Launcher Structure Research Articles

Effects of Protuberances on Surface Loads on the Vega-C Launch Vehicle

The need to meet the demands of the aerospace market in terms of payload capability, mission flexibility, and cost reduction has led the European Space Agency to develop Vega-C as an evolution of the original Vega launcher. The design of a modern launch vehicle like the Vega-C requires accurate evaluation of the thermal and mechanical loads on its surface under conditions as close as possible to real flight conditions. Despite its apparently simple aeroshape, the Vega-C surface is characterized by the presence of antennas, wiring ducts, flanges, and retrorockets. These protuberances interact with the external supersonic stream during the launcher’s flight, giving rise to locally complex flows that can impose stresses on the launcher structure through the generation of severe mechanical and thermal loads. The present work focuses on an in-depth aerothermal analysis of Vega-C protuberances under specific flight conditions. Numerical computations are carried out using the commercial solver CFD++ on multiblock structured Chimera grids to assess which protuberances are subject to the most severe surface loads. Particular emphasis is placed on the role of boundary-layer thickness in the heat flux and pressure peaks that occur on the protuberances.

Study of Dynamic Inductance Gradient of Augmented Electromagnetic Rail Launcher Considering High-Speed Motion of Armature

The rail inductance gradient is an important parameter of the electromagnetic launcher. The calculation of its value is important for the design of the launcher structure and for predicting the motion behavior of the armature. The current research on the inductance gradient analysis method of the electromagnetic rail launcher mostly does not take into account the effects of launcher size and current diffusion. This method cannot describe its dynamic characteristics, and it results in a large error compared with the actual launch. Therefore, the paper first establishes an electromagnetic rail launcher armature motion model to obtain the rail velocity skin depth under a U-shaped armature. Second, an analytical method for calculating the inductance gradient based on the dynamic skin depth of the rail is obtained, which takes into account the launcher size and velocity skin effect. Finally, the experimental results verify the correctness and accuracy of the method to achieve an accurate prediction of armature speed.

3D Analysis on Distribution of Pulsed Current in Electromagnetic Launcher Considering Contact State and Movement

In electromagnetic launcher, the pulsed current is concentrated by contact state, current skin effect (CSE) and velocity skin effect (VSE), and heat the material locally. It will lead to melt or degradation, reducing stability and service life of the launcher. In order to study the current distribution with all these various influences, a 3D transient current analysis model with dynamic conductivity assignment and contact layer is proposed in this paper. It is found that the short contact length in armature moving direction can make two peaks overlap caused by CSE and VSE, and VSE can disturb the current distribution in horizontal direction. When designing armatures, it is recommended that the contact length in the moving direction should be long enough during the entire launch process, so to isolate the two peaks, and that the central length of the armature tail should be longer than the lateral length, so to prevent the current from concentrating more at the lateral edge. These conclusions help the optimization of the launcher structure to reduce local damage caused by current concentration and extend service life. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Analisis Distribusi Debit Aliran pada Pelimpah dengan Variasi Model Bangunan Peluncur

Spillway is a structure in a dam designed to drain excess water into a downstream river. The purpose of this study was to determine the water level in the stepped and ladderless chutes and to determine the type of flow that occurs in the stepped and non-stepped chutes. The research method is a laboratory experiment and the data obtained is based on the results of observations made at the Hydraulics Laboratory of the University of Muhammadiyah Makassar. After passing through the launcher building, the water level in the 1st aperture ladder launcher is 2.7 cm, 2.9 cm in the 2nd opening, 2.9 cm in the 3rd opening. The water level in the ladderless launcher at the 1st opening is 3 cm, at the second opening is 3.5 cm, at the 3rd opening is 3.9 cm so that it can be concluded that the shape of the launcher structure influences the water level, thus the water level at ladderless launcher is larger than ladderless launcher. After passing through the launcher building, the Reynolds number on the stepped launcher with the 1st opening is 8301, on the 2nd opening is 8811, on the 3rd opening is 9061. to 3 of 26,103.

