Performance sensitivity of hypersonic vehicles to changes of angle of attack and dynamic pressure

1989 ◽  
Keyword(s):  
Dynamic Pressure ◽  
Angle Of Attack ◽  
Hypersonic Vehicles ◽  
Performance Sensitivity

scholarly journals Development and Application of Computational Tool Using Local Surface Inclination Methods for Preliminary Analysis of Hypersonic Vehicles

2020 ◽  
Author(s):  
Tiago Cavalcanti Rolim ◽  
Sheila Cristina Cintra ◽  
Marcela Marques da Cruz Pellegrini
Keyword(s):  
Preliminary Analysis ◽  
Aerodynamic Force ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Hypersonic Vehicles ◽  
Computational Tool ◽  
Local Surface ◽  
Force Coefficients ◽  
Surface Inclination

This work presents a computational tool for preliminary analysis of hypersonic vehicles, based on local surface inclination methods: the HipeX. This program was developed for reading standard triangulation language (STL) geometry files and calculating pressure coefficient and temperature distributions over vehicle’s surface using the Newtonian, modified Newtonian or tangent-wedge methods. Validations were made with a cylinder and a sphere, where only the Newtonian method was applied, and with experimental data from Apollo capsule at Mach 10, where the Newtonian and the modified Newtonian methods were applied. These validations presented the code capability to read geometries as well as to estimate aerodynamic force coefficients. A preliminary application was to predict the aerodynamic force coefficients of a generic hypersonic vehicle over constant dynamic pressure trajectories of 23,940, 60,000 and 95,760 N/m2 with zero angle of attack. With a fixed dynamic pressure of 60,000 N/m2, this vehicle was tested over several Mach numbers and with angle of attack variation from -10 to 10 deg. Zero angle of attack investigation showed minor changes on the force coefficients with altitude, while the variation of angle of attack produced more pronounced variations on these parameters. Maximum flow temperatures over vehicle’s surface were estimated ranging from 850 to 5,315 K.

The Effect of Structural Parameters on Response Characteristics of Aeroelastic System in the Presence of Dynamic Stall

2021 ◽  
Author(s):  
Zhan Qiu ◽  
Fuxin Wang
Keyword(s):  
Limit Cycle ◽  
Structural Parameters ◽  
Dynamic Pressure ◽  
Angle Of Attack ◽  
Dynamic Stall ◽  
System Response ◽  
Structural Stiffness ◽  
Aeroelastic System ◽  
Equilibrium Angle ◽  
Minimum Angle

Abstract The effect of structural paramters on the response and aerodynamic stiffness characteristics of the free aeroelastic system under the influence of dynamic stall is investigated adopting CFD (Computational Fluid Dynamics) method. The equilibrium angle of the spring and the structural stiffness are taken as parameters of interest. Systems with small equilibrium angles enter the symmetric limit-cycle state more quickly after a Hopf bifurcation and experience dynamic stall in both directions, rather than slowly decreasing in minimum angle of attack and remaining in the asymmetric limit-cycle state before dynamic stall in the opposite direction, as is the case with systems with large spring equilibrium angles. Thus, aerodynamic stiffness of system with large equilibrium angles can be more significantly influenced by the change in aerodynamic moment characteristics at the minimum angle of attack. Furthermore, by increasing the initial angular velocity, we find that the system response all becomes symmetric limit cycle and therefore the aerodynamic stiffness appears to have a monotonically increasing characteristic. As to the effect of structural stiffness, it is found that the limit cycle amplitude first increases with structural stiffness after bifurcation, then the amplitude is unchanged with varying structural stiffness at higher Mach number. Energy maps show that the parametric distribution of the energy transfer contributes to this phenomenon. Moreover, when entering the symmetric limit cycle state, the structural stiffness no longer has a significant effect on the aerodynamic stiffness of the system, as the increase in the aerodynamic stiffness is determined solely by the increase in dynamic pressure without the effect of changes in moment characteristics.

scholarly journals Techniques for the Determination of Local Dynamic Pressure and Angle of Attack on a Horizontal Axis Wind Turbine

10.2172/61151 ◽  
1995 ◽  
Author(s):  
Derek E. Shipley ◽  
Mark S. Miller ◽  
Michael C. Robinson ◽  
Marvin W. Luttges ◽  
David A. Simms
Keyword(s):  
Wind Turbine ◽  
Dynamic Pressure ◽  
Angle Of Attack ◽  
Horizontal Axis ◽  
Local Dynamic ◽  
Horizontal Axis Wind Turbine

scholarly journals Estimation of Airspeed, Angle of Attack, and Sideslip for Small Unmanned Aerial Vehicles (UAVs) Using a Micro-Pitot Tube

Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2325
Author(s):  
Gennaro Ariante ◽  
Salvatore Ponte ◽  
Umberto Papa ◽  
Giuseppe Del Core
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Pressure Sensor ◽  
Dynamic Pressure ◽  
Estimation Error ◽  
Angle Of Attack ◽  
Noise Removal ◽  
Unmanned Aircraft ◽  
Pitot Tube ◽  
Measurement Unit ◽  
Aerial Vehicles

Fixed and rotary-wing unmanned aircraft systems (UASs), originally developed for military purposes, have widely spread in scientific, civilian, commercial, and recreational applications. Among the most interesting and challenging aspects of small UAS technology are endurance enhancement and autonomous flight; i.e., mission management and control. This paper proposes a practical method for estimation of true and calibrated airspeed, Angle of Attack (AOA), and Angle of Sideslip (AOS) for small unmanned aerial vehicles (UAVs, up to 20 kg mass, 1200 ft altitude above ground level, and airspeed of up to 100 knots) or light aircraft, for which weight, size, cost, and power-consumption requirements do not allow solutions used in large airplanes (typically, arrays of multi-hole Pitot probes). The sensors used in this research were a static and dynamic pressure sensor (“micro-Pitot tube” MPX2010DP differential pressure sensor) and a 10 degrees of freedom (DoF) inertial measurement unit (IMU) for attitude determination. Kalman and complementary filtering were applied for measurement noise removal and data fusion, respectively, achieving global exponential stability of the estimation error. The methodology was tested using experimental data from a prototype of the devised sensor suite, in various indoor-acquisition campaigns and laboratory tests under controlled conditions. AOA and AOS estimates were validated via correlation between the AOA measured by the micro-Pitot and vertical accelerometer measurements, since lift force can be modeled as a linear function of AOA in normal flight. The results confirmed the validity of the proposed approach, which could have interesting applications in energy-harvesting techniques.

