Reaction Control Jets Research Articles

Experimental and Numerical Investigation on Attitude Adjustment Characteristics of Spacecraft with Impulse Thruster

AbstractThe spacecraft serves as an effective tool for the space exploration. The present study is devoted to investigate the yaw attitude adjustment motion of the spacecraft influenced by the reaction-jet control system. A novel spacecraft device with impulse thrusters is designed for the vacuum test. And a synchronous test system, equipped with high-speed cameras, is established to record the motion process of the spacecraft under the various initial setting conditions. Subsequently, a six degrees of the freedom exterior ballistic model is calculated considering the interior ballistic process in the impulse thruster. The experimental results confirm that the position change of the designed device’s center of mass aligns with expectation, and the prediction error of final attitude angle remains below 2%. Based on this foundation, the change rule of the impulse thrust under different main charge loads is explored. The non-linear impulse thrust needs to be coupled with the rotation motion to enhance calculation accuracy. And the position of the center of mass is investigated to illustrate the advantage of the designed spacecraft structure. Finally, the calculation of the ignition interval time required for each target attitude angle is conducted, providing the essential data for further optimization design research. The outcomes from this paper can offer valuable technical means for advancing studies on the spacecraft attitude control.

Detached Eddy Simulations of a Reaction Control Jet from an Axi-Symmetric Body in a Supersonic Crossflow

The introduction of a control jet into a supersonic cross flow yields a substantial region of separated flow, manifesting in the vicinity of the injection site. This, in turn, alters the distribution of pressure on the primary body, thereby influencing the effectiveness of the injected jet’s capacity to produce the desired control forces and moments. In the context of an axi-symmetric parent body, this disruption typically leads to a reduction in effectiveness, owing to the overflow of the shock structures encompassing the parent body. The present study investigates the injection of a reaction control jet into a supersonic crossflow using different Detached Eddy Simulation (DES) techniques. The side jet is injected from an orifice on an axi-symmetric parent body, which is aligned with the crossflow direction. The effects of the side jet on the flow field are analysed in terms of general flow features and spectral behaviour of pressure and turbulent kinetic energy. The DES results are compared with those obtained from RANS using various turbulence models. The overall effect of a transient interaction pulse is characterized using URANS and two different DES models.

Parameters Influencing the Effectiveness of Reaction Control Jets on the Basic Finner

Reaction control jets provide a practical option to increase the acceleration rates of high-performance aerodynamic vehicles. Unfortunately, a designer or system engineer incorporating reaction control jets into a design cannot simply add the jet as a point force because it does not account for the change in force due to the modifications of the flowfield caused by the jet. The changes made to the flowfield can impact the forces and moments, enhancing, mitigating, or even reversing the desired force or moment, depending on a complex set of factors. This study examines the influence of different jet configurations, modifications to freestream parameters, and the presence of control surfaces on the body. It is shown that the proximity of the jet to the control surfaces has the most significant impact on the resulting force amplification. The emphasis is placed on differentiating between how the jet interacts with the body and fins. Ultimately, this shows that the interaction with the fuselage is consistent and self-similar, whereas the fins are primarily influenced by the jet blocking the flow and generating a shock that imparts high pressure on the control surface, increasing the force in the direction of the jet.

Modeling of a reaction control jet interacting with high-speed cross-flow in slip flow regime

