Experimental Study on the Deflagration Characteristics of the Liquid Propellant Spray Electrical Ignition and the Simplified Model Calculation
The liquid propellant atomization experimental apparatus, single pulse discharge device and the AC (alternating current) sequence discharge device have been designed to explore the electrical ignition method of HANbased liquid propellant. By using of high speed camera system, the electrical ignition experiment study of the HAN-based liquid propellant LP1846 under different injection pressure has been conducted. The results indicate that: the spray can be ignited instantly by single pulse discharge method as the Sauter mean diameter of the LP1846 droplets is in the region of 10~20 μm, but there is deflagration ability; stable ignition can be got by alternating current pulse discharge method as SMD of LP1846 droplets is in the region of 40~50 μm . Based on the experiment, the simplified model of LP1846 atomization pulse discharge ignition delay time has been proposed. The numerical results coincide well with the experimental results.
Combustion Characteristics of Energetic HAN/Methanol-Based Monopropellants
The pressure dependence of burning rate for two HAN/Methanol-based liquid monopropellants is studied between 0.74 and 7.3 MPa. The less energetic formulation, HAN269MEO15, is found to exhibit different combustion characteristics above 1.21 MPa and below 1.14 MPa. Changed characteristics include a sharp increase in the burning rate, and a drastic change in the combustion behavior. HAN284MEO17 also exhibits two distinct combustion behaviors, however the transition occurs around 2.9 MPa. The appearance of a flame, a pronounced increase in the burning rate slope, and a characteristic change of the temperature-time trace of the reaction zone all indicate a change in the burning mechanism at this pressure. Surprisingly, the burning rate of the more energetic formula is lower than the less energetic one. Temperature measurements of the reaction zones of both propellants indicate that the boiling points of water and methanol play an important role in the combustion processes. Since the measured reaction zone temperatures are significantly less than calculated adiabatic flame temperatures, it is likely that the propellants are not reacting to their full potential in the near field.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.