An indirect method implementing effect of the wind on moored ship experimental tests

Traditionally, moored ship tests with small-scale models only take into account the disturbance effect of waves. In this paper, the design and testing of a system also implementing the effect of wind in moored ships is analysed. The system is based on rotatory actuators acting on linear springs. This solution has a swift enough response to reproduce the fluctuating component of the wind. Three scenarios have been tested: waves, wind and combination of both. In order to assess the results, different sensors are connected to a computer for data acquisition, allowing the recording and subsequent analysis of the measured variables (forces in ropes, reactions in fenders and ship motions). The results obtained from the experiments show a great impact when wind effect is considered. A superposition effect is observed when waves and wind act together on the ship, emphasizing therefore the importance of taking the wind into account in berthed vessel tests, achieving safer and more realistic results

Cooling Strategies for Heated Cylinders Using Pulsating Airflow with Different Waveforms

Pulsate flow is an effective technique applied for cooling several engineering systems depending on their pulsate frequency. One very sound external flow pulsation application is heat transfer over heated bodies. In present work, an experimental design and numerical model of controlled pulsating flow according to generated pulsating frequency and wave shape around a heated cylinder were performed. The effects of pulsating frequency, amplitude, and mean velocity on the fluid flow and heat transfer characteristics over a heated cylinder were studied. The wave frequency varied from 2 to 12 Hz, and the amplitude varied from 0.2 to 0.8 m/s. Moreover, different waveforms were investigated to determine their effect on wall cooling. For constant wave frequency and amplitude, the most efficient wave in cooling was the sawtooth wave, with the average wall temperature after 30 s was 1.6 °C cooler than that of the forced convection case, followed by the triangular wave at 1.2 °C less. The heat transfer rate and the flow field were drastically influenced by the variations of these parameters. Optimization was conducted for each wave type to find the optimum wave frequency and amplitude. The optimizing showed that, the most efficient wave was the sawtooth with 12°C temperature reduction compared with that of the forced convection case, followed by the triangular. Furthermore, regression analysis was conducted to estimate the relationships between these variables and surface temperature. It was found that the wave amplitude had a greater role in cooling than that of the frequency