Numerical investigation of a sonic reaction control jet interacting with the high-speed cross-flow has been carried out over a generic missile body. Simulations are performed in the early-hypersonic slip flow regime for air, CO2, and helium jet gases. An open source computational fluid dynamics tool, OpenFOAM is used to model the steady state, three-dimensional compressible Navier–Stokes equations with k-ω shear stress transport turbulence model. The conventional computational fluid dynamics solver is extended with additional features, such as transport of species, nonequilibrium boundary conditions for velocity slip and temperature jump, and a heat load calculation utility based on the sliding friction effect. The extended solver is validated with the direct simulation Monte Carlo results for the case of a sonic argon jet injected into hypersonic nitrogen cross-flow. The extended solver is able to accurately capture all the qualitative flow features like separation shock, bow shock, and barrel shock, and it also improves heat load predictions in the slip flow regime. The main objective of the present work is to study the effect of rarefaction and change in jet gas species on the complex flow topology, heat load distribution, and spread of jet gas on the missile body. Heat load predictions are found to be strongly dependent on the slip velocity of molecules in addition to the temperature gradient near the wall. The strength of a bow shock and a barrel shock is higher for helium jet, compared to air and CO2 jets, which spread more along the missile body, and weaker shocks and reduced heat load is generated. The current work is significant from the perspective of the thermal design of spacecraft surfaces and positioning of the optical sensors.

Numerical investigation of a pulsed reaction control jet in hypersonic crossflow

This paper presents a numerical study on the flow structures developed when a pulsed reaction control jet is operated in a hypersonic crossflow with a laminar boundary layer. Understanding these flow structures is important to the design of reaction control jets and scramjet fuel injectors. Implicit large-eddy simulations were performed with a round, sonic, perfect air jet issuing normal to a Mach 5 crossflow over a flat plate, at a jet-to-crossflow momentum ratio of 5.3 and a pressure ratio of 251, and with square-wave pulsing at Strouhal numbers of 1/6 to 1/3, based on jet diameter and free-stream velocity. Pulsing the jet allows the shock structure to partially collapse when the jet is off. This shock collapse affects the shedding frequency of shear-layer vortices, the formation of shear-layers downstream of the jet outlet, and the formation of longitudinal counter-rotating vortices. The lead shocks formed at jet start-up allow deeper penetration by increasing the effective jet-to-crossflow momentum ratio near the jet outlet and by preventing interaction between hairpin vortices. Normalised penetration was increased by a maximum of 68% compared with the steady jet. Pulsing also provides a higher jet interaction force per unit mass flow rate compared with a steady jet, with a 52% increase recorded at a 33% duty cycle. Temporal and spatial variations of surface pressure are important for reaction control applications and have been quantified. Pressure distribution depends strongly on duty cycle, and higher interaction force per unit mass flow rate was observed in cases with low duty cycle.

MISSILE VERTICAL LAUNCH SYSTEM WITH REACTION CONTROL JETS

The paper deals with a concept of a missile vertical launch system using reaction control jets. The purpose of the study was a detailed investigation of a method optimizing fuel consumption in the first phase of the missile flight to increase the range and optimize the flight path. In the designed system the missile is ejected vertically and turned to the desired position by using corrective engines before the sustainer motor is started. The dynamics and controllability of the missile at low velocities were studied. The physical and mathematical model of the object has been described, taking into account the nonlinearities connected with the dynamics of the rocket itself, the disturbances caused by firing the rocket engine as well as some effects the unsteady aerodynamics. A method identifying the aerodynamic characteristics of the missile and an algorithm controlling the correction engines is presented. A prepared mathematical model of the missile was used to create a simulating environment. The results of numerical simulations in the form of graphs and tables are presented.

Unsteady Fluid–Structure–Jet Interactions of Agile High-Speed Vehicles

This paper considers the nonlinear and unsteady loads environment of an agile high-speed vehicle with reaction control jets and structural degrees of freedom to account for the flexibility of the slender vehicle. At supersonic flow conditions, the jet flow interacts with the external flow and induces a complex pressure distribution on the vehicle surface. This interaction has been well documented in the literature for jets mounted on rigid structures and considering steady-state flow. However, the fluid–structure interaction must be considered for a slender vehicle due to increased flexibility. Static and dynamic aeroelastic analyses using direct and reduced-order modeling based on the aeroelastic capability of the FUN3D computational fluid dynamics code are presented. The results show that dynamic rigid-body motion, structural deformation, and pulsating jets lead to variations in the applied loads up to 50% compared to the equivalent conditions with a rigid vehicle without jet interaction. A modeling approach for the unsteady loads is compared against the dynamic aeroelastic solution. The model-predicted results capture some of the unsteady effects, and the results show good correlation with the computational fluid dynamics solution for low-frequency inputs.

