scholarly journals Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Jichao Hu ◽  
Juntao Chang ◽  
Lei Wang ◽  
Shibin Cao ◽  
Wen Bao
Keyword(s):  
Oscillatory Flow ◽  
Coupling Effect ◽  
The Other ◽  
Coupling Mechanism ◽  
Mechanism Analysis ◽  
Reversed Flow ◽  
Hypersonic Inlet ◽  
Scramjet Engine ◽  
Coupling Characteristic ◽  
Inlet Unstart

The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

Vibration of Bending-Torsion Coupled Resonance in a Rotor

2013 ◽  
Author(s):  
Hiroyuki Fujiwara ◽  
Tadashi Tsuji ◽  
Osami Matsushita
Keyword(s):  
Numerical Simulations ◽  
Natural Frequency ◽  
Torsional Vibration ◽  
Rotational Speed ◽  
Coupling Effect ◽  
The Other ◽  
Resonance Phenomenon ◽  
Horizontal Direction ◽  
Bending Vibration ◽  
Rotor Systems

In certain rotor systems, bending-torsion coupled resonance occurs when the rotational speed Ω (= 2π Ωrps) is equal to the sum/difference of the bending natural frequency ωb (= 2π fb) and torsional natural frequency ωθ(= 2πfθ). This coupling effect is due to an unbalance in the rotor. In order to clarify this phenomenon, an equation was derived for the motion of the bending-torsion coupled 2 DOF system, and this coupled resonance was verified by numerical simulations. In stability analyses of an undamped model, unstable rotational speed ranges were found to exist at about Ωrps = fb + fθ. The conditions for stability were also derived from an analysis of a damped model. In rotational simulations, bending-torsion coupled resonance vibration was found to occur at Ωrps = fb − fθ and fb + fθ. In addition, confirmation of this resonance phenomenon was shown by an experiment. When the rotor was excited in the horizontal direction at bending natural frequency, large torsional vibration appeared. On the other hand, when the rotor was excited by torsion at torsional natural frequency, large bending vibration appeared. Therefore, bending-torsion coupled resonance was confirmed.

Modal Analysis of Fluid-Structure Interaction in a Bent Pipeline

2016 ◽  
Author(s):  
Gudrun Mikota ◽  
Rainer Haas ◽  
Evgeny Lukachev
Keyword(s):  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Coupling Effect ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Coupling Mechanism ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Resonance Coupling ◽  
Measured Frequency Response

Fluid-structure interaction in a bent pipeline is investigated by modal methods. Measured frequency response functions between flow rate excitation and pressure response indicate a coupling effect near the third pipeline resonance. Using modal coordinates for the hydraulic and the mechanical subsystems, a two-degrees-of-freedom study of resonance coupling is carried out. An experimental modal analysis of the coupled hydraulic-mechanical system confirms the predicted resonance splitting; it illustrates the coupling mechanism and shows the relevant mechanical part. An analytical fluid-structure interaction model succeeds in reproducing the measured coupling effect. This model is also used for modification prediction; it demonstrates that an appropriate assembly of mass and damping on the pipeline can help to reduce hydraulic resonance amplitudes.

Control of the Flight Vehicle Cable over Wide Spectrum Radiation Effects Simulation Experiment Research

2012 ◽  
Vol 510 ◽  
pp. 141-146
Author(s):  
Yi Lv
Keyword(s):  
Radiation Effects ◽  
Coupling Effect ◽  
Wide Spectrum ◽  
Ultra Wideband ◽  
Vehicle Body ◽  
Coupling Mechanism ◽  
High Power Microwave ◽  
Control Order ◽  
And Control ◽  
Environment Performance

According to the aircraft is under complex work hard to electromagnetic environment performance analysis of the issue, a vehicle body and control lead in ultra-wideband high power microwave (UWS-HPM) under the irradiation of coupling effect and experimental study. Use back to lose signal simulator with the repetitive; the change control the length of the wire, radiation orientation, irradiation parts and other measures to make the experiment generality. The results of the study show that: aircraft in more than 25 kV/m of field UWS-HPM irradiation, interference and make its crash. Interference coupling mechanism is energy electromagnetic pulse through the control lead into the control box, and influence the formation of the control order. On the basis of experiment, this paper analyzes the interference with various factors coupling relation, which for electromagnetic protection equipment provides a theoretical basis.

