only cost-intensive but also challenging. To circumvent this, structured illumination (SI)-based methods are reported for multispecies chemiluminescence (CL) imaging using a single camera. In this paper, we demonstrate four-channel SI-based imaging for simultaneous snapshot C H ∗ and C2∗ CL imaging and two-color pyrometry for temperature profiles in a butane diffusion flame. We demonstrate our approach using individual species and multiple species imaging. Taking the advantage of the axisymmetric nature of the flame, the Abel transform is performed on the line-of-sight averaged images to obtain deconvoluted images. The deconvoluted maps of temperature are compared with the temperature data obtained by using a physical thermocouple probe.

Application of FRAME for Simultaneous LIF and LII Imaging in Sooting Flames Using a Single Camera.

In this article, the application of the FRAME (Frequency Recognition Algorithm for Multiple Exposures) technique is presented for multi-species measurements in symmetric and asymmetric ethylene/air diffusion flames. Laminar Bunsen-type and swirled diffusion flames are investigated to gain a better understanding of sooting combustion. For this purpose, simultaneous imaging is conducted in terms of Laser-Induced Fluorescence (LIF) of Polycyclic Aromatic Hydrocarbons (PAH) and Laser-Induced Incandescence (LII) of soot particles. Subsequently, the approach is utilized for simultaneous imaging of hydroxyl (OH)-LIF and soot-LII. Here, the modulated LIF- and LII-signals are acquired together as a single sub-image-with a single exposure utilizing the full sensor size of a single camera. By employing the frequency-recognition algorithm on the single image, the LIF- and LII-signals are spectrally isolated-generating two individual LIF- and LII-images. The flame luminosity and out-of-focus light such as reflected surrounding laser light are detected as non-modulated signals in the unprocessed image. These unwanted signals are suppressed using the image post-processing, and, therefore, the image contrast of the two resulting images is improved. It is found that PAHs mainly exist in the inner region near the burner and are surrounded by soot. The majority of the OH is distributed on the outer edges of the flame-representing the reaction zone and soot-oxidation region of the flame.

Statistical evaluation of nutritional components impacting phycocyanin production in Synechocystis SP

Alkaliphilic cyanobacterial cultures were isolated from Lonar lake (MS, India). Among the set of cultures, Synechocystis sp, was studied for phycocyanin production. A maximum yield was obtained in BG-11 medium at optimized conditions (pH 10 and 16 h light). In order to increase the phycocyanin yield media optimization based on the eight media components a Plackett-Burman design of the 12 experimental trials was used. As per the analysis CaCl2.2H2O and Na2CO3 have been found to be the most influencing media components at 95% significance. Further the optimum concentrations of these components were estimated following a Box Wilson Central Composite Design (CCD) with four star points and five replicates at the center points for each of two factors was adopted for optimization of these two media components. The results indicated that there was an interlinked influence of CaCl2.2H2O and Na2CO3 on 98% significance. The maximum yield of phycocyanin (12% of dry wt) could be obtained at 0.058 g/l and 0.115 g/l of CaCl2.2H2O and Na2CO3, respectively.

Statistical evaluation of nutritional components impacting phycocyanin production Synechocystis SP.

Alkaliphilic cyanobacterial cultures were isolated from Lonar lake (MS, India). Among the set of cultures, Synechocystis sp, was studied for phycocyanin production. A maximum yield was obtained in BG-11 medium at optimized conditions (pH 10 and 16 h light). In order to increase the phycocyanin yield media optimization based on the eight media components a Plackett-Burman design of the 12 experimental trials was used. As per the analysis CaCl2, 2H2O and Na2CO3 have been found to be the most influencing media components at 95% significance. Further the optimum concentrations of these components were estimated following a Box Wilson Central Composite Design (CCD) with four star points and five replicates at the center points for each of two factors was adopted for optimization of these two media components. The results indicated that there was an interlinked influence of CaCl2, 2H2O and Na2CO3 on 98% significance. The maximum yield of phycocyanin (12% of dry wt) could be obtained at 0.058 g/l and 0.115 g/l of CaCl2, 2H2O and Na2CO3, respectively.