Transient interaction between a reaction control jet and a hypersonic crossflow

This paper presents a numerical study that focuses on the transient interaction between a reaction control jet and a hypersonic crossflow with a laminar boundary layer. The aim is to better understand the underlying physical mechanisms affecting the resulting surface pressure and control force. Implicit large-eddy simulations were performed with a round, sonic, perfect air jet issuing normal to a Mach 5 crossflow over a flat plate with a laminar boundary layer, at a jet-to-crossflow momentum ratio of 5.3 and a pressure ratio of 251. The pressure distribution induced on the flat plate is unsteady and is influenced by vortex structures that form around the jet. A horseshoe vortex structure forms upstream and consists of six vortices: two quasi-steady vortices and two co-rotating vortex pairs that periodically coalesce. Shear-layer vortices shed periodically and cause localised high pressure regions that convect downstream with constant velocity. A longitudinal counter-rotating vortex pair is present downstream of the jet and is formed from a series of trailing vortices which rotate about a common axis. Shear-layer vortex shedding causes periodic deformation of barrel and bow shocks. This changes the location of boundary layer separation which also affects the normal force on the plate.

A hybrid guidance law of LOS acceleration feedback for missile against maneuvering targets

A quantised backstepping robust guidance law of three-dimension(3-D) space for compound control of reaction control jets and aerodynamic surfaces is proposed to attenuate the unknown target manoeuvre in this paper. The presented guidance law guarantees that the rates of line of sight converge to a residual circle centred at the origin whose radius is depended on the target manoeuvres, quantised length and guidance law gains. The simulations are given to illustrate the effectiveness of the proposed guidance law.

Robust sliding mode control with ESO for dual-control missile

This paper proposes a novel composite dual-control by combing the integral sliding mode control (ISMC) method based on the finite time convergence theory with extended state observer (ESO) for a tracking problem of a missile with tail fins and reaction-jet control system (RCS). First, the ISMC method based on finite time convergence is utilized to design the control law of tail fins and the pulse control of RCS for the dual-control system, ensuring the system with rapid response and high accuracy of tracking. Then, ESO is employed for the estimation of aerodynamic disturbances influenced by the airflow of thruster jets. With the characteristic of high accuracy estimation of ESO, the chattering free tracking performance of the attack angle command and the robustness of the control law are achieved. Meanwhile, the stability of the dual-control system is analyzed based on finite time convergence stability theorem and Lyapunov's theorem. Finally, numerical simulations demonstrate the effectiveness of the proposed design.

Aerothermal exploration of reaction control jet in supersonic crossflow at high altitude

Multiple reaction control jets injected normal to free-stream is used to manoeuvre aerospace vehicle at high altitudes. Detailed aerothermal analysis of a high speed aerospace vehicle with multiple lateral jets is carried out in its full trajectory covering wide range of Mach numbers and altitudes. Three dimensional RANS simulations with laminar-turbulent transition models are performed at several instances in the flight trajectory using commercial CFD solver. Numerical simulations captured all complex flow phenomena of free stream & multi-jet interaction at high altitudes and its influence on vehicle airframe temperature. Heat flux data base obtained from CFD analysis is used for transient thermal analysis of flight vehicle. High temperature local hot spots in jet wake regions and detailed thermal analysis of total vehicle provided important inputs to the system design.