Computational simulation study on disturbance of six-rotor UAVs due to ammunition launch

According to the multi-body dynamics theory, we analyzed and derived the influence laws of the ammunition launch angle, launch timing, mounting position, and mass on the stability of unmanned aerial vehicles (UAVs) by establishing a flight dynamics model of a six-rotor UAV in the process of ammunition launch. The analyses indicated that the ammunition launch angle, the longitudinal mounting position, and the multi-round ammunition launch timing significantly affect the disturbance of the UAV. When single-round ammunition is launched, selecting the appropriate ammunition mounting position can reduce the disturbance amplitude of the position of the UAV, and when multi-round ammunition is launched, the launch timing significantly affects the overall stability of the UAV. On the basis of the overall system and ammunition-related parameters, the optimal launch timing for different deployment methods can be derived. Through modeling analysis, we can qualitatively study the stability of the system during ammunition launch, providing a reference for the design of the ammunition launcher structure and the strike timing.

Research on Transient Contact Characteristics of the Hyperbolic Rail Augmented Quadrupole Launcher

The contact surface between the armature and rails of a railgun system is unique for its high-speed sliding and current conduction, which greatly affects the performance of the launcher. In order to study the armature–rail contact characteristics of the electromagnetic railgun, this article simulates the initial contact characteristics, the conducting contact characteristics, the electromagnetic characteristics, and the temperature closely coupled to the contact characteristics based on a hyperbolic rail augmented launcher model. The influencing factors of the contact characteristics are analyzed and compared with the nonaugmented railgun with the same structural configuration, and the evaluation indices of the contact characteristics are established. The research results show that the contact characteristics of the railgun are affected by the electromagnetic force, which changes rapidly with time, which in turn affects the electromagnetic and temperature characteristics of the railgun. This launcher structure can maintain good contact conditions during launching. This study is a preliminary exploration of the contact characteristics of the hyperbolic rail augmented quadrupole launcher, making an improvement to its structural design.

Mechanical sizing of a composite launcher structure by hybridizing a genetic algorithm with a local search method

The concern of this paper is the hybridization of a genetic algorithm with a local search method to optimize a sandwich composite inter stage skirt located in the upper part of a launcher structure that involves simultaneously discrete (plies orientations and thicknesses), categorical (plies and core materials) and continuous (core thickness) design variables under several mechanical and manufacturing constraints. Genetic algorithms and local searches are two complement solutions where the essential element of local searches lies in focusing the search not on the full space of solutions but on a smaller subspace defined by the solutions that are locally optimal for the given genetic algorithm optimization engine. A significant attention is paid to the implementation of the genetic and the hybrid genetic algorithms with their different mechanisms in line with this framework. Obtained results reveal that the adopted hybrid approach is highly capable of improving the performance of the solution and saving computation time. The latter is a significant achievement especially that currently there exists an important need for lighter and more resistant structures with reduced manufacturing costs.

Numerical and experimental investigations of buffet on a diamond airfoil designed for space launcher applications

PurposeThe development of reusable space launchers requires a comprehensive knowledge of transonic flow effects on the launcher structure, such as buffet. Indeed, the mechanical integrity of the launcher can be compromised by shock wave/boundary layer interactions, that induce lateral forces responsible for plunging and pitching moments.Design/methodology/approachThis paper aims to report numerical and experimental investigations on the aerodynamic and aeroelastic behavior of a diamond airfoil, designed for microsatellite-dedicated launchers, with a particular interest for the fluid/structure interaction during buffeting. Experimental investigations based on Schlieren visualizations are conducted in a transonic wind tunnel and are then compared with numerical predictions based on unsteady Reynolds averaged Navier–Stokes and large eddy simulation (LES) approaches. The effect of buffeting on the structure is finally studied by solving the equation of the dynamics.FindingsBuffeting is both experimentally and numerically revealed. Experiments highlight 3D oscillations of the shock wave in the manner of a wind-flapping flag. LES computations identify a lambda-shaped shock wave foot width oscillations, which noticeably impact aerodynamic loads. At last, the experiments highlight the chaotic behavior of the shock wave as it shifts from an oscillatory periodic to an erratic 3D flapping state. Fluid structure computations show that the aerodynamic response of the airfoil tends to damp the structural vibrations and to mitigate the effect of buffeting.Originality/valueWhile buffeting has been extensively studied for classical supercritical profiles, this study focuses on diamond airfoils. Moreover, a fluid structure computation has been conducted to point out the effect of buffeting.

