The algorithm for estimating reserves of the working process stability in combustion chambers and gas generators of liquid rocket engines

The experimental evaluation of the working process stability with respect to acoustic oscillations in combustion chambers and gas generators of liquid rocket engines is one of the main methods used in rocket engine construction. External and internal disturbing devices using explosive hexogen often lead to the damage to the fire walls and struc- tural elements of the aggregates The disadvantages of traditional external impulse devices also include a considerable wide range of the pressure pulses values generated by them in the combustion chamber with the same value of the sam- ple of the explosive and with the constant parameters of the atmosphere in the combustion chamber, which is due to the scatter of the explosives characteristics. An alternative approach is proposed for creating a pulse effect on the working process in the combustion chamber by exploding an electrical conductor. The disturbing device is made with an explo- sive chamber connected by a channel with the reaction volume of the combustion chamber. In the electro-impulse dis- turbing device a thin wire fastened to isolated electrodes is used instead of the charge of the explosive. As a substance used to create a pressure pulse, this generator uses gas filling the blasting chamber, the mass of which depends on the pressure in the combustion chamber and in the chamber of the electro-impulse perturbative device. If one immediately heats this gas to a temperature of several thousand degrees, one can get a gas that is close in parameters to the com- bustion products of explosives in traditional external impulse devices. Such heating can be carried out by discharging through a wire of an electric capacitor charged to several thousand volts. First, instantaneous (for several microsec- onds) evaporation of the wire, and then through the plasma channel formed at the site of the wire, the final discharge of the capacitor takes place, with virtually all of the energy stored in the capacitor discharged. The plasma temperature in this case, according to different sources, can reach from several tens of thousands to one million degrees. The gas is also heated by adiabatic compression with a shock wave. The metal particles formed after the evaporation of the wire and the condensation of the vapor have a value of several nanometers and, therefore, do not damage the inner layer of the combustion chamber. The methodological bases are considered and the algorithm for estimating the stocks of stability to acoustic vibrations from the reaction of the combustion process to such pulsed artificial disturbances is developed. There have been developed electro-impulse disturbing devices that reduce the risk of damage to the compo- nents of liquid rocket engine assemblies in full-scale and model test, and have an obvious prospect for widespread use.