Horizontal tail local angle-of-attack and total pressure measurements through static pressure ports and Kiel pitot

2019 ◽  
Vol 123 (1268) ◽  
pp. 1476-1491
Author(s):  
R. M. Granzoto ◽  
L. A. Algodoal ◽  
G. J. Zambrano ◽  
G. G. Becker
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Dynamic Pressure ◽  
Angle Of Attack ◽  
Flight Test ◽  
Vertical Position ◽  
Local Dynamic ◽  
Pressure Measurements ◽  
Turbofan Engines ◽  
Local Angle

ABSTRACTAircraft handling qualities may be influenced by wing-tip flow separations and horizontal tail (HT) reduced efficiency caused by loss of local dynamic pressure or local tailplane flow separations in high angle-of-attack manoeuvres. From the flight tester’s perspective, provided that the test aircraft presents sufficient longitudinal control authority to overcome an uncommanded nose-up motion, this characteristic should not be a safety factor. Monitoring and measuring the local airflow in the aircraft’s HT provides information for safe flight-test envelope expansion and data for early aerodynamic knowledge and model validation. This work presents the development, installation and pre-flight calibration using computational fluid dynamics (CFD), flight-test calibration, results and benefits of differential pressure based local angle-of-attack and total pressure measurements through 20 static pressure ports and a Kiel pitot. These sensors were installed in a single-aisle, four-abreast, full fly-by-wire medium-range jet airliner with twin turbofan engines and conventional HT (low vertical position).

scholarly journals A Switching-Based Interference Control for Booster Separation of Hypersonic Vehicle

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qin Zhong ◽  
Wenbin Wu
Keyword(s):  
Control System ◽  
Flow Field ◽  
Dynamic Pressure ◽  
Variable Structure ◽  
Hypersonic Vehicle ◽  
Separation Process ◽  
Hypersonic Vehicles ◽  
High Dynamic ◽  
Static Instability ◽  
State Changes

Whether launching from the ground or in the air, hypersonic vehicles need the booster to accelerate to a predetermined window, so as to meet the requirements of scramjet engine ignition. Therefore, there is interference suppression between boosters and hypersonic vehicles under the high dynamic pressure, which has become a key technical problem that affects the success of flight tests, especially when the aircraft is statically unstable. A method of variable structure switching-based control is proposed in this paper for rapid suppression on hypersonic vehicle booster separation interference. Switching control systems in real time according to state changes caused by flow field interference, the method can keep the attitude stability of hypersonic vehicle booster separation under the high dynamic pressure of static instability. The aerodynamic calculation model of the hypersonic vehicle booster separation process is established first, which adopts an unsteady solution and clarifies the aerodynamic interference characteristics of the afterbody on the vehicle in booster separation. Then, according to the characteristics of the flow field, the dynamics of the vehicle in and out of the interference area are converted into subsystems with switching characteristics. Using the dimension reduction and variable structure method, the switching control surface of the control system is established. On the basis of the vehicle state changes caused by flow field, the control system on the orbital change surface can be switched in real time to achieve stable attitude in the process of separation interference. Meanwhile, considering the additional interference torque generated by the afterbody to the vehicle in the separation process, a control system for interference suppression of the booster separation is designed. Simulation results verify that the designed control system can rapidly suppress the booster separation interference when the dynamic pressure is about 150 kPa and the vehicle has the static instability of 5%, thereby realizing the stable attitude of the vehicle.

Robust adaptive gliding guidance for hypersonic vehicles

2017 ◽  
Vol 232 (7) ◽  
pp. 1272-1282 ◽  
Author(s):  
Jianwen Zhu ◽  
Luhua Liu ◽  
Guojian Tang ◽  
Weimin Bao
Keyword(s):  
High Performance ◽  
Minimum Energy ◽  
Angle Of Attack ◽  
Load Factor ◽  
Hypersonic Vehicles ◽  
Aerodynamic Coefficients ◽  
Unknown Parameters ◽  
Guidance Law ◽  
Optimal Guidance ◽  
Robust Adaptive

A novel robust adaptive gliding guidance strategy based on multi-constrained analytical optimal guidance and online identification of aerodynamic coefficients for hypersonic vehicles is proposed. The guidance models are constructed in both longitudinal and lateral directions and optimal guidance law, namely required load factor, is designed with minimum energy consumption to satisfy terminal position, altitude and flight-path angle constraints. Considering aerodynamic coefficients are the core factors in the angle-of-attack calculation, it constructs the aerodynamic models in the form of quadratic polynomial function and employs extended Kalman filter to estimate the unknown parameters. Using the optimal guidance law based on current flight states and terminal constraints and the identified outputs to calculate angle-of-attack, then the gliding guidance mission can be achieved adaptively and robustly. Finally, the simulation experiments of high performance of the common aerothermodynamics-shell vehicle (CAV-H) are carried out to validate the guidance performance.

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