Satellite Launcher Navigation with One Versus Three IMUs: Sensor Positioning and Data Fusion Model Analysis.

Using multiple IMUs allows both their distribution along vehicle structures and a reliance on integration methods, which is not possible with a single IMU. This paper addresses the issue of relying on three IMUs instead of only one of a higher quality in the context of a satellite launcher. The impact of the IMU positions was tested by comparing collocated IMUs against IMUs installed in the head of each launcher stage. For multi-IMU configurations, three integration methods were tested: all IMUs fused in a single INS, multiple INSs fused in a stacked filter, and multiple INSs fused in a stacked filter with geometrical constraints. All navigation solutions were aided by a three-axis attitude reference sensor and were tested with and without a GPS receiver. The results show that distributing IMUs along the launcher structure does not improve navigation performances compared to having them collocated. The fusion of multiple IMUs in one INS provides equivalent results as one IMU. However, fusing multiple INSs greatly reduces estimation errors. Performances are further improved with the addition of geometrical constraints. During long GPS outages, relative velocity and position constraints should not be exploited, as they may lead to filter divergence.

New strategy to preliminary design space launch vehicle based on a dedicated MDO platform

This paper presents the methodology and the optimization strategy applied by Bertin Technologies for over 10 years to perform space launch vehicle design and implemented by using the property software platform HADES V15.0. The problem formulation consists of finding the best launch vehicle concept i.e. the one minimizing launch cost while satisfying technical, mission and architecture constraints (payload mass on final orbit, number of stages, propulsive technologies …). The strategy is based on a Multidisciplinary Design Feasible (MDF) approach coupled with the use of Genetic Algorithms (GA) for global optimization, and Gradient-Based Algorithms for final tuning and results refining. The HADES V15.0 platform provides the associated software environment, integrating a number of technical and economic modules consistently interconnected within a system optimization loop. The main disciplines taken into account in the platform are related to the launcher's propulsion, structure, aerodynamics, trajectory optimization and costs. The use of an integrated platform for multi-objective and multi-disciplinary optimization enables an efficient process and quick optimization. This methodology is particularly well fitted to the design of a small space launch vehicle, allowing to take into account the multidisciplinary nature of such a complex system and to manage the inherent sensitivity for this kind of vehicle. This platform was used specifically to design Bertin Technologies' cost-effective expandable Space Launch Vehicle (SLV) for Microsatellites, ROXANE, and to design the space launch vehicle in the H2020 ALTAIR project.

Investigation of armature-rail interaction in linear electromagnetic launcher

The behavior of the electromagnetic (EM) launcher depends on the structure of the construction. The dynamics of the EM construction and the local effects of the EM forces are topical issue in exploring and designing EM launcher device. This paper is aimed to refine mechanical behavior of the open barrel design EM launcher structure due to EM force evaluated by EM analysis based on three different shapes of armatures. The 3D finite element EM model was generated and the J×B force density distribution in the rail volume was calculated. The results of EM model calculations were applied further as input for structural mechanics model. The results of the finite element EM and mechanical analysis of the armatures influence are presented.

Electromagnetic Launching Systems to Geosynchronously Equatorial Orbit in Space and Cost Calculations

Electromagnetic launching mass driver system (projectile) has been examined and evaluated as an eligible alternative to the chemical propulsion systems, in space transportation. The projectile has been arranged to reach to its orbital speed at delivered altitude, with an energy transferred externally to a projectile all the flyway through the electromagnetic launcher. The multistage electromagnetic launcher structure contains the capacitors for storing energy and transfers this energy through a switching inductor to a mass driver. The mass driver is synchronously being energized by a voltage through an oscillating coil-capacitor circuit. This paper presents dependence and optimization of design and performance parameters of coilgun equations. Cost estimations of electromagnetic launching system are also calculated in energy per unit mass.

