scholarly journals Research on control effectiveness of fluidic thrust vectoring

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042199813
Author(s):  
Fei Xue ◽  
Gu Yunsong ◽  
Yuchao Wang ◽  
Han Qin
Keyword(s):  
High Altitude ◽  
Ground State ◽  
Deflection Angle ◽  
Internal Flow ◽  
Lateral Force ◽  
Control Surface ◽  
Low Density ◽  
Thrust Vectoring ◽  
Density State ◽  
Fluidic Thrust Vectoring

In view of the control effects of fluidic thrust vector technology for low-speed aircraft at high altitude/low density and low altitude/high density are studied. The S-A model of FLUENT software is used to simulate the flow field inside and outside the nozzle with variable control surface parameters, and the relationship between the area of control surface and the deflection effect of main flow at different altitudes is obtained. It is found that the fluidic thrust vectoring nozzle can effectively control the internal flow in the ground state and the high altitude/low density state. and the mainstream deflection angle can be continuously adjusted. The maximum deflection angle of the flow in the ground state is 21.86°, and the maximum deviation angle of the 20 km high altitude/low density state is 18.80°. The deflecting of the inner flow of the nozzle is beneficial to provide more lateral force and lateral torque for the aircraft. The high altitude/low density state is taken as an example. When the internal flow deflects 18.80°, the lateral force is 0.32 times the main thrust. For aircraft with high altitude and low density, sufficient lateral and lateral torque can make the flying aircraft more flexible, which can make up the shortcomings of the conventional rudder failure and even replace the conventional rudder surface.

Coanda Surface Geometry Optimization for Multi-Directional Co-Flow Fluidic Thrust Vectoring

2009 ◽  
Author(s):  
Fariborz Saghafi ◽  
Afshin Banazadeh
Keyword(s):  
Deflection Angle ◽  
Flow Characteristics ◽  
Geometric Parameters ◽  
Nozzle Geometry ◽  
Surface Geometry ◽  
Thrust Vectoring ◽  
Affective Factors ◽  
Optimization Parameters ◽  
Fluidic Thrust Vectoring ◽  
Maximum Thrust

The performance of Co-flow fluidic thrust vectoring is a function of secondary flow characteristics and the fluidic nozzle geometry. In terms of nozzle geometry, wall shape and the secondary slot aspect ratio are the main parameters that control the vector angle. The present study aims to find a high quality wall shape to achieve the best thrust vectoring performance, which is characterized by the maximum thrust deflection angle with respect to the injected secondary air. A 3D computational fluid dynamics (CFD) model is employed to investigate the flow characteristics in thrust vectoring system. This model is validated using experimental data collected from the deflection of exhaust gases of a small jet-engine integrated with a multi-directional fluidic nozzle. The nozzle geometry is defined by the collar radius and its cutoff angle. In order to find the best value of these two parameters, Quasi-Newton optimization method is utilized for a constant relative jet momentum rate, a constant secondary slot height and insignificant step size. In this method, the performance index is described as a function of thrust deflection angle. Optimization parameters (wall geometric parameters) are estimated in the direction of gradient, with an appropriate step length, in every iteration process. A good guess of initial optimization parameters could lead to a rapid convergence towards an optimal geometry and hence maximum thrust deflection angle. Examination over a range of geometric parameters around the optimum point reveals that this method promises the best performance of the system and has potential to be employed for all the other affective factors.

A Survey of Fluidic Thrust Vectoring Nozzle by Numerical Analysis

2013 ◽  
Vol 423-426 ◽  
pp. 1685-1688
Author(s):  
Li Li ◽  
Zhi Hui Shi ◽  
Tsutomu Saito
Keyword(s):  
Deflection Angle ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Injection Pressure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Thrust Vectoring ◽  
Numerical Investigations ◽  
The Deflection Angle ◽  
Fluidic Thrust Vectoring

Numerical investigations are conducted to simulate the flow field of a 2D converging-diverging nozzle, for fluidic thrust vectoring. The numerical simulation of nozzle flow is carried out with Navier-Stokes equations model. Simulations are done with different primary and secondary jet conditions. The numerical results show that the smaller of the distance between secondary jet and exit, the larger is the thrust deflection angle. As the injection pressure ratio increases, the deflection angle increases followed on the premise of not far between secondary jet port and exit. The parameters play important roles on thrust vectoring capability.

