Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering

Journal Information
ISSN / EISSN : 0954-4100 / 2041-3025
Published by: SAGE Publications (10.1177)
Current Coverage
SCOPUS
LOCKSS
EI COMPENDEX
INSPEC
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Latest articles in this journal

Thillaikumar Thangaraj, , Thanigaiarasu S
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221097537

Abstract:
The mixing enhancement and core length reduction of a jet without significant loss of thrust are essential for reducing infrared radiation, mitigating aeroacoustic noise, improving combustion characteristics, and thrust vectoring. The jet mixing can be improved by manipulating the flow behavior. In subsonic and sonic jets, the flow manipulation may be achieved by utilizing nozzles with non-circular geometries that shed vortices of varying size due to their non-uniform azimuth curvatures. Non-uniform vortices generate differential spreading along the nozzle’s perimeter, causing axis switching and improving entrainment characteristics. Therefore, the present study examines the effects of two non-circular nozzle exit shapes (elliptic and square) on the mixing augmenting efficacy at subsonic and sonic flow conditions. The circular nozzle is tested for comparison. Both quantitative and qualitative analyses evaluate the efficacy of nozzles with non-circular exit geometries. Among the configurations investigated, the elliptic nozzle is superior in shortening the potential core length and enhancing the jet spread. A maximum reduction of 18.75% in core length with rapid jet decay was accomplished with the elliptic nozzle. The measurement of pressure profiles at different streamwise locations reveals that the spread rate is greater for elliptic and square jets than their circular counterpart. The elliptic jet exhibits the highest spread along the minor-axis direction compared to the major-axis direction. The differential jet spread rate in the elliptical jet causes an early axis-switching––direct evidence of mixing augmentation. Shadowgraph images show the asymmetric pattern of shock cell structures and differential spreading in elliptic and square jets.
Xiang Liu, Lianglinag Lv,
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221081518

Abstract:
Membrane solar array has attracted a lot of attentions in recent years because of the advantage of light-weight, low-cost, and high-folding-ratio. Meanwhile, the membrane solar array structure also pose challenging large-amplitude vibration issue which will impact the performance of the spacecraft significantly. In this paper, active nonlinear vibration control of a membrane solar array structure is studied. Based on the nonlinear finite element method, a nonlinear dynamic model of the structure is established. The optimal positions of piezoelectric actuators are determined by optimizing a controllability optimization criterion with Particle Swarm Optimizer algorithm. An active controller is designed to suppress the undesired nonlinear vibration based on the linearized dynamic model by using the LQR control method. Simulation results show that the designed active controller can suppress the nonlinear vibration of the membrane solar array structure effectively, and the optimally placed actuators can produce better control effect with smaller control inputs.
, Jin Yan, Ali Elham
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221095370

Abstract:
The Ultra-High Aspect Ratio Wing (UHARW) concept can improve the aircraft’s aerodynamic efficiency and reduce fuel consumption. The Twin-Fuselage (TF) configuration is one of the promising concepts for the UHARW design to reduce the wing bending moments and shear forces. This paper presents the development of a semi-empirical method for the weight estimation of TF aircraft in the initial sizing stage. A physics-based wing weight estimation method is improved for higher fidelity aerodynamic analysis and modified for composite material structures of TF aircraft. This method is used in the design of experiments and the results are applied for regression analysis to establish a semi-empirical method. Eventually, the established semi-empirical weight estimation method is integrated into a TF aircraft conceptual design and performance analysis framework. A mid-range TF aircraft and a long-range TF aircraft are designed and sized to illustrate its application and efficiency in rapidly estimating the TF aircraft weight breakdown.
Gobiha D, Rohith G
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221081820

Abstract:
Nonlinear controllers have been extensively abstracted in recent times. Nevertheless, real time implementation for underactuated MIMO physical systems is rarely attempted. This work proposes a nonlinear framework based on dynamical analysis and the sliding mode based control technique to control a highly coupled and nonlinear MIMO underactuated control moment gyroscope. First, an analytical formulation based on dynamic characterization is proposed to understand both the unactuated dynamics and the performance constraints of the gyroscope. This characterization helps in designing a feasible nonlinear sliding mode controller which helps in a simple and straightforward control of the system through the entire operating regime. The effectiveness of the proposed nonlinear control and analytical framework is established by successful implementation on the experimental gyroscope setup.
Wenfeng Xu, Peng Sun, , Shaobing Han, Guogang Yang
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221083346

