Abstract With the growing demand for faster, higher, and more advanced aircraft, breakthroughs in aerospace propulsion technology remain an ongoing pursuit. In recent research and applications, pintle injectors have demonstrated outstanding performance due to their adjustable flow rate and stable combustion characteristics, making them the injector of choice for many new rocket engines. However, few studies have explored their feasibility in broader application scenarios. This study designed a sector combustion chamber equipped with three adjustable pintle injectors, using liquid oxygen/kerosene as propellants and an oxygen/kerosene torch igniter as the ignition device. A series of hot-fire tests were conducted. The experiments focused on the ignition process and combustion performance under idle-start conditions. Results showed that even at a low flow of 10% nominal rate, the sector combustion chamber maintained a combustion efficiency of 86.7%. The spray combustion characteristics of the pintle injectors governed the heat-release distribution, leading to high-temperature zones primarily located between two adjacent injectors. Consequently, thermal protection design must account for this circumferential variation in temperature distribution. This research verifies the feasibility of pintle injectors in sector combustion chambers, providing a basis for application in full-scale annular combustion chambers and offering a new explorable direction for the development of aerospace propulsion technology.
Abstract This study investigates the influence of five design parameters on the combustion characteristics of a three-strut combustion chamber through single-factor analysis, clarifying their relationship with combustion efficiency and resistance. A Halton sequence with mean squared error–based infill sampling was employed to generate a sample set, and an accurate surrogate model was developed using Gaussian process regression. The Nondominated Sorting Genetic Algorithm II (NSGA-II) was then applied to optimize the chamber geometry with the objectives of improving combustion efficiency and reducing resistance. Through clustering analysis, two distinct high-efficiency combustion modes were identified: a multizone violent combustion mode and a blended mild combustion mode. In the former, the rapid combustion of pilot fuel creates favorable conditions for subsequent fuel combustion, increasing the combustion efficiency from 73% to 93% compared with the baseline case; however, due to excessively abrupt flow field changes, the reduction in resistance is not significant. In the latter, the flame fronts merge and develop smoothly, and although it only improves combustion efficiency to 85% compared with the baseline case, it substantially reduces resistance from − 7,762 newtons (N) to − 8303 N . This work provides enhanced design flexibility for high-performance scramjet combustors.
Abstract Flow control technologies such as the Co-Flow Jet (CFJ) have demonstrated significant potential for improving aerodynamic performance. However, most existing studies treat CFJ parameters as fixed during aircraft conceptual design, limiting the ability to evaluate their system-level impact on aircraft performance. To address this limitation, this study proposes an efficient multidisciplinary design framework that integrates key CFJ design parameters into the conceptual design process of CFJ electric aircraft. The framework combines a quasi-three-dimensional aerodynamic analysis method with energy consumption and weight estimation models of the jet system, enabling rapid evaluation of aerodynamic performance, propulsion power consumption, and aircraft weight within a unified framework. Based on the proposed methodology, a multidisciplinary design optimization problem is formulated to improve aircraft cruise performance. The framework is applied to a representative aircraft configuration, and the predicted aerodynamic performance is validated against computational fluid dynamics simulations. The results demonstrate that the proposed framework can efficiently capture the coupled effects of CFJ aerodynamic benefits, jet system energy consumption, and additional structural weight. Parametric studies further reveal the sensitivity of optimal CFJ configuration to cruise velocity and fan efficiency, providing useful guidance for the preliminary design of CFJ electric aircraft.
Abstract Theoretical studies have shown that fuel type can significantly affect the performance of the green onboard inert gas generation system (GOBIGGS). In this study, a microchannel monolithic catalytic reactor was designed and fabricated, and a ground-based experimental platform for GOBIGGS was established. The operational reliability of the system was also verified. Combined with the compositional analysis of three aviation fuels using high-performance liquid chromatography (HPLC), the effects of fuel type on inerting rate, inerting effectiveness, product formation, and reactor temperature response were systematically investigated. The results show that the system can reduce the O 2 volume fraction in the tank vapor space to 12% within 45.5 min, reaching the commonly used inerting threshold for civil aircraft fuel tanks. Under the same experimental conditions, fuels with higher light-component contents exhibited faster system inerting rates. Because different fuel components have different hydrogen–carbon (H/C) ratios, fuel components with higher H/C ratios consume more O 2 to generate the same amount of CO 2 during the inerting reaction. In addition, the temperature of the monolithic catalytic reactor was closely related to the reaction rate. A higher inerting reaction rate led to a faster reactor temperature rise and a higher peak temperature. This study experimentally examined the apparent influence of fuel type on the inerting performance of a closed-loop GOBIGGS. The results provide engineering data under the tested conditions and may support future studies on fuel adaptability evaluation, reactor thermal management, and system operation optimization.
Abstract Existing literature focuses on closely spaced multijet and single-jet configurations, leaving a gap in understanding the interaction mechanisms arising from complex wave systems and wakes in a widely spaced multijet setup. This study presents an experimental investigation of the coupled interference mechanism in the flowfield of a body of revolution configuration with a Mach 6 crossflow and long-range tandem multijets. Schlieren imaging and electronic pressure-scanning techniques were employed to visualize the flowfield structure and measure the surface pressure distribution. The results indicate that the posterior jet exerts negligible influence on the surface pressure distribution and interference flowfield morphology both upstream of the anterior jet and in the immediately adjacent downstream region. The obstruction effect of the anterior jet on the crossflow enables the reverse flow of the posterior jet to propagate upstream within the wake of the anterior jet, thereby enlarging the separation zone and reducing the peak pressure. Furthermore, the reduction in the total pressure of the posterior jet attenuates the bow-shock and separation-shock intensities generated by the posterior jet, altering the wake separation characteristics downstream. These findings support an in-depth understanding of the flow phenomena associated with long-range tandem multijets.