Effect of Variations in Weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft

1955 ◽  
Vol 59 (534) ◽  
pp. 435-437
Author(s):  
P. L. Sutcliffe
Keyword(s):  
High Altitude ◽  
Normal Force ◽  
Control Surface ◽  
Military Aircraft ◽  
Longitudinal Control ◽  
The Past ◽  
Normal Acceleration

The ability to manoeuvre at high altitude has become one of the main requirements in the design of modern military aircraft. Ability to manoeuvre enables the fighter pilot to execute tight turns during the attack on a bomber and the bomber pilot to perform evasive manoeuvres and so make the task of the fighter more difficult.Normally the main manoeuvre considered is the application of increased normal acceleration, or g, and if we assume that (a) there is sufficient pitching power available from the longitudinal control surface to increase the wing incidence to give the necessary increase in normal force, and (b) that the new wing incidence is below the stalling incidence of the wing, then the degree of manoeuvrability available is a function of thrust and drag alone. In the past the manoeuvrability required at a given altitude has been expressed in terms of the rate of climb available at that altitude and thus we have such definitions as “ the 1,000 ft./min. ceiling ” and so on.

Effect of Control Parameters of Secondary Jet on Fluidic Thrust Vectoring

2014 ◽  
Vol 998-999 ◽  
pp. 613-616
Author(s):  
Li Li ◽  
Dong Ping Wang ◽  
Tsutomu Saito
Keyword(s):  
Flow Field ◽  
Control Parameters ◽  
Jet Injection ◽  
Specific Design ◽  
Initial State ◽  
Thrust Vectoring ◽  
Original Hypothesis ◽  
Fluidic Thrust Vectoring

The flow field was simulated in a 2D convergent-divergent nozzle, for fluidic thrust vectoring with N-S method. Based on the specific design, the effects of control parameters of secondary jet injection is investigated, and a method is proposed to calculate the initial state of secondary jet, which is different from original hypothesis of stagnation. The results showed that the two methods have closed results and the stagnation hypothesis is suitable for the calculation of the initial state of secondary jet.

Effect of predation on the low-density dynamics of vendace: significance of the functional response

2001 ◽  
Vol 58 (10) ◽  
pp. 1909-1923 ◽  
Author(s):  
Outi Heikinheimo
Keyword(s):  
Functional Response ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Dynamic Modelling ◽  
Perca Fluviatilis ◽  
Low Density ◽  
Functional Responses ◽  
Density State ◽  
Brown Trout Salmo Trutta ◽  
Stock Recruitment

During the past 20 years, there have been prolonged vendace (Coregonus albula) recessions in several Finnish lakes. Hypotheses have been proposed that predation by brown trout (Salmo trutta m. lacustris) or perch (Perca fluviatilis) on young-of-the-year vendace could prevent the recovery of the vendace stocks from a low-density state. In this study, dynamic modelling was applied to examine the effect of predation, assuming a dome-shaped spawning stock–recruitment relationship for vendace, type II or III functional responses to predation by brown trout and perch, and a constant rate of fishing. The results showed that the form of the functional response is crucial in determining the significance of the predation on vendace stocks that have a steep dome-shaped stock–recruitment relationship. In all cases, however, predation by perch had more effect than that by brown trout, probably due to perch occupying the pelagic zone when the vendace stock is sparse. This may make the mortality of vendace increase with decreasing population density (depensatory mortality) at certain density levels.

scholarly journals Backstepping Fault-Tolerant Control for Unmanned Thrust-Vectoring Aircraft Based on Sliding-Mode Observer

2018 ◽  
Vol 36 (5) ◽  
pp. 978-987
Author(s):  
Bingqian Li ◽  
Wenhan Dong ◽  
Xiaoshan Ma
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
Fault Tolerant Control ◽  
Surface Damage ◽  
Sliding Mode Observer ◽  
Control Surface ◽  
Actuator Faults ◽  
Thrust Vectoring ◽  
Fault Parameters ◽  
Uncertainty Control