Fluorescence Imaging of Reaction Control Jets and Backshell Aeroheating of Orion Capsule

Planar laser-induced fluorescence of nitric oxide was used to visualize the interaction of reaction control system jet flows on the afterbody of a hypersonic capsule reentry vehicle at the Calspan-University at Buffalo Research Center’s Large Energy National Shock Tunnel I reflected shock tunnel facility. The interaction of pitch and roll jets with the flowfield was investigated. Additionally, thin-film sensors were used to monitor heat transfer on the surface of the model to detect localized heating resulting from the firing of the reaction control system jets. Visualizations of the capsule shear layer using both planar laser-induced fluorescence and schlieren imaging compared favorably. The structure of the roll jet was found to be significantly altered due to interactions with the flowfield. Additionally, the presence of the roll jet appeared to change the nature of the shear layer from steady laminar to unsteady. The pitch jet structure was only disturbed in the far field. Comparison of the planar laser-induced fluorescence jet-fluid visualizations and the surface heat flux distributions indicate that the regions of enhanced aeroheating are not caused by the jet fluid itself impinging on the surface, but rather by the presence of jet-induced horseshoe vortices and shock wave/boundary-layer interactions.

Capture condition for endo-atmospheric interceptors steered by ALCS and ARCS

This contribution deals with capture condition for interceptor missiles steered by aero-lift control system (ALCS) and attitude reaction-jet control system (ARCS). With the guidance law derived from bounded differential game formulation, existence condition of capture zone is studied for the case that the interceptor has advantage on maneuverability and disadvantage on agility. For the existence of the open capture zone, ARCS can only close after the engagement terminates. Moreover, ARCS also needs to contribute to maneuverability over the minimum required value. More fuel will be required if ARCS increases its contribution to maneuverability. The minimum required fuel occurs at the tangent point of two curves: the curve of critical parameters and a candidate constraint curve, which is also true even for the complex propellant constrain. The validity of these results is also demonstrated by simulations.

Agile Turn Control for Air-to-Air Missile Based on Reaction Jet Control System

This paper focuses on agile turn control for air-to-air missile flying in the horizontal plane. The attitude dynamics is discussed and variable structure control (VSC) method for attitude control is analyzed. After analysis of the dynamic function about velocity angle, a staged control method using VSC based on reaction jet control system (RCS) is proposed to achieve fast change of velocity direction and attitude in a short time. The simplex method is used for trajectory optimization. The simulation results show the feasibility of the staged control method which makes the missile turn faster than the situation of attitude control method. The new method demonstrates that RCS is able to control the missile to realize 180°change both for the velocity angle and attitude angle.

Precision Attitude Stabilization: Incorporating Rise and Fall Times in Gas-Based Thrusters

