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The effective use of marine biomass has recently been identified as a feasible method of renewable energy production. Therefore, to facilitate the effective use of algae biomass, it is essential to develop techniques for the mass production of algal cultures. It is also important to develop artificial culture techniques that are not affected by natural phenomena such as weather. This study utilized a newly developed culture technology that uses seawater with high concentrations of dissolved CO2(CO2seawater). The experiments in this study were conducted to test the effects of CO2seawater on algal growth. In addition to experimental conditions that were previously investigated in industrial algae farming scenarios, it is also necessary to consider the effects of new parameters associated with increased CO2concentrations. The following four conditions were experimentally investigated: (1) the tolerance of algae to changes in pH, (2) the effect of CO2seawater on long-term culture growth, (3) the effect of continuous culture experiments, and (4) the effect of water flow rate on cultured algae. The results in terms of having excelled especially indicate that a 1-month long-term algae culture period in seawater with CO2concentration of 1.0% led to growth that was approximately 4.5 times faster than growth in seawater without the CO2additive. Furthermore, the results also provided useful information regarding the proper flow rate needed to enhance algal growth. [ABSTRACT FROM AUTHOR]

In this paper, dual underexpanded impinging jets are experimentally studied by measuring unsteady wall static pressure and temperature fields using high response semiconductor pressure sensors and infrared imaging camera(100 captures per sec) with dual converging sonic nozzles. The flow field is also visualized by means of high speed schlieren system (up to 70000 frame per second) to clarify the unsteady behavior of the jet structures such as barrel shock wave, and Mach disk. Experiments were performed with a blow down tunnel changing the parameters such as the nozzle to plate distance, the distance between the two nozzles, and wind tunnel pressure ratio. The nozzle to plate distance L and the distance between the two nozzles H are non-dimensionalized by the nozzle diameter D covering H/D=1.5, 2.0, and 3, L/D= 2, 3, and 4, and po/pb=1.0 − 5.0, where po and pb are stagnation pressure and back pressure respectively. Although the response of the infrared camera is quite different from that of the high speed camera, the unsteady correlation between the pressure and temperature fields is confirmed under some conditions. Also the high speed schlieren pictures and the wall static pressure fluctuations suggest that the generation of the Mach disk promote the unsteady behavior of the jets. After the confirmation of the correlation, a simple way to find the severe fluctuating region can be provided according to the two dimensional unsteady temperature images without a lot of unsteady pressure measurements. [ABSTRACT FROM AUTHOR]

In this paper, under-expanded impinging jets issued from converging circular and rectangular nozzles were investigated. The ratio of the distance between the nozzle exit and the plate L to the diameter D was set at 2, 3, 4 for the circular nozzle and 2, 3 for the rectangular nozzle. Two-dimensional temperature and static pressure distributions on the impinging plate were measured using an infrared camera and a semi-conductor pressure sensor and flow fields were visualized by means of schlieren method. Three-dimensional numerical calculations were also conducted by solving the three-dimensional compressible Euler equations and compared to the experimental results. As a result, it is found that the numerical calculations for the circular and the rectangular nozzles are in good agreement with the experiments. In the experiments, it is found that the stagnation temperature on the plate depends on the pressure in the settling chamber and the distance between the nozzle exit and the plate. The temperature and pressure distributions in the experiments illustrate that even in the case of the circular nozzle, the distributions on the impinging plate are non-axisymmetric, which is confirmed by the three dimensional calculations. The calculation for the rectangular nozzle indicates that two circulating regions occur immediately upstream of the plate. [ABSTRACT FROM AUTHOR]