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"Gas generators"
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Experimental study on heat transfer efficiency of pyrotechnics enhanced by gas generator
This paper investigates the impact of the gas generator on the heat transfer of pyrotechnics. The enhancement effect is examined using a combination of experimental and engineering methods. The results demonstrate that the pyrotechnics exhibit favorable thermal performance based on performance testing. The heat transfer efficiency of the pyrotechnics can be enhanced by adjusting the structure of the gas generator, including the filter and gas outlet, as well as the shape of the pyrotechnics. However, regardless of the structure, there is a maximum peak where the gas generator achieves the highest rate of heat transfer enhancement for the pyrotechnics. Through analysis of the heat transfer experiment process, it can be concluded that the gas generator effectively reduces the heat transfer time of the pyrotechnics and minimizes heat loss during the process. Even when using coolant, the heat transfer efficiency of the pyrotechnics remains high at 69.31% after the gas generator enhancement.
Journal Article
Improvement of Gas Generator Technology for Energy Processing of Agricultural Waste
The article discusses the issues of increasing the energy efficiency of processing agricultural waste in a gas generator. The main goal of this technological process is the production of gas fuel from agricultural waste. This fuel is generator gas. The energy value or calorific value of the generator gas depends on the elementary composition of the solid fuel being processed (straw, animal droppings, peat, wood, carbon-containing industrial waste, etc.) and also on the conditions under which chemical reactions take place in the gas generator. In order to improve the gas generator technology, some innovative technical solutions have been proposed. The solutions are related to controlling the supply of the oxidizer (atmospheric air) to the reaction zone of the gas generator, to recuperate the thermal energy of the gas generator and the combined combustion engine of the power plant for the needs of the gasification process. The solutions are also related to the use of compensation and accumulation systems for supplying the consumer with generator gas and to the spatial positioning of the gas generator housing. The control mode of the oxidizer supply to the reaction zone of the gas generator was also investigated. The analysis of the experimental material allows us to draw a conclusion about the positive effect of control modes on the energy value of the generator gas at non-nominal consumption of generator gas by the consumer. This is a consequence of the optimization of the flow speed of the oxidant from the blowing nozzles of the gas generator. According to the tests of the chemical composition of generator gas in gas generator, depending on the number of electromagnetic valves operating, the largest CO content (approx. 17%) was with five valves, CO2 (approx. 5%) with the lower number of valves, and the O2 was with the highest number of valves. The pressure gauge (discharge in gas generator) was the biggest, according to the lower number of valves. The biggest gas consumption was approx. 6 m3/h.
Journal Article
Effect of Metal Oxides on the Pyrolytic Behavior and Combustion Performance of 5-Aminotetrazole/Sodium Periodate Gas Generators in Atmospheric Environment
5-aminotetrazole (5AT)-based gas generators, particularly the 5AT/NaIO4 system, have garnered interest for their high gas production and energy potential. This study investigates the impact of various metal oxides (MnO2, Al2O3, TiO2, CuO, Fe2O3, MgO, ZnO, and MoO3) on the thermal decomposition and combustion performance of 5AT/NaIO4. The REAL calculation program was used to infer reaction products, which indicated that the gas products are almost all harmless, with negligibly low percentages of NO and CO. Thermogravimetric analysis revealed that metal oxides, especially MoO3, significantly advance the decomposition process above 400 °C, reducing the activation energy by 130 kJ/mol and lowering critical ignition and thermal explosion temperatures. Combustion performance tests and closed bomb tests confirmed MoO3’s positive effect, accelerating reaction rates and enhancing decomposition efficiency. The system’s high Gibbs free energy indicates non-spontaneous reactions. These findings provide valuable insights for designing environmentally friendly gas generators, highlighting MoO3’s potential as an effective catalyst.
Journal Article
Thrust Control Method and Technology of Variable-Thrust Liquid Engine for Reusable Launch Rocket
A high-precision variable-thrust control method based on real-time measurement of pintle displacement and closed-loop feedback control is proposed to solve the technical problems of deep throttling variable-thrust regulation and control of pintle liquid rocket engines (LRE). By optimizing the system structure and control parameters, the closed-loop control of displacement with high precision and a fast response under a wide range of variable thrust can be realized, and thus the large-range, fast-response, and high-precision control of the chamber pressure, equivalent to thrust, can be indirectly realized. The chamber pressure response time is not more than 0.3 s, the overshoot is not more than ±3%, and the pulsation amplitude is not more than ±5%, which can meet the technical requirements of the large-range thrust adjustment and control of variable-thrust LRE of reusable launch rockets. The proposed variable-thrust LRE thrust control system is simple, reliable, and easy to use and maintain, which solves the problem of the large range, high precision, and fast response of thrust adjustment and control. The proposed system can provide important technical support for carrier rocket recycling and launch cost reduction. This is the first time a closed-loop control method of displacement of an integrated gas generator/flow regulator to achieve a 5:1 large-range continuous-variable-thrust control for the LRE of a reusable launch rocket has been proposed.
