Hydrothermal flame impingement experiments. Combustion chamber design and impingement temperature profiles

• Measurement of the impingement temperature profiles of hydrothermal flames injected as free-jets in a high pressure water bath.
• High pressure operation and experiments with flame powers up to 78 kW.
• Design of various nozzle configurations for the investigation of the entrainment behavior of water in the flame-jets.
• Investigation of the influence of trans-critical fluids properties in the impingement heat transfer of hydrothermal flames.
• Optimization results for the nozzle designs, in terms of minimum entrainment and maximum impingement temperature.

The current work presents the hydrothermal flame impingement experiments conducted for the design of a hydrothermal spallation drilling nozzle. The products of hydrothermal flames of mixtures of ethanol, water and oxygen were injected as free jets in a high pressure water bath. The nozzle design was based on ideas stemming from underwater welding and cutting of metal sheets. Water entrainment in the flame-jets and the heat transfer capabilities of flames injected from various nozzles have been analyzed by measuring their impingement temperature profiles on a flat stainless steel plate. It was found that the thermal-to-kinetic energy ratio of the jet has a direct influence on the entrainment of water in it. Furthermore, the cooling water of the combustion chamber was injected in various angles to the axis of the jet resulting to different entrainment rates. It was found that higher water injection angles reduced the rate of entrainment. Finally, it was indicated that at certain operational points of the jet, its trans-critical properties had an important influence on the impingement temperatures.

Figure optionsDownload as PowerPoint slide