Characteristics of PZT-driven dual synthetic jets actuator and numerical simulations of thrust vectoring

2010 ◽  
Author(s):  
Zhen-bing Luo ◽  
Lin Wang ◽  
Deng-pan Wang ◽  
Zhi-xun Xia
Keyword(s):  
Numerical Simulations ◽  
Synthetic Jets ◽  
Thrust Vectoring

scholarly journals Numerical simulations of synthetic jets in aerodynamic applications

2014 ◽  
Vol 6 (Special 1) ◽  
pp. 81-93 ◽  
Author(s):  
MACOVEI Alexandru Catalin ◽  
◽  
FRUNZULICA Florin
Keyword(s):  
Numerical Simulations ◽  
Synthetic Jets

scholarly journals Effects of Cavity on the Performance of Dual Throat Nozzle During the Thrust-Vectoring Starting Transient Process

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Rui Gu ◽  
Jinglei Xu
Keyword(s):  
Numerical Simulations ◽  
Transient Process ◽  
Dynamic Loads ◽  
Challenging Problem ◽  
Excellent Performance ◽  
Thrust Vectoring ◽  
Process Dynamic ◽  
Parameter Variations ◽  
Starting Process ◽  
And Control

The dual throat nozzle (DTN) technique is capable to achieve higher thrust-vectoring efficiencies than other fluidic techniques, without compromising thrust efficiency significantly during vectoring operation. The excellent performance of the DTN is mainly due to the concaved cavity. In this paper, two DTNs of different scales have been investigated by unsteady numerical simulations to compare the parameter variations and study the effects of cavity during the vector starting process. The results remind us that during the vector starting process, dynamic loads may be generated, which is a potentially challenging problem for the aircraft trim and control.

Numerical Simulations of Mixing Enhancement in Subsonic Jet Using High-Momentum Synthetic Jets

2016 ◽  
Vol 32 (5) ◽  
pp. 1095-1103 ◽  
Author(s):  
Qitai Eri ◽  
Liang Hong ◽  
Ting Li ◽  
Qiang Wang ◽  
Mengjie Wang
Keyword(s):  
Numerical Simulations ◽  
Synthetic Jets ◽  
Mixing Enhancement ◽  
High Momentum ◽  
Subsonic Jet

scholarly journals Investigation of an Underwater Vectored Thruster Based on 3RPS Parallel Manipulator

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Tao Liu ◽  
Yuli Hu ◽  
Hui Xu ◽  
Mohamed El Ghami
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Parallel Manipulator ◽  
Driving Forces ◽  
Autonomous Underwater Vehicles ◽  
Affecting Factors ◽  
Compact Structure ◽  
Thrust Vectoring ◽  
Pid Algorithm ◽  
Control Scheme

Autonomous underwater vehicles (AUVs) are important and useful tool platforms in exploring and utilizing ocean resource. However, the effect of control surfaces would decrease even invalid complete in this condition, and it is very hard for conventional AUVs to perform detailed missions at a low forward speed. Therefore, solving this problem of AUVs becomes particularly important to increase the application scope of AUVs. In this paper, we present a design scheme for the vectored thruster AUV based on 3RPS parallel manipulator, which is a kind of parallel manipulator and has advantages of compact structure and reliable performance. To study the performance and characteristics of the proposed thrust-vectoring mechanism, a series of works about corresponding kinematic and dynamic analysis have been performed through the theoretical analysis and numerical simulation. In the part of kinematics, the inverse, forward kinematics, and workspace analysis of the thrust-vectoring mechanism is presented, and the numerical simulations are accomplished to prove the feasibility and effectiveness of this design in AUVs. In order to further verify feasibility of the thrust-vectoring mechanism, based on the considerations of various affecting factors, a dynamic model of the designed thrust-vectoring mechanism is established according to theoretical analysis, and the driving forces of the linear actuator are presented through a series of numerical simulations. In addition, a control scheme based on PID algorithm is proposed for the designed vectored thruster with considering various affecting factors and the application environment. Meanwhile, the control scheme is also established and verified in MATLAB Simscape Mutibody. A series of numerical simulations of the thrust-vectoring mechanism prove the feasibility of the vectored thruster. According to equipping the designed vectored thruster, the AUVs can overcome the limit of weakening the control ability at zero or low forward speeds, and this improvement also expands the application of it, which has been scaled greatly.