Abstract:
The leakage flow generated by rotor clearance seriously affects efficiency and stability of a compressor. In order to reduce the effect of leakage flow, the tip winglet has been applied at the tip of a transonic compressor cascade. Numerical simulation has been used to investigate the influence of tip winglets with different fusion heights on the flow field structure. Furthermore, the effect of winglets was analyzed under different clearance heights and incidence angles. Results reveal that the winglet can weaken the kinetic energy of the leakage flow. The development of the leakage vortex along the pitchwise is suppressed, and the total pressure loss is decreased near the tip. The increase in the tip separation vortex scale leads to a remarkable decrease in the leakage flow rate. With the increase in fusion height, the scale of tip separation vortex decreases gradually, and the suppression effect on the leakage flow rate is weakened. The optimal scheme can reduce the loss by 3.3% and leakage flow rate by 13.4%. The suppression effect of the winglet on flow loss increases gradually with the increase in incidence angle. Moreover, the suppression effect of the winglet on leakage flow and flow loss increases first and then decreases with the increase in tip clearance.
Yunes Sh. Alqudsi, Ayman H Kassem, Gamal El-Bayoumi
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221090690

Abstract:
This paper presents a general real-time, numerically stable optimization framework for time polynomial-based trajectory generation of autonomous aerial robots. The proposed general optimization framework (GOF) allows various optimization criteria for trajectory generation cost-function, such as minimizing the trajectory total length, time, and position derivatives. Minimizing position derivatives includes velocity, acceleration, jerk, and snap, or any combination of them. This study considers the quadrotor as the test platform. By exploiting tools from the calculus of variations, differential flatness property, and polynomial-based trajectories, the developed algorithm finds feasible trajectories without extensive computational sampling and iterative searching in the high-dimensional state space of quadrotor dynamics. The GOF includes a segment-wise gradient descent-like algorithm to iteratively decrease the allowed time of each segment individually so as to avoid getting stuck at a local minimum. The comparison analysis with existing methods validated the numerical stability and computational speed advantages of the proposed approach. It also shows that the algorithm is suitable for the real-time generation of high-performance long-range trajectories consisting of a large number of waypoints and high-order piecewise polynomials. An animated simulation of this work is available at https://youtu.be/E1AC1vyPqOE
, Changsheng Gao, Wuxing Jing
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221088361

Abstract:
In this paper, a ballistic missile terminal penetration scenario is studied, which contains three participants: target, missile, and defender. The ballistic missile attempts to hit the target while evading the defender. A maneuvering penetration guidance strategy that balances both the guidance accuracy and penetration capability is proposed through deep reinforcement learning. Reward shaping and random initialization are applied to improve training speed and generalization, respectively. The proposed strategy is developed based on the twin delayed deep deterministic policy gradient algorithm. It directly maps observations to actions and is an end-to-end guidance scheme that does not require an accurate model. The simulation results show that the proposed strategy has higher penetration probabilities than conventional strategies for different initial heading errors and even for defenders with different guidance laws, which indicates its good robustness and generalization. For different initial heading errors, it has learned different maneuvering modes and has certain intelligence. In addition, it is computationally small, does not consume much memory, and can be easily applied on modern flight computers.
Kübra Solak, Cihat Arslantürk
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100221088362

Abstract:
Space radiators are used to reject waste heat from power units, electronic devices, and various equipment in space vehicles. It is important that radiators can achieve the heat desired to be dissipated into space with the least mass. With a view to ensuring this aim, the heat transfer calculations that must be performed must be highly accurate. Therefore, the variation of conductivity with temperature should also be taken into account in the mathematical model. This paper presents heat transfer performance and optimization of a fin array consisting of straight fins put axially on a tube and radiating heat into deep space. The mathematical model yields the governing equation as a highly nonlinear integro-differential equation which is solved by the variation of parameters method (VPM). By applying an appropriate optimization procedure, the conduction–radiation parameter, Nc, providing maximum heat transfer is obtained for a given fixed fin profile emissivity, ε, opening angle among the fins, γ, and thermal conductivity parameter describing the variation of thermal conductivity, β. For the range of suitable problem parameters, optimum values of the dimensionless conduction–radiation parameter Nc, which is a combination of thermal and geometric quantities, are expressed in ε and γ for a given β. The correlation equations are expected to provide remarkable benefits to the designer.
Xiaolong Huang, Ning Li, , Yang Kang
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering; https://doi.org/10.1177/09544100211072920

Abstract:
In order to research the operation synchronous of dual-tube pulse detonation engine, the operation performance and acoustic behavior of dual-tube pulse detonation engine under different fill fractions are studied experimentally. The results show that the instability of deflagration to detonation transition is the main reason for the non-synchronous work of the two tubes. With the increase of fill fraction, the detonation sound pressure increases gradually. In the region near the tube exit, the pressure and velocity of the shock wave attenuate rapidly, and the attenuation speed gradually slows down while the propagation distance increases. The time interval of detonation waves arriving at the tube exit of the two tubes can significantly affect the peak sound pressure and the duration of the sound wave outside the tube. With the increase of time interval, the peak sound pressure decreases and the total duration as well as the duration of the positive pressure increase. The synchronization of the working process of the dual-tube pulse detonation engine can be diagnosed by analyzing the pressure and duration of the sound wave outside the tube. The research results in this paper have certain reference significance for improving the synchronous of multi-tube pulse detonation engine and will be useful for the application of multi-tube pulse detonation engine in aircraft power system.
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