Vertical Launching System Research Articles

Parametric study of a VLS based on 2-D FSI analysis

Vertical launching system (VLS) is useful in operating and sheltering high-speed rockets. The aft closure in the plenum plays a significant role in protecting the interiors from the exhaust gas induced by the ignition of adjacent or in-positioned canisters. During the aft opening/closing event, a complex flow is propagated into the VLS. By presence of such structural components, it is necessary to analyze the interaction between the deforming aft closure and a highly pressurized plume.This paper presents a two-dimensional fluid–structure interaction (FSI) simulation under high pressure loading condition for preliminary design of VLS. A quadrilateral 9-node element based on co-rotational (CR) framework is used to predict the geometrically/materially nonlinear deformation of the aft closure while supersonic impinging jet plume is predicted by fully Eulerian modeling. A contact mechanism is also utilized to apply reaction forces between the structures and inclined plenum using a penalty term. The interface and boundary conditions are obtained by the hybrid particle level-set method via the Ghost framework. Furthermore, a parametric study is conducted by changing the thickness of the aft closure and the inclined angle of the plenum. It is expected that the magnitudes of pressure and temperature can be decreased by the introduction of appropriate thickness of the aft closure and inclined angle in the plenum.

Numerical Simulation of Fluid–Structure Interaction Problem Associated with Vertical Launching System

We develop a combined Lagrangian–Eulerian method for transient fluid–structure interaction problems. Based on the ghost fluid framework for improving interface tracking accuracy between a fluid (hot rocket exhaust plume) and a high strain rate deforming solid (rear cover of a vertical launch system), the numerical coupling between the two media ensures an accurate description of the flexible structure. A nine-node quadrilateral element based on total Lagrangian formulation is used, while the hydrodynamic finite difference method is used for the supersonic exhaust plume that forms a complex flow within the plenum. The Lagrangian, Eulerian, and fluid–structure interaction coupling methods are verified by ANSYS results and related theories. A two-dimensional simulation of the full vertical launch system operation mode is conducted. This requires an accurate reproduction of the complex flowfield generated by the rapid rear cover opening under a high-pressure plume during rocket launch. This fluid–structure interaction problem solution may be used for future design upgrades when a vertical launch system is exposed to unusually harsh interactive gas and structure conditions.

Numerical Study on Density Gradient Carbon–Carbon Composite for Vertical Launching System

This study presents new carbon–carbon (C/C) composite that has a density gradient within single material, and estimates its heat conduction performance by a numerical method. To address the high heat conduction of a high-density C/C, which can cause adhesion separation in the steel structures of vertical launching systems, density gradient carbon–carbon (DGCC) composite is proposed due to its exhibiting low thermal conductivity as well as excellent ablative resistance. DGCC is manufactured by hybridizing two different carbonization processes into a single carbon preform. One part exhibits a low density using phenolic resin carbonization to reduce heat conduction, and the other exhibits a high density using thermal gradient-chemical vapor infiltration for excellent ablative resistance. Numerical analysis for DGCC is performed with a heat conduction problem, and internal temperature distributions are estimated by the forward finite difference method. Material properties of the transition density layer, which is inevitably formed during DGCC manufacturing, are assumed to a combination of two density layers for numerical analysis. By comparing numerical results with experimental data, we validate that DGCC exhibits a low thermal conductivity, and it can serve as highly effective ablative material for vertical launching systems.

Analysis of Geometric Characteristic of Missile Vertical Launching System Guide Rail

By analyzing the shipboard missile vertical launching system (VLS), we simplified the assembly model and reconstructed it with mathematical methods, established the clearance parameter and deviation angle mathematical formulas. In considering of the assembly errors of guide rail in missile vertical launcher system, we studied assembly clearance parameters effects on the system at first. And then established dynamic simulation model, researched the relationship between assembly clearance parameters and missile launching status. At last, used the above relationship model and conclusions, developed a prototype simulation method, and provided the foundation and guidance for design of missile vertical launching system.