Journal Article
Analysis and design of the gas generator multifunctional bulkhead considering the thermal and structural loads
The operation of gas generators brings relatively high thermo-mechanical loads on the gas generator structure. The objective of this article is to determine the operating conditions, in terms of mechanical loads at extremely high temperatures in very limited and narrow space, of a multifunctional bulkhead for application on specific kinds of gas generators with back-to-back rotor concept. The paper contains numerical analysis and experimental investigation for determining the loads and behavior of the structure. Numerical analysis indicates that there is significant influence of the Tesla turbine effect on flow parameters. Also, uneven pressure distribution and significant thermal loads are identified. With experimental investigation and subsequent exploitation tests, it was concluded that the presented methodology identifies the operating conditions, truthfully simulates the bulkhead stress state and deformations and that the presented design solution satisfied all demands. Regarding results obtained by these numerical simulations, the innovative design solution for the multifunctional bulkhead was proposed.
Journal Article
Porous Structure Formation of Aerated Concrete with Variational Properties
The main drawbacks of aerated concrete preparation traditional technology are considered. The method essence for the porous structure formation of aerated concrete products with variational properties is formulated. The main factors affecting aerated concrete products properties of varying density and strength along the cross-section are indicated. The mold cover closed surface with a circular opening area effect on aerated concrete products main properties is shown and its optimum value is revealed. The traditional and modern types gas generators influence on gas evolution kinetics, mixture swelling height, gas generators stability in time and variable density and strength on the cross-section aerated concrete products main properties are considered.
Journal Article
Effects of Local Mixing Ratios and Mass Flow Rates on Combustion Performance of the Fuel-Rich LOX (Liquid Oxygen)/kerosene Gas Generator in the ATR (Air Turbo Rocket) Engine
This paper presents a numerical simulation analysis of the flow and combustion characteristics of a fuel-rich LOX (liquid oxygen)/kerosene gas generator in an ATR (air turbo rocket) engine, examining the effects of local parameters on the combustion flow field and performance. The analysis considers variations in unit injector mixing ratios and unit mass flow rates. The results indicate that as the mixing ratio in the inner-ring injectors increases (while the mixing ratio in the middle-ring injectors decreases), the oxygen concentration area near the axis zone and the 50% radius zone of the gas generator expands. Conversely, the kerosene concentration area near the axis zone decreases while gradually increasing near the 50% radius zone. In the flow direction section, there is an inverse relationship between the variation trend of local temperature and the oxygen concentration in the local area. As the oxygen concentration increases, the temperature decreases. The temperature distribution across the cross-section of the gas generator exhibits a circular pattern. When the mixing ratio (or mass flow rates) of the unit injector are perfectly balanced, the temperature distribution becomes highly uniform. A larger disparity in flow rate between the inner ring injector and the middle ring injector leads to a lower combustion efficiency. This effect differs from the effect of the mixing ratio difference between the two injector rings. Increasing the mixing ratio in the inner-ring injectors (or decreasing the mixing ratio in the middle-ring injectors) initially leads to a rise in combustion efficiency, followed by a subsequent decline. The maximum combustion efficiency of 89.10% is achieved when the mixing ratio is set to Km-1 = 0.7 and Km-2 = 2.79, respectively. Increasing the flow rate in the inner-ring injectors (or decreasing the flow rate in the middle-ring injectors) initially leads to an improvement in combustion efficiency, followed by a subsequent reduction. The maximum combustion efficiency of 86.13% is achieved when the mass flow rate is set to m-1 = m-2 = 0.1 kg/s.
Journal Article
Enhancing Fault Detection and Isolation in All-Electric Auxiliary Power Unit (APU) Gas Generator by Utilizing Starter/Generator Signal
This study proposes a novel paradigm for enhancing the fault detection and isolation (FDI) of gas generators in all-electric auxiliary power unit (APU) by utilizing shaft power information from the starter/generator. First, we conduct an investigation into the challenges and opportunities for FDI that are brought about by APU electrification. Our analysis reveals that the electrification of APUs opens new possibilities for utilizing shaft power estimates from starters/generators to improve gas generator FDI. We then provide comprehensive theoretical and analytical evidence demonstrating why, how, and to what extent the shaft power information from the starter/generator can fundamentally enhance the estimation accuracy of system states and health parameters of the gas generator, while also identifying key factors influencing these improvements in FDI performance. The effectiveness of the proposed paradigm and its theoretical foundations are validated through extensive Monte Carlo simulation runs. The research findings provide a unique perspective in addressing three fundamental questions—why joint fault diagnosis of the starter/generator and gas generator in all-electric APUs is essential, how it can be implemented, and what factors determine its effectiveness—thereby opening up promising new avenues for FDI technologies in all-electric APU systems.
Journal Article
Dynamics of Pressure in a Well During Treatment of its Face Zone by a Thermal Gas Generator
An analysis of the pressure wave field that appears in a well as a result of combustion of a powder charge of a thermal gas generator is presented. Based on the solution of the problem obtained by the spectral method, it is shown that in the case under consideration the well represents a resonator that implements wave perturbations of discrete spectrum. Four types of possible pressure fluctuations in the well are determined, which correspond to the implementation of various combinations of periodic, aperiodic, and resonant modes. For the case of realizing only periodic modes, a comparison with experiment was made, which indicates the predominant contribution of the zero mode. From this it also follows that approximation of oscillations only by the zero mode is possible at both small and large amplitudes. The value of the apparent damping coefficient is approximately twice higher for high-amplitude processes, while the circular frequency remains unchanged. It has been established that the attenuation of pressure waves occurs mainly due to elastic losses into the medium surrounding the well. The contribution of dissipative processes caused by the viscous friction of the fluid in the well is relatively small.
Journal Article