Optimal design of a Thermodynamic Vent System for cryogenic propellant storage

Future operations in space exploration require to store cryogenic liquids for long duration. Residual heat loads, due to heat conduction in the launcher structure or solar radiation, induce cryogenic propellant vaporization and tank self-pressurization. The Thermodynamic Vent System (TVS) permits to control self-pressurization using the following procedure: a fraction of liquid propellant is removed from the tank by a pump, cooled down by a heat exchanger and re-injected inside the tank as a jet or a spray. As no natural heat sink is available in space, the cold source is created by removing another fraction of liquid propellant which is expanded in a Joule-Thomson valve and vented to space. The sub-cooled injection is followed by vapor condensation and liquid bath destratification due to mixing. In this work, an optimization method is applied to an extended homogeneous thermodynamic model to design a TVS system maximizing the storage duration under various heat load and tank size assumptions.

Launch Vehicle Base Flow Analysis Using Improved Delayed Detached-Eddy Simulation

During the ascent of carrier rockets, the massively separated flow in the base region generates highly unsteady wall pressure fluctuations. The resulting dynamic loads can induce a response of the launcher structure called buffeting. To study the characteristics of the base flow behind three different configurations of the Ariane 5 launcher, improved delayed detached-eddy simulation in combination with unstructured grids is used. The objective of this work is to demonstrate the ability of improved delayed detached-eddy simulation to describe the impact of the connecting struts between central stage and boosters and to analyze the efficiency of a buffeting reduction device in the base region. Comparisons of the numerical results with time-resolved and time-averaged surface pressure data and particle-image-velocimetry measurements obtained from the German–Dutch High Speed Wind Tunnel are carried out in good agreement.

The mechanical structure of the WEST Ion Cyclotron Resonant Heating launchers

The WEST ICRH system has to deal with two challenging issues that no other ICRH system before ITER has faced simultaneously so far, i.e. ELMs resilience and Continuous Wave (CW) RF operation. The technical solution chosen to meet the requests imposed by the WEST scenarios is to build three new launchers based on the RF structure successfully tested in short pulses in 2007 on Tore Supra prototype launcher. This paper gives an overview of the mechanical structure of the CW ELMs resilient WEST ICRH launchers. The technical solutions chosen to drive the mechanical design are presented, in regard of the past experience on the 2007 TS prototype, together with the significant work carried out on the mechanical design to improve the launcher structure. The thermal and electro-mechanical analyses conducted and their impact on the launcher design are also presented. These three new CW ELMs resilient ICRH launchers are foreseen to be installed on WEST in 2016, and operational for the first plasmas.

Design validation of the ITER EC upper launcher according to codes and standards

The ITER electron cyclotron (EC) upper launcher has passed the CDR (conceptual design review) in 2005 and the PDR (preliminary design review) in 2009 and is in its final design phase now. The final design will be elaborated by the European consortium ECHUL-CA with contributions from several research institutes in Germany, Italy, the Netherlands and Switzerland. Within this consortium KIT is responsible for the design of the structural components (the upper port plug, UPP) and also the design integration of the launcher.As the selection of applicable codes and standards was under discussion for the past decade, the conceptual and the preliminary design of the launcher structure were not elaborated in straight accordance with a particular code but with a variety of well-acknowledged engineering practices. For the final design it is compulsory to validate the design with respect to a typical engineering code in order to be compliant with the ITER quality and nuclear requirements and to get acceptance from the French regulator.This paper presents typical design validation of the closure plate, which is the vacuum and Tritium barrier and thus a safety relevant component of the upper port plug (UPP), performed with the ASME boiler and pressure vessel code. Rationales for choosing this code are given as well as a comparison between different design methods, like the “design by rule” and the “design by analysis” approach. Also the selections of proper load specifications and the identification of potential failure modes are covered. In addition to that stress categorizations, analyses results, and prove of the soundness of the design are presented.

