Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

Further studies of the extrapolation of near field overpressure data

Abstract: Technique of extrapolating measured near-field overpressure data to larger altitude applied to wind tunnel overpressure data

Experimental study of spontaneous ignition and non-premixed turbulent combustion behavior following pressurized hydrogen release through a tube with local enlargement

Abstract: Pressure records, flame detection and high-speed photography are used to study the spontaneous ignition and non-premixed turbulent combustion behavior following high-pressure hydrogen release through a cylindrical tube with local enlargement into the semi-enclosed space. The study shows that the leading shock wave is partly reflected when it impacts on the vertical walls in the local enlargement section. The pressure behind the reflected shock wave has a significant increase compared with that behind the leading shock. Moreover, the leading shock wave speed decreases firstly and then increases as it passes through the enlargement. It is found that the presence of the local enlargement structure can significantly facilitate the occurrence of spontaneous ignition. The minimum storage pressure of spontaneous ignition is only 1.98 MPa in the tube with local enlargement, which is lower than that in a constant cross-section tube. The possible positions of initial ignition inside the tube and the delay times of ignition for different burst pressures are obtained. After the hydrogen flame comes out from the tube, a ball of flame is formed around the tube outlet and propagates outward. Then, the noticeable non-premixed turbulent combustion of hydrogen occurs in the semi-enclosed space, which leads to the increase of the pressure in the chamber. Twice peaks of overpressure are observed successively and the second pressure peak has a lower intensity compared with the first peak value. Moreover, the maximum overpressure of non-premixed turbulent combustion increases with the release pressure.

Influence of vacuum degree on the effect of gas explosion suppression by vacuum chamber

Abstract: In order to study the influence of vacuum degree on gas explosion suppression by vacuum chamber, this study used the 0.2 mm thick polytetrafluoroethylene film as the diaphragm of vacuum chamber to carry out a series of experiments of gas explosion suppression by vacuum chamber with the vacuum degree from −0.01 MPa to −0.08 MPa. The experimental results show that: under the condition of any vacuum degree, vacuum chamber can effectively suppress the explosion flame and overpressure; as vacuum degree changes, the effect of gas explosion suppression using vacuum chamber is slightly different. Vacuum chamber has obvious influence on propagation characteristics of the explosion flame. After explosion flame passes by vacuum chamber, the flame signal weakens, the flame thickness becomes thicker, and the flame speed slows down. With the increase of the vacuum degree of vacuum chamber, the flame speed can be prevented from rising early by vacuum chamber. The higher the vacuum degree is, the more obviously the vacuum chamber attenuates the explosion overpressure, the smaller the average overpressure is, and the better effect of the gas explosion suppression is. Vacuum chamber can effectively weaken the explosion impulse under each vacuum degree. From the beginning of −0.01 MPa, the vacuum chamber can gradually weaken explosion impulse as the vacuum degree increases, and the effect of gas explosion suppression gradually becomes better. When the vacuum degree is greater than −0.04 MPa, the increase of vacuum degree can make the explosion overpressure decrease but have little influence on the explosion impulse. Therefore, the vacuum chamber has the preferable suppression effect with equal to or greater than −0.04 MPa vacuum degree.