| The detonation initiation is the key technology of Pulse Detonation Engine (PDE). In order to initiate in a short distance and low resistance, the present research was concerned with the method of combining numerical simulation with experiment. Three new technologies of detonation initiation were investigated in the single tube and multi-tube PDE systems. The results attained from the research including:1. The research of combined initiation device(1) The working principle and flow characteristics of three different types of detonation device were studied. V-blending in the three devices played a good role in fuel-air mixing, and the injection of hollow tube can increase air flow turbulence intensity and enhance the ignition. The velocity contrast in the outlet of the device also increased the turbulence intensity of export flow.(2) Lots of tests were conducted with three different types of detonation device, filling liquid gasoline and air. The used pulse detonation tube has a size of about 1130 mm in length and 114 mm in diameter. The PDE could be operated at 40 Hz stability. The characteristics of detonation wave in pulse detonation engine mainly included flame propagation speed in the PDE chamber, the distance of deflagration to detonation transition and the characteristics of detonation wave.2. The technology of branch pipe initiation(1) Through numerical methods, three different branch modes were investigated in the way of direct initiation. The numerical methods included detailed Chemkin chemical reaction model. The results showed that three branch pipes could effectively achieve detonation ignition. The structure of the total pressure pipe could generate high pressure area in the wall near the entrance of branch pipe.This would help the high temperature gas generated in the first tube enter into the branch pipe and promote the formation of detonation wave.(2) Two same detonation tubes, 62mm in diameter and 1259mm in length, were connected end to end with branch pipe, 32mm in diameter and 1000mm in length. The PDE could initiate successfully and work coordinately in the 20~33 Hz. Through the data recorded by ion probe, the flame propagation speeds were calculated in different frequencies. When the engine working between 20~30 Hz, the flame propagation speeds in two detonation tubes would increase with the increasing frequency. At the same frequency, the flame propagation speed in the detonation tube 2 was faster than the one in the detonation tube 1. 3. The technology of detonation initiation with toroidal shock wave focusing near the wall(1) Through numerical methods, flat closed end and semi-circular closed end were investigated in the way of direct initiation. The numerical methods included detailed Chemkin chemical reaction model. The results showed that the position of shock wave focusing in the detonation chamber with semi-circular was ahead of the position in the detonation chamber with flat closed. It proved that the semi-circular closed end could better promote the focusing of shock wave.(2) The research was about the technology that used the toroidal shock wave focusing to direct initiate the combustible mixture of the main detonation chamber in the small space near the wall channel. Lots of tests were conducted, filling with the mixture of hydrogen and air. The used annular space has a size of about 400 mm in length, 89 mm in inner diameter and 114mm in outer diameter. The factors of toroidal shock wave focusing initiating the combustible mixture of the main detonation chamber in the small space near the wall channel were studied. The technology of indirect detonation initiation, different surfaces of closed end and different head distance were studied.(3) The engine was researched by the multi-cycle experimental method, filling with the mixture of gasoline and air. In the experiment, the space between spoilers and the number were adjusted. Although the engine could work continuously in 20~25 Hz, there were not detonation waves. |
PDF Full Text Request