This paper presents a study on airworthiness of fuel system for an unmanned air vehicle. The presented contents consist of network modeling for analysis and flight test results on fuel system airworthiness. First, performance prediction of fuel system for unmanned air vehicle was achieved using software tool based on theoretical analysis and empirical data. And also flight tests were performed for

In the present study, the interaction effect by inter-rotor spacing of coaxial rotor blades in hovering and forward flight is studied by using a Reynolds-averaged Navier–Stokes CFD flow solver based on mixed meshes. The meshes were composed of unstructured near-body region and Cartesian off-body region. The flux-difference splitting scheme of Roe was used for computing inviscid fluxes on the near-body

During service, a turbine engine undergoes frequently dynamic operations. Because of the changes in mass flow, temperature, pressure, as well as the different reaction of the components of turbine to these changes, the turbine performances may vary significantly. It is critical to understand and quantify these variations to design and integrate the turbine to the engine. This paper presents a study

In the present study, numerical simulation was conducted to study both the internal and external flows of a fluidic oscillator in a quiescent environment and with a crossflow. Unsteady Reynolds-averaged Navier–Stokes analysis was used to evaluate the flow field. The blowing ratio was varied to understand the interaction between the free stream and the oscillating jet. Results for the time-averaged

Detached Eddy Simulation is used to study the interaction flowfields of a supersonic lateral jet penetrating into the crossflow of projectiles with cruciform or X-type fin configurations at \({\text{Ma}} = 0.3\) and \(\alpha = 0^\circ ,30^\circ \sim 60^\circ\). For \(\alpha = 0^\circ\), typical flow structures such as barrel shock, Mach disk and counter-rotating vortex pair(CVP) induced from the jet

The tangential injection flow commingled with the mainstream could be abstracted as mixing layer, and profound importance is attached to aero-optical reduction for film-cooling target-seeking vehicles in engineering application. Leveraging the in-house code based on explicit fifth-order Weighted Compact Nonlinear Scheme and ray-tracing method, the supersonic mixing layer is numerically simulated to

In space exploration missions, the spacecraft have limited computing resources. In particular, the communications environments for these spacecraft, whether in deep space or the cislunar region, are characterized by intermittent connectivity loss, long signal-propagation delay, and high bit-error rates between spacecraft and their ground stations. Delay-Tolerant Network (DTN) has been introduced to

The effects of flow structure and particle size in the secondary combustor of a ducted rocket on mixing are investigated using a two-phase large eddy simulation analysis. The corner recirculation zone and central recirculation area appear in the combustor. Vortexes are generated mainly by the axial inlet flow. The stretched eddies along the axial direction appear on the rear section of the combustor

Propellant sloshing is one of the potential sources of disturbance which affects the stability and structural integrity of space vehicles. In this study, using a small scale model of the first Korean lunar orbiter fuel tank, which is partially filled with liquid fuel, the dynamic lateral sloshing has been simulated by CFD analysis for various fill-levels. Spherical tank geometry was assumed, because

This paper proposes a new cooperative homing guidance to enhance the survivability of multiple anti-ship missiles against a high-value target such a frigate or a battleship when prior information on the target is unknown. In this paper, the survivability enhancement for the multiple anti-ship missiles against the battleship with no preliminary information on its current heading direction and weak spot

To ensure high-resolution image acquisition for a spaceborne parabolic synthetic aperture radar (SAR) antenna, an appropriate thermal design is important to minimize the thermal distortion of the antenna reflector in severe on-orbit thermal environments. This paper describes the results of a preliminary thermal design and the analysis of a carbon fiber reinforced plastic skin-based unfurlable parabolic

This study considers intermittent maneuver based on line-of-sight rate bounding to improve target observability for passive homing guidance. Target observability is critical for the performance of the target tracking filter and indirectly affects the guidance accuracy. This paper derives an observability measure associated with the Fisher information matrix for the adaptive intermittent maneuver strategy

An integrated guidance and control problem under state constraints is considered for terminal homing of missile engagement. The problem is formulated as a moderate-size convex optimization problem, which can be efficiently solved via existing techniques such as interior point methods or alternating direction method of multipliers. Two different formulations are presented, and their computation time