Two-dimensional numerical study of vortex shedding regimes of oscillatory flow past two circular cylinders in side-by-side and tandem arrangements at low Reynolds numbers

2014 ◽  
Vol 751 ◽  
pp. 1-37 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Vortex Shedding ◽  
Oscillatory Flow ◽  
Flow Regimes ◽  
Reynolds Numbers ◽  
The Other ◽  
Circular Cylinders ◽  
Two Dimensional ◽  
Low Reynolds Numbers ◽  
Single Cylinder ◽  
Gap Ratio

AbstractOscillatory flow past two circular cylinders in side-by-side and tandem arrangements at low Reynolds numbers is simulated numerically by solving the two-dimensional Navier–Stokes (NS) equations using a finite-element method (FEM). The aim of this study is to identify the flow regimes of the two-cylinder system at different gap arrangements and Keulegan–Carpenter numbers (KC). Simulations are conducted at seven gap ratios $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}G$ ($G=L/D$ where $L$ is the cylinder-to-cylinder gap and $D$ the diameter of a cylinder) of 0.5, 1, 1.5, 2, 3, 4 and 5 and KC ranging from 1 to 12 with an interval of 0.25. The flow regimes that have been identified for oscillatory flow around a single cylinder are also observed in the two-cylinder system but with different flow patterns due to the interactions between the two cylinders. In the side-by-side arrangement, the vortex shedding from the gap between the two cylinders dominates when the gap ratio is small, resulting in the gap vortex shedding (GVS) regime, which is different from any of the flow regimes identified for a single cylinder. For intermediate gap ratios of 1.5 and 2 in the side-by-side arrangement, the vortex shedding mode from one side of each cylinder is not necessarily the same as that from the other side, forming a so-called combined flow regime. When the gap ratio between the two cylinders is sufficiently large, the vortex shedding from each cylinder is similar to that of a single cylinder. In the tandem arrangement, when the gap between the two cylinders is very small, the flow regimes are similar to that of a single cylinder. For large gap ratios in the tandem arrangement, the vortex shedding flows from the gap side of the two cylinders interact and those from the outer sides of the cylinders are less affected by the existence of the other cylinder and similar to that of a single cylinder. Strong interaction between the vortex shedding flows from the two cylinders makes the flow very irregular at large KC values for both side-by-side and tandem arrangements.

Numerical Analysis for Dynamic Characteristics of New Launcher with Coupled Rigid and Flexible Motion

2010 ◽  
Vol 34-35 ◽  
pp. 44-49 ◽  
Author(s):  
Ying Ze Wang
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
High Performance ◽  
Coupling Effect ◽  
The Other ◽  
Flexible Coupling ◽  
Simulation Based ◽  
Coupling Dynamic ◽  
Coupling Dynamic Model

This paper is concerned with an analysis of the dynamic characteristics of the high performance launcher—rarefaction wave gun(RAVEN) by numerical simulation. Based on its launch mechanism and launch structure, a rigid-flexible coupling dynamic model which considered the coupling effect between the flexible virbation of the launch barrel and the motion behaviors of the other parts of the RAVEN is established via a subsystems method. The actual motion of the projectile and inertial breech during the lauching are described by the interior ballistic equations of the RAVEN. The dynamic characterisitcs of RAVEN is illustrated by the numerical simulation about a small caliber launcher, and the interaction between launch barrel and the other parts is also studied.

scholarly journals A Novel Design of Rescue Capsule considering the Pressure Characteristics and Thermal Dynamic Response with Thermomechanical Coupling Action Subjected to Gas Explosion Load

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaowei Zhai ◽  
Shibo Wu ◽  
Kai Wang ◽  
Xiaokun Chen ◽  
Haitao Li
Keyword(s):  
Dynamic Response ◽  
Coal Mine ◽  
Coupling Effect ◽  
Design Method ◽  
Thermomechanical Coupling ◽  
Structural Safety ◽  
Coupling Mechanism ◽  
Gas Explosion ◽  
Explosion Load ◽  
Mine Rescue

To ensure the structural safety and reliability of coal mine rescue capsule in disastrous surroundings after gas explosion, in this paper, the thermomechanical coupling effect on a certain structure subjected to gas explosion was analyzed, and then a novel rescue capsule with a combination of radius and square features was designed according to the underground surroundings and relevant regulations on mine rescue devices. Foremost, the coupling mechanism of thermal-fluid-solid interaction between gas explosion shock wave and rescue capsule and the thermal dynamic response of the capsule subjected to explosion load of gas/air mixture was investigated and revealed by employing LS-DYNA. The variation laws and characteristics of stress field, displacement field, and temperature field of the capsule were analyzed based on the simulation results. Results show that the structural safety, tightness, and reliability of the capsule meet the requirements of the national safety regulations. The design method presented in this work provides a new thought for design of coal mine rescue capsule.

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