LUO-XIA MODEL AND NUMERICAL SIMULATIONS OF DUAL SYNTHETIC JETS

2011 ◽  
pp. 1006-1013
Author(s):  
Z. B. LUO ◽  
Z. X. XIA ◽  
L. WANG ◽  
B. LIU ◽  
Q. H. ZENG
Keyword(s):  
Numerical Simulations ◽  
Synthetic Jets

Experimental and numerical investigation of an axisymmetric divergent dual throat nozzle

2019 ◽  
Vol 234 (3) ◽  
pp. 563-572 ◽  
Author(s):  
Yang-Sheng Wang ◽  
Jing-Lei Xu ◽  
Shuai Huang ◽  
Yong-Chen Lin ◽  
Jing-Jing Jiang
Keyword(s):  
Numerical Simulations ◽  
Skin Friction ◽  
Flow Structure ◽  
Static Pressure ◽  
Three Dimensional ◽  
Computational Domain ◽  
Thrust Vectoring ◽  
Separation Line ◽  
Pressure Distributions ◽  
Actual Flow

The dual throat nozzle achieves higher thrust vectoring efficiencies and lesser thrust loss than other fluidic thrust-vectoring nozzles. Separation always occurs at the bottom of the cavity with complex three-dimensional characteristics for the dual throat nozzle. In this paper, by comparing the flow structure, nozzle surface static pressure distributions and skin friction lines, which are obtained by numerical simulations and wind tunnel experiments, an axisymmetric divergent dual throat nozzle is investigated in detail. The main results show the following findings. (1) The experimental schlieren photographs confirm again that the divergent nozzle configuration has the starting problem from an intuitive perspective. Meanwhile, the flow structure and nozzle surface static pressure distributions obtained by numerical simulations are consistent with the experimental results, except for the low nozzle pressure ratios. (2) The circumferential pressure difference is negligible upstream of the separation line but obvious downstream of the separation line. The skin friction lines and nozzle surface static pressure distributions of different circumferential angles obtained by experiments both prove that the actual flow in the axisymmetric divergent dual throat nozzle indeed possesses three-dimensional characteristics. Therefore, it is necessary to utilize the full three-dimensional computational domain to study the complex three-dimensional characteristics of the flow for the axisymmetric divergent dual throat nozzle thoroughly.

A Computational and Analytical Study into the Use of Counter-Flow Fluidic Thrust Vectoring Nozzle for Small Gas Turbine Engines

2014 ◽  
Vol 629 ◽  
pp. 97-103
Author(s):  
Afshin Banazadeh ◽  
Farzad Banazadeh
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Computational Simulation ◽  
Pressure Coefficient ◽  
Nozzle Geometry ◽  
Mathematical Form ◽  
Counter Flow ◽  
Thrust Vectoring ◽  
Fluidic Thrust Vectoring

This paper provides an understanding of counter-flow fluidic thrust vectoring, in the presence of the secondary air vacuum, applied to the exhaust nozzle of a micro-jet engine. An analytical and numerical study is performed here on a divergent collar surface adjacent to the cylindrical exhaust duct system. The vectoring angle is controlled by manipulating the momentum flux through a vacuum gap that is located on a circle concentric to the main nozzle. Three dimensional numerical simulations are conducted by utilizing a computational fluid dynamics model with two-equation standard k-ε turbulence model to study the pressure and velocity distribution of internal flow and nozzle geometry. Moreover, an analytical validation is carried out based on the known mathematical form of the governing equations of fluid dynamics over the sinusoidal wall. It is shown that the analytical results are in good agreement with numerical simulations, which also show that the pressure coefficient over the collar surface has the same trend as given by computational simulation. Similarly, the results of the numerical method are also verified against experimental results that were approved by previous research in area of numerical model for co-flow fluidic thrust vectoring technique.

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

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