{'fraction_non_alphanumeric': 0.014053579270970576, 'fraction_numerical': 0.001756697408871322, 'mean_word_length': 4.994736842105263, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Experimental research into aerodynamic characteristics of a nacelle with the enabled system of engine thrust neutralization

We have conducted an experimental study into aerodynamic characteristics of the structural scheme “wing ‒ two­circuit engine nacelle”. The data were acquired in the course of work of a promising system for the neutralization of a two­circuit engine’s thrust of a large by­pass ratio at aircraft landing. The relevance of the conducted study relates to the improvement of operational performance of a passenger aircraft. Based on the analysis of functions and principal schemes of reversible devices at cargo and passenger airplanes, we have proposed a promising method to neutralize the thrust of a two­circuit engine with a high by­pass ratio. Physical essence of the method for neutralization of the engine’s thrust is to substantially restrict an airflow into the engine by a technique to rotate working blades of the fan at the time of landing. We have devised a specialized procedure for conducting a weighting and drainage experiment with a model of the nacelle of a turbojet two­circuit engine in a wind tunnel. The obtained experimental data make it possible to evaluate the limits of the investigated method for neutralizing the thrust in order to shorten the length of aircraft run. By conducting a drainage experiment and applying a tuft flow visualization technique, we identified the detachment of a flow at the outer surface of the nacelle’s model with a completely closed entrance. The presence of the flow detachment predetermined an increase in the frontal drag of the nacelle model by approximately 2.5 times, revealed by the weight experiment. In the course of the weight experiment it was established that the existence of a screening surface (while the engine’s nacelle approaches a runway) increases frontal drag of the nacelle model by approximately 14 %. The drainage experiment found that such an increase in the frontal drag was due to a significant redistribution of pressure at the surface of the nacelle model. The study has shown that the idea of closing the entrance to the engine that has a large by­pass ratio at the time of aircraft landing is one of the promising methods for shortening the run length of the aircraft