Theory and Circuit Model of Brush Commutation in Helical Coil Electromagnetic Launchers

A model is developed to investigate the commutation process of a helical coil electromagnetic launcher (HCEML) structure. When the armature moves, the motion of the projectile coils' magnetic energy would supply reactive power to move the leakage into and out of the coil windings of the launcher to accomplish the commutation. The energy conversion of the coil electromagnetic launcher can be considered as the process of energy transfer from the back commutation coils to the excited coils and then from the excited turns to the front commutation coils. In this paper, governing equations of the commutation were deduced theoretically, and finite-element model of HCEML was established in ANSOFT MAXWELL. Then a deeper circuit investigation into the overall performance of commutation was carried out by means of PSPICE software. The validity of the theoretical analysis and that of the circuit network model were finally verified by experiments. The results show that during the commutation process, the current of back commutation coils drops to zero with no energy remaining in the internal; the current of front commutation coils and drive-projectile coil system gradually changes to a stable value, which is related to the geometric parameters of the launcher; the drive-projectile coil system releases energy overall that is mainly used to increase the kinetic energy of the projectile; the power supply system has little effect on energy conversion and transformation at the commutating moment and just keeps the voltage and current from decaying due to the impedance and inductance of the launcher system.

Study of cavity type antenna structure of large-area 915 MHz ultra-high frequency wave plasma device based on three-dimensional finite difference time-domain analysis

A large-area planar plasma source with a resonant cavity type launcher driven by a 915 MHz ultra-high frequency wave was developed. Theoretical analysis with the three-dimensional finite difference time-domain simulation was carried out to determine the optimized launcher structure by analyzing the resonant transverse magnetic mode in the resonant cavity. Numerical result expects that the resonant electric field distribution inside the cavity dominantly consists of the TM410 mode. The resonant cavity type launcher having 8 holes in an octagonal geometry was designed to fit the resonant transverse magnetic mode. Adjusting 8 hole positions of the launcher to the field pattern of the resonant TM410 mode, we found that the plasma density increased about 40%∼50% from 1.0∼1.1 × 1011 cm−3 to ∼1.5 × 1011 cm−3 at the same incident power of 2.5 kW, compared with the previous results with the launcher having 6 holes in the hexagonal geometry. It is also noted that the electron density changes almost linearly with the incident wave power without any mode jumps.

The ITER EC H&CD Upper Launcher: Analysis of vertical Remote Handling applied to the BSM maintenance

This paper deals with Remote Handling activities foreseen on the Blanket Shield Module, the plasma facing component of the ITER Electron Cyclotron Heating and Current Drive Upper Launcher. The maintenance configuration considered here is the Vertical Remote Handling, meaning gravity acting along the launcher radial axis. The plant, where the maintenance under consideration is occurring, is the Hot Cell Facility Work Cell.The study here reported has been carried out within the presently ongoing EFDA Goal Oriented Training program on Remote Handling (GOT-RH), which aims to support ITER activities. This document and its contents have to be considered as part of a more vast RAMI analysis to be developed within the GOT-RH, which aims to maximize the Electron Cyclotron Heating and Current Drive system availability.The Baseline CAD model of the Electron Cyclotron Heating and Current Drive Upper Launcher is currently in its preliminary design phase and does not provide enough details for developing a fully detailed maintenance strategy. Therefore, through a System Engineering approach, a set of assumptions was conceived on the launcher structure, as a basis for development of a Remote Handling strategy. Moreover, to compare different design solutions related to the possibility of integrating a quasi-optical component into the Blanket Shield Module, a Trade-Off was made, and its contents are shown here.The outcome of this System Engineering approach has been formalized into Task Definition Forms whose contents are reported here. The Remote Handling strategy presented in this work will be tested in the near future both through Virtual Reality simulations and through prototype experiments.

Use of AlGaN in the notch region of GaN Gunn diodes

The wurtzite gallium nitride (GaN) Gunn diodes with aluminum gallium nitride (AlGaN) as launcher in the notch region are investigated by negative-differential-mobility model based simulation. Under the operation of self-excitation oscillation with dipole domain mode, the simulations show that the diode with two-step-graded AlGaN launcher structure can yield the maximal rf power of 1.95 W and dc/rf conversion efficiency of 1.72% at the fundamental oscillation frequency of around 215 GHz. This kind of Gunn diode structure without the low doping process is convenient for accurately controlling the dopant concentration of GaN epitaxial growth.