Design Of Emergency Breakaway Device For Helicopter Hovering Refueling System

China is a big shipping country and the shipping industry has made tremendous contributions to China’s economic development.When the vessel is in distress at sea,the marine rescue system consisting of rescue boat-rescue aircraft will conduct timely search and rescue.In the event of bad sea conditions,the rescue helicopter could not be parked on the rescue boat,and it was necessary to hover and refuel to replenish the fuel to ensure the timeliness of the rescue.In the helicopter hover refueling system,the emergency disengagement device is an important structure for controlling the automatic disconnection of the oil pipeline in an emergency.This project designed an emergency breakaway device with a breaking force of 1700 N-2000 N.The main research contents are as follows:1.Two kinds of emergency disengagement devices are designed:the crow type emergency disengagement device and the plug type emergency disengagement device,respectively,the force analysis of the two emergency disengagement structures is carried out,and the calculation formula that affects the breaking force of the disengagement process is obtained and passed.Orthogonal tests and simulations obtained structural parameters consistent with the design pull-off force.2.The prototype of the emergency breakaway structure was processed,and the tensile test was carried out on the emergency breakaway structure.Through experiments,various parameters suitable for different breaking forces are obtained.The crow type emergency breakaway structure meets the requirements.The better parameters of the breaking force are the crow contact angle of 15°,the spring stiffness of 77 N·mm/°,the pre-tightening angle of 8°,the crow contact angle of 25°,the spring stiffness of 119 N·mm/°,and the pre-tightening angle of 8°.,the crow contact angle is 35°,the spring stiffness is 153 N·mm/°,and the pre-tightening angle is 8°;the preferred parameters of the plug emergency disengagement structure are compression springs with a stiffness k of 45 N/mm and an initial length of 12 mm.A plug with a height h of 10 mm and a plug compression cover with a contact angle β of 55°.3.The water-passing experiment was carried out to test the flow capacity,sealing capacity,pressure loss and the breaking force and leakage degree of the two emergency detaching devices.The experimental results show that the two emergency detaching devices are at the rated work.The flow capacity and sealing capacity under the condition have the ability to automatically close the pipelines at both ends after disconnection;the pressure loss of the emergency breakaway device under the helicopter refueling working state is obtained to compensate the fuel pressure;the experimental results show that In the water tensile test,the breaking force of the emergency detaching device is within the design requirements.The leakage flow rate after the completion of the breakaway is 0,and the cumulative liquid leakage during the breakaway process is less than 200 mL.It is considered that the leakage amount should be less in practical applications.