T HRUSTERS have been a popular choice for microsatellite attitude control systems owing to their high power-to-weight ratio and because they use a lesser number of moving parts that can fail over time. Thruster applications to spacecraft attitude stabilization have been widely studied in the past. The reader is pointed to classical texts like Sidi [1] and Bryson [2] and the references therein for an extensive treatment of the topic. Thrusters have typically been used as on–off actuators and, therefore, are not suitable for high pointing accuracy requirements (e.g., space interferometry missions like the Terrestrial Planet Finder [3,4] and MicroArcsecond X-Ray Imaging missions [5]). There have been numerous developments in the design of variableamplitude thrustingwithout excessive loss of efficiency of operation. Fisch et al. [6] studied the variable operation of a Hall thruster without reduction in operational efficiency at low mass flow rates using segmented electrodes. Stone [7] developed a prototype variable-amplitude cold-gas thruster using a high-speed intelligent loading system that offered significant improvement in performance characteristics over traditional reaction control jets. He also stated the possibility of rescaling the system to achieve desired thrust output without significant penalties on performance. Further classical results pertaining to pulse-width pulse-frequency modulation [1] also provided efficient means of generating variable torques using on–off thrusters. These advances enabled the application of continuous feedback design for spacecraft attitude stabilization using thrusters. The feasibility of conventional thrusters to microsatellite and nanosatellite applications is, however, still limited by several factors. Microsatellite maneuvers need thrusts that are below the minimum threshold from conventional thrusters. Recent developments in micropropulsion therefore seek to reduce the lower thrust threshold and the minimum pulsewidths over which thrusters can be operated. For an extensive survey of modern micropropulsion technologies, the reader is referred to Rossi [8], Mueller [9], Stanton [10], and the references therein. Additionally, gas-based thrusters have nonzero rise and fall times that are needed to establish steady-state propellant flow (cold-gas systems) and for propellant reaction (hot-gas systems) [11]. These times vary between a fewmilliseconds to several hundred milliseconds. It is important to ensure that attitude control torque commands be implemented during the maximum thrust phase, since the thrust provided during the rise and fall phases is uncertain. Here, we consider the attitude stabilization problem of a microsatellite employing a variable-amplitude cold-gas thruster so as to ensure zero torque commands during thruster rise and fall times. To this end, an artificial control prescaling g t is defined, typically chosen to be a periodically modulated step function representing the thruster on and off schedules. The actual applied control torque to the system is g t u t , while the designed control signal is u t . Designing a continuous control law with a g t of possibly zero over severalwindows of time is a nontrivial task due to nonapplicability of standard feedback linearization results. Loria et al. [12] have cited several classes of open problems where the control is scaled by a periodically singular gain g t . One specific problem concerns stabilization of _ x f x g t; x u using a stabilizing control u for dynamics _ x f x u. To this end, Jiang et al. [13] have shown that, in general, a feedback u k x that asymptotically stabilizes _ x f x p x u may not stabilize _ x f x g t p x u with g being persistently exciting (PE). The persistence filter formulation by the authors [14] for linear single-input systems is extended to design a time-varying feedback law u t for this attitude stabilization problem. It needs to be emphasized that the persistence filter construction for the attitude stabilization problem is a significant advancement over our earlier work [14] in the sense that the filter state defined here has both state and time dependence. It is shown that this controller guarantees exponential convergence of the angular velocity and the vector part of the attitude quaternion to zero. Simulations carried out on a typical microsatellite example confirm that attitude and angular velocity errors converge to the origin for the closed-loop system. Furthermore, superimposition of the on–off window g t ensures zero commanded torques over the thruster rise and fall phases, as desired. We also compared, through simulations, the performance of the controller designed here to the one obtained from the classical proportional-derivative (PD) controller [15]. This, to the best of our knowledge, will be the first attempt at employing continuous feedback control design to compensate for nontrivial thruster rise and fall times and intermittent torque actuation. Throughout this Note, we adopt the following classical definition for the persistence of excitation and exponential stability. Definition 1 ([16], p. 72): The signal g : R ! R is said to be PE if there exist finite positive constants 1, 2, and T; such that

Bounded Differential Game Guidance Law for Interceptor Missiles with Aero Fins and Reaction Jets

A differential game guidance law for an endoatmospheric interceptor missile steered by aero fins and reaction jets is developed in this paper with bounded controls. For a low-altitude endoatmospheric interceptor, the propellant of the reaction-jet control system (RCS) is restricted by the missile configuration. Considering propellant limits, the effect of the RCS thrust on homing performance is investigated through game space structures. Also, to use the RCS at an appropriate timing, game space decomposition is used to determine the initiating time of the RCS. Finally, the effectiveness of the guidance law is demonstrated by a realistic ballistic missile defense scenario. It is shown that the proposed guidance law provides a significant improvement in homing accuracy compared to the conditional one. Furthermore, under propellant limits, a bigger RCS thrust cannot guarantee a higher homing accuracy.

Modelling and simulation of an aerial vehicle steering to hit on top of the target at terminal trajectory

In this paper, combined attitude control of the terminal trajectory for an aerial vehicle is presented. The combined attitude controller includes the fuzzy adaptive aerodynamic force mode control and the direct lateral thrust mode control. The dynamic and kinematics mathematical models of the aerial vehicle are built based on the designed reaction-jet control scheme. Simulation results show that the combined control system can satisfy the requirements of the aerial vehicle overload better than the traditional mode does.

