Advanced Materials Research Vol. 1016

Abstract: An airdrop model with aerial carrier is carried out to simulate an airdrop test. A coupled CFD/6 DOF is designed to compute the orientation and trajectory of the airdrop model. The results show that the CFD/6 DOF coupled method is appropriate to simulate this problem with a sufficient precision. The airdrop’s motion is strongly coupled with the aerodynamic force after leaving the sliding rail and the trajectory of its CG is mainly in the symmetry of the aerial carrier. The variation of its orientation mainly rolls in X axis direction and it swings as an approximate periodic oscillation which amplitude decreases over time. The maximum angle of orientation in X axis direction is-116°in 5 seconds. The similar variation of the airdrop motion is present in different angle of attack and sideslip of the aerial carrier.

Abstract: Refer to the characteristics of BVR air combat and multi-target attack for the Fourth Generation Fighters, this paper constructs and computes the model of probability distributions in multi-target kill zone, the model of the best attack path/attack position of multi-target attack. The model of probability distributions in multi-target kill zone considers heading angle and approaching angle of target, distance between fighter and target, maximum off-boresight launching angle and killing angle. The model of the best attack path/attack position considers damage probability to targets by missiles, threat degree to fighter of targets, and threat degree to fighter of residual targets. The paper calculates the simulation data according to the models, analyzes probability distributions in multi-target kill zone of missiles, the best attack path/attack position. The models and simulated results show that the method, which uses kill zone probability model, can improve the damage probability and reduce threat degree from enemy targets.

Abstract: A new aero-engine gas path fault monitoring technology is presented in this paper, which is based on the capacitive sensor. The working conditions of the aero-engine gas path components can be monitored through the sensor, which is the main source of the aero-engine faults such as the gas path debris. The capacitive sensor has advantages of non-contact measurement, high sensitivity and simple structure, which can effectively solve the problems of the traditional aero-engine gas path fault diagnosis technology, such as the poor operability, the weak real-time performance and the high cost. Through the analysis of the capacitive sensor model, the feasibility of the capacitive sensor in the aero-engine gas path fault monitoring is verified.

Abstract: The electronic systems of aerospace techniques include power microwave devices and analog and digital semiconductor devices. The radiation of power microwave devices may effect on the semiconductor devices. So it’s necessary to know the electromagnetic effects of this radiation on the semiconductor devices. The electromagetic effects of the microwave radiation exposure on the semiconductor diodes, the main part of any semiconductor devices, are considered. The changes of current – voltage characteristics of the diodes are explained, outgoing from the model of the recombination of carriers through deep energy level recombination center in forbidden gap induced by microwave radiation field.

Abstract: Traffic is a major source of environmental noise in modern society. Subsequently, the development of new vehicles is subjected to heavy governmental legislations. The major noise source on common road vehicles during acceleration is the flow noise caused by turbulent exhaust gas. The main goal of this work is to develop an appropriate Aeroacoustic simulation method to investigate the acoustic of sound on exhaust automotive muffler. The range of validity of the method is studied comparing results to experimental data. The Computational Aeroacoustics (CAA) results are compared with an experimental test in a vehicle during its acceleration and the mean flow model of the muffler has a satisfactory mesh with a suitable inlet boundary provided by an engine dynamometer data. The present work describes a good agreement between computational and experimental approach for the Aeroacoustics behavior of a specific configuration of exhaust muffler.

Abstract: Two efficient computational procedures based on the boundary layer equations and approximate relations areassessedin prediction of the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. For the boundary layer procedure, the boundary layer equationsutilize the integral matrix solution algorithm for the blunt nose and after body region by using a space marching technique. The integral matrix procedure able us to create accurate and smooth results using the minimum grid in the boundary layer and minimize the computational costs. Applying the approximate method creates a robust and efficient code for heating calculations over the blunt bodies which flies in hypersonic regimes. These algorithms are highly appropriate to design of hypersonic reentry vehicles. The effects of real gas on the flowfield characteristics are also studied in two procedures.

Abstract: Computational study is carried out in radial and 200 backward swept diverging channels rotating about the axial direction. Centrifugal and Coriolis forces, which are developed due to the rotation, affect the secondary flows and flow pattern inside the channel. Reynolds number of Re=36000 with Rotation numbers ranging from 0.0 and 1.5 are chosen for investigation. The variation of velocity and turbulence kinetic energy is studied at several locations of the curved channels. Positive Richardson numbers on the suction side indicates stabilizations of the flow. The stabilization effect increases with increasing Rotation numbers at both the channels.

Abstract: Unsteady, pressure driven in the gap between two parallel plates flow of two non-Newtonian incompressible second grade fluids is considered. The governing equations are established for the particular two-layer flow and analytical solutions of the equations that satisfy the imposed boundary conditions are obtained. The velocity of each fluid is expressed as function of the material constants, time dependent pressure gradient and other characteristics of the fluids. As part of the solution, an expression for the interface velocity is derived. We analyze the shift of the velocity maximum from one to another fluid as a function of variety of values of fluids’ parameters.

Abstract: In Thailand, the average wind speed is generally quite low (≈ 3 - 4 m/s). Although Vertical Axis Wind Turbines (VAWTs) are designed for low speed wind, standalone VAWTs are still unable to generate power satisfactorily under that practical condition. This study introduces a new design of a wind flow controlling device, called a “wind booster”, by utilizing Computational Fluid Dynamics (CFD). A wind booster is developed for incorporating with a VAWT in order to increase the performance of the VAWT and to overcome the limitation of harvesting energy with low availability at low speed wind. The guiding and throttling effects of the optimal design of the wind booster are able to increase the angular velocity of VAWTs which leads to an increase in power generated from VAWTs.

Abstract: The Martian dust is a serious threat to the spacecraft and rover. It would hinder the functioning of equipment and limit mission duration. The paper introduces a system, which uses supersonic gas jet formed by a Laval nozzle to blow off the accumulated dust. The related parameters have been investigated and the flow fluid field has been simulated.