In this paper, a backstepping fault-tolerant control based on sliding-mode observer is proposed for the unmanned thrust-vectoring aircraft (UTVA) control. First, the UTVA model with the uncertainty, control surface damage and actuator faults is described, which is divided into fast loop and slow loop. Next, the cascade observers including a high-order SMO and the discontinuous projection adaptive law are proposed to estimate the states with compensating the uncertainty and control surface damage, and the sliding-mode observer is designed to identify actuator faults and estimate fault parameters. Then, the backstepping fault-tolerant control combining the estimation of states and fault parameters is proposed to achieve the global fault-tolerant control, which compensates the uncertainty, control surface damage and actuator faults. Finally, simulation results are given to demonstrate the effectiveness for UTVA.

scholarly journals Tumor-Derived Factors Differentially Affect the Recruitment and Plasticity of Neutrophils

Cancers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 5082
Author(s):  
Ludovica Arpinati ◽  
Naomi Kaisar-Iluz ◽  
Merav E. Shaul ◽  
Christopher Groth ◽  
Viktor Umansky ◽  
...  
Keyword(s):  
Cancer Biology ◽  
Ex Vivo ◽  
Surface Marker ◽  
Normal Density ◽  
Low Density ◽  
Ros Production ◽  
Surface Marker Expression ◽  
Density State ◽  
Surface Receptor

Neutrophils play a key role in cancer biology. In contrast to circulating normal-density neutrophils (NDN), the amount of low-density neutrophils (LDN) significantly increases with tumor progression. The correlation between these neutrophil subpopulations and intratumoral neutrophils (TANs) is still under debate. Using 4T1 (breast) and AB12 (mesothelioma) tumor models, we aimed to elucidate the source of TANs and to assess the mechanisms driving neutrophils’ plasticity in cancer. Both NDN and LDN were found to migrate in response to CXCL1 and CXCL2 exposure, and co-infiltrate the tumor site ex vivo and in vivo, although LDN migration into the tumor was higher than NDN. Tumor-derived factors and chemokines, particularly CXCL1, were found to drive neutrophil phenotypical plasticity, inducing NDN to transition towards a low-density state (LD-NDN). LD-NDN appeared to differ from NDN by displaying a phenotypical profile similar to LDN in terms of nuclear morphology, surface receptor markers, decreased phagocytic abilities, and increased ROS production. Interestingly, all three subpopulations displayed comparable cytotoxic abilities towards tumor cells. Our data suggest that TANs originate from both LDN and NDN, and that a portion of LDN derives from NDN undergoing phenotypical changes. NDN plasticity resulted in a change in surface marker expression and functional activity, gaining characteristics of LDN.

scholarly journals X-ray studies of the transformation from high- to low-density amorphous water

2019 ◽  
Vol 377 (2146) ◽  
pp. 20180164 ◽  
Author(s):  
Daniel Mariedahl ◽  
Fivos Perakis ◽  
Alexander Späh ◽  
Harshad Pathak ◽  
Kyung Hwan Kim ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Structural Evolution ◽  
High Energy ◽  
Real Space ◽  
High Density ◽  
Low Density ◽  
X Ray ◽  
Amorphous Ice ◽  
Density State ◽  
Amorphous States

Here we report about the structural evolution during the conversion from high-density amorphous ices at ambient pressure to the low-density state. Using high-energy X-ray diffraction, we have monitored the transformation by following in reciprocal space the structure factor S OO ( Q ) and derived in real space the pair distribution function g OO ( r ). Heating equilibrated high-density amorphous ice (eHDA) at a fast rate (4 K min –1 ), the transition to the low-density form occurs very rapidly, while domains of both high- and low-density coexist. On the other hand, the transition in the case of unannealed HDA (uHDA) and very-high-density amorphous ice is more complex and of continuous nature. The direct comparison of eHDA and uHDA indicates that the molecular structure of uHDA contains a larger amount of tetrahedral motives. The different crystallization behaviour of the derived low-density amorphous states is interpreted as emanating from increased tetrahedral coordination present in uHDA. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.

Lattice-Boltzmann Very Large Eddy Simulations of Fluidic Thrust Vectoring in a Converging/Diverging Nozzle

2020 ◽  
Author(s):  
Avinash Jammalamadaka ◽  
Gregory M. Laskowski ◽  
Yanbing Li ◽  
James Kopriva ◽  
Pradeep Gopalakrishnan ◽  
...  
Keyword(s):  
Lattice Boltzmann ◽  
Large Eddy Simulations ◽  
Thrust Vectoring ◽  
Large Eddy ◽  
Fluidic Thrust Vectoring
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