Газодинамічні закономірності процесів раптової розгерметизації відсіків літального апарата.

Abstract

The Thesis presents the results of numerical and experimental researches of gas-dynamic regularities for processes during aircraft compartment sudden depressurization. The hypothesis about definition of functional dependency between parameters of polytrophic process with constant polytrophic exponent ratio to define the gas-dynamic processes and gas pulsation in the compartment, for gas flow without flow ratio and for fulfilment of quasi-stationary condition were suggested in the present work. The hypothesis were proven and justified by the results of numerical and experimental researches conducted at the test rigs, on-ground and in-flight conditions on the models and actual full-scale compartments. For the first time were summarized and developed the research major stages for gas-dynamic and aeroacoustic processes in the compartments. For the first time the test rigs were developed to research: the gas-dynamic and aeroacoustic processes of gas outflow from the compartment, the gas flow in the gap and gas flow load impacted on the shield. Basing on the results of the theoretical, computation-and-experimental and test rig researches performed on the models and aircraft full-scale compartments the following has been backgrounded and proposed: the method of aircraft cabin air parameters definition during compartment depressurization, the conceptual principles of functional dependency definition for gas-dynamic process parameters at compartment sudden depressurization, the method of functional dependency definition for gas-dynamic process parameters in the compartment with taking into account the model by an a priori information, engineering procedure of compartments gas-dynamic calculations at aircraft compartment sudden depressurization. For the first time were defined the regularities of gas-dynamic and aero-acoustic processes inside the compartment during its sudden depressurisation into the mating compartment and into unlimited volume, during gas outflow via various holes like “round hole”, “lacerated hole”, “slot” and hole based on “plug” effect. For the first time were defined the functional dependencies for parameters of polytrophic process with constant polytrophic exponent ratio for stagnated flow parameters in the compartment during gas outflow with taking into account the gas pulsation. The equations and partial solutions were obtained for gas flow load impacted on the shield with alternating force and for gas outflow via the variable area hole. The researches were conducted and compartment parameters dependencies were defined for gas outflow from “big” compartment with taking into account an elastic properties of compartment, basing on variable mass body, with gas (energy) input (output), for multiple volume cabin, for definition of gas flow and gas pulsation spreading velocity, for gas constant pressure support criteria and constant temperature support criteria, gas damaging impact during pneumatic tyre burst in the aircraft wheel bay. To define a leakage from pressurized cabin the numerical method based on the experimental data obtained during the tests of aircraft actual compartment was developed for the first time. Basing on aircraft in-flight check of cabin hermeticity the functional dependencies were defined for parameters of gas-dynamic processes in the compartment at air parameters polytrophic variation in the cabin with constant polytrophic exponent ratio. For the first time the statistics analysis were made for actual pressurized cabins leakages, and also their equitations were obtained depending on cabin volume, cabin layout and aircraft operation conditions. Basing on the test rig and flight test research results the effective procedures and means to reduce the gas pulsation in the heat exchanger cooling line of bleed air system at the aircraft engine pylon and in the input to outflow valve of aircraft cabin pressure control system were developed. Basing on the obtained scientific and practical results, for the first time the airplanes were certified upon requirements for compartment sudden depressurization and pneumatic tyre burst in the wheel bay in accordance with АП-25, FAR-25 and CS-25 aviation regulations.