This study conducts an aeromechanics analysis of a modern lift-offset coaxial rotor in high-speed flight. A lift-offset coaxial rotor of the Sikorsky X2 technology demonstrator (X2TD) is considered for the present study. For the analyses of rotor performance, blade airloads, and hub vibratory loads, a rotorcraft comprehensive analysis code, CAMRAD II, is used. For the rotor performance analysis at

Multi-DOF flexible space robots play a significant role in the on-orbit service. The flexibility of the robots is mainly caused by the flexible links and some flexible drive elements in joints. The vibration generated by the component flexibility can affect the accuracy of control. In this paper, the dynamics and control issues of flexible-link flexible-joint (FLFJ) space robots considering joint friction

To address standoff target tracking using a fixed-wing UAV in unknown background wind, a wind estimation based on Unscented Kalman Filter (UKF) is proposed. In the paper, UAV dynamic model and target state estimation are constructed, and Lyapunov vector field guidance (LVFG) framework is introduced to achieve standoff target tracking. The unknown target state and wind dynamic model have seldom been

In this paper, environmental tests were conducted with a MEMS (micro-electro mechanical system) oscillator, which is known to be robust under harsh environmental conditions, and comparisons with the existing TCXO (temperature-controlled crystal oscillator) were conducted. And the results of the environmental tests of a GNSS receiver equipped with the MEMS oscillator were compared with the test results

Target tracking using pseudo-measurement is widely used because of its simple implementation and computational advantages despite biased behavior. The biasedness of the pseudo-measurement tracking filter originates from a measurement-dependent Kalman gain and a state-dependent non-Gaussian biased noise. This paper proposes a bias-compensated pseudo-measurement filter considering a range rate measurement

Super-resolution reconstruction refers to the technique of reconstructing a high-resolution image from a single or a series of low-resolution images by digital image processing. This technology can not only increase the high-frequency information of the image, but also eliminate the low-resolution. Deep Learning has made breakthroughs in modern digital image processing. Compared to traditional algorithms

This paper intends to compare the effect of the attitude parameterization method on the performance of the attitude controller designed with the direct feedback of corresponding attitude states. To achieve this, the proportional-derivative controllers using the finite rotation angles and the modified Rodrigues parameters are designed with the same structure and equivalent performance of the direct

The flow field structure of a single injection port fluidic thrust vectoring nozzle was studied by introducing secondary flow injection in the expansion section of the two-dimensional convergent-divergent nozzle. To determine the motion characteristics of unsteady flow in a shock-induced fluidic vectoring nozzle, detached eddy simulation was conducted to simulate the three-dimensional flow field, and

The noise sources of the tip-jet driven rotor are mainly classified as rotor blade noise and jet noise. The rotor blade noise includes thickness noise, loading noise, and nonlinear quadrupole noise, while the jet noise includes nozzle momentum noise and jet radiation noise. Each noise component has different noise source mechanisms related to flow characteristics and the rotating motion. Especially

This paper proposes generalized polynomial guidance for controlling the terminal velocity vector (speed and flight path angle), which could be critical for the effectiveness of the warhead of tactical ballistic missiles. A polynomial reference trajectory satisfying the initial and terminal altitudes and flight path angles is introduced with a guidance parameter that can be chosen to change the terminal

This study proposes an algorithm to calculate fast the predicted intercept point (PIP) of the anti-ballistic missile system. A neural network system is trained to learn the motion of the ballistic target to predict the future target position. Then a prediction algorithm iteratively calculates PIP and the launch time of the interceptor. PIP calculation enables the missile to effectively approach to

An Improved Delayed Detached Eddy Simulation (IDDES) model as a kind of hybrid RANS/LES approach has been developed and applied to calculate tip leakage flow in a linear compressor cascade with moving casing, and the result was compared with the experimental results and LES results. The hybrid approach combines delayed detached eddy simulation (DDES) with an improved RANS–LES hybrid model aimed at