BTT autopilot design for agile missiles with aerodynamic uncertainty

The approach to the synthesis of autopilot with aerodynamic uncertainty is investigated in order to achieve large maneuverability of agile missiles. The dynamics of the agile missile with reaction-jet control system(RCS) are presented. Subsequently,the cascade control scheme based on the bank-to-turn(BTT)steering technique is described. To address the aerodynamic uncertainties encountered by the control system, the active disturbance rejection control(ADRC) method is introduced in the autopilot design. Furthermore, a compound controller, using extended state observer(ESO) to online estimate system uncertainties and calculate derivative of command signals, is designed based on dynamic surface control(DSC). Nonlinear simulation results show the feasibility of the proposed approach and validate the robustness of the controller with severe unmodeled dynamics.

Quantized Control Allocation of Reaction Control Jets and Aerodynamic Control Surfaces

Amixed-integer linear programming approach tomixing continuous andpulsed control effectors is proposed. The method is aimed at applications involving reentry vehicles that are transitioning from exoatmospheric flight to endoatmospheric flight. In this flight phase, aerodynamic surfaces are weak and easily saturated, and vehicles typically rely on pulsed reaction control jets for attitude control. Control laws for these jets have historically been designed using single-axis phase-plane analysis, which has proven to be sufficient formany applications wheremultiaxis coupling is insignificant and when failures have not been encountered. Here, we propose using a mixed-integer linear programming technique to blend continuous control effectors and pulsed jets to generate moments commanded by linear or nonlinear control laws. When coupled with fault detection and isolation logic, the control effectors can be reconfigured to minimize the impact of control effector failures or damage. When the continuous effectors can provide the desired moments, standard linear programming methods can be used to mix the effectors; however, when the pulsed effectors must be used to augment the aerodynamic surfaces, mixed-integer linear programming techniques are used to determine the optimal combination of jets to fire. The reaction jet control allocator acts as a nonuniformquantizer that applies amoment vector to the vehicle, which approximates the desired moment generated by a continuous control law. Lyapunov theory is applied to develop amethod for determining the region of attraction associated with a quantized vehicle attitude control system.

Numerical Investigation of Jet Interaction in aSupersonic Freestream

The objective of this investigation is to numerically evaluate effects of a reaction control (divert) jet on the aerodynamic performance of a generic interceptor missile operating at supersonic flight conditions. These effects include transient operation, external chemical reactions, burning, and geometric scale (full scale versus subscale). Three-dimensional computations of the highly turbulent flow field produced by a pulsed, supersonic, lateral-jet control thruster interacting with the supersonic freestream and missile boundary layer of a generic interceptor missile are evaluated. A generic missile interceptor configuration consisting of a long, slender body containing fixed dorsal and tail fins is simulated in this study. Parametric computational fluid dynamic solutions are obtained at altitude conditions corresponding to 19.7 km for the following scenarios: 1) steady-state conditions with the lateral control jet turned off; 2) steady-state conditions with the lateral control jet turned on; 3) steady-state conditions with the lateral control jet turned off with 1/10 subscale; 4) steadystate conditions with the lateral control jet turned on with 1/10 subscale; 5) transient jet startup conditions; 6) transient jet shutdown conditions; 7) steady-state, finite-rate chemistry; and 8) steady-state, frozen calculations with the chemical reactions “turned off.” A thermally and calorically perfect gas with a specific heat ratio equal to 1.4 was assumed for both the transient and geometric scale calculations. Vehicle forces and moments are assessed from each solution by integrating the surface pressures and viscous shear stresses computed on the missile surfaces. These results are used to determine the influence of the jet interaction effects on the transient, external burning, and geometric scale aerodynamic performance of the missile. The analysis predicts strong transient influences, small external burning influences, and very small full-scale vs 1/10-subscale effects for the integrated normal force and pitching moment.