함정 수직발사대 화염처리장치 형상에 따른 유동특성 연구

The gas management system for a vertical launching system must be safely managed within a ship. The plenum and uptake are capable of containing and surviving a full-burning restrained firing without loss of gas management integrity. To secure the safety, the pressure characteristics with a supersonic under-expanded jet on a gas management system are numerically investigated using computational fluid dynamics. The results of present analysis and the preliminary design of the gas management system are described in this paper.Keywords : Gas Management System(화염처리장치), Vertical Launching System(수직발사대), Supersonic Impinging Jet(초음속 충돌 제트)

수직발사 유도탄의 진동시험에서 유도탄 장착방향의 영향에 대한 연구

Vertically-launched missiles are supported as erected vertically in the vertical launching system of warship, and they should be mounted in the same way when vibration-tested. However, mounting missiles vertically makes a fixture, which is a supporting structure, bulky and heavy so requiring a high-performance exciter. Mounting missiles as laid down horizontally in a vibration test is economical regarding fixture manufacturing and exciter performance, but it makes test results incorrect because the different mounting direction has effects on the test results. A bending moment due to missiles' weight happens to missiles, and resilient mounts, which support missiles in the vertical launch system, deflect differently from the real situation because of the static deflection of these mounts due to missiles' weight. If the resilient mounts supporting missiles have nonlinear force-deflection characteristics, vibration test results become more different from the true results. This paper proposes to support missiles with an additional resilient mount such as a bunge code in order to solve those problems coming from mounting vertically-launched missiles as laid down horizontally in vibration tests. The proposed approach enables to obtain the same test results as in their actual mounting condition even though vertically-launched missiles are mounted in a different direction.

수상함에서 발사된 수직 발사 유도탄 초기 거동의 통계적 해석

A vertical launching system(VLS) is a system for holding and firing missiles on surface ships. When a missile is launched in VLS, relative motion between canister and missile and drag force induced by wind can cause initial unstability of a missile. Thus dynamic analysis of initial behavior of vertically launched missile should be performed to prevent collision with any structure of a ship. In this study, dynamic analyses of initial behavior of vertically launched missile are performed using Monte-Carlo simulation, which relys on random sampling and probabilistic distribution of variables. Each parameter related with dynamic behavior of a missile is modeled with probability variables and Recurdyn, a commercial software for multi body dynamic analysis, is used to perform Monte-Carlo simulation. As a result, initial behavior of a missile is evaluated with respect to various performance indexes in a probabilistic sense and sensitivity of the each parameters is calculated.

Supersonic Jet Impingement Navier-Stokes Computations for Vertical Launching System Design Applications

The jet impinging flow structure exhibits such complex natures as shock shell, plate shock, and Mach disk, depending on the flow parameters. The main parameters are the ratio of the jet pressure to the ambient pressure and the distance between the nozzle and the wall. Complexity and unsteadiness of this flow pose quite a numerical challenge for the flux-difference line of schemes, defying easy capture of the plate shock and recirculation zone at the jet center. Such difficulties are overcome and stable solutions are obtained first for jet impingement on a flat plate and then within a vertical launching system, yielding locations, as well as magnitudes of maximum pressure and heat flux for hardware designers. The plate shock and wall pressure beneath are found to oscillate with a frequency between 1 and 10 kHz, depending on the flow condition.

Engineering Applications of Jet Impingement Associated with Vertical Launching System Design

In the course of missile system design, jet plume impingement is encountered in designing airframe as well as launchers, requiring careful investigation of its effect on the system. In the present paper, recent works on such topic are presented to demonstrate usefulness of CFD results in helping design the hardware. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. The main parameters are the ratio of the jet pressure to the ambient pressure and the distance between the nozzle and the wall. In the current application, the nozzle contour and the pressure ratio are held fixed, but the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance. The same methodology is then applied to a complex vertical launcher system (VLS), capturing its flow structure and major design parameter. These applications involving jets are thus hoped to demonstrate the usefulness and value of CFD in designing a complex structure in the real engineering environment.

STANDARD Missile 2 BLOCK IV Missile/Ship Integration

ABSTRACTThe newest missile in the Navy's Vertical Launching System (VLS) inventory is the STANDARD Missile 2 BLOCK IV. The BLOCK IV missile employs a Thrust Vector Controlled (TVC) booster, the MK 72, which has made very high altitude, increased cross‐range, and long range engagements possible. The MK 72 exhaust mass flowrate is two to three times greater than the previous missile considered when evaluating worst‐case exhaust plume effects to topside equipment.Tests have been performed to determine the effect of the BLOCK IV integration into the fleet. The overall intention of these tests was to provide a smooth and seamless integration of the BLOCK IV missile into fleet service. By performing integration tests prior to fleet introduction, hazards directed toward personnel or equipment associated with the launch of the BLOCK IV become known and steps can be taken to rectify those hazards. This paper discusses the various evaluations of the MK 72 rocket motor exhaust plume effects to AEGIS Vertical Launching System ship's topside equipment. The tests were conducted during static developmental rocket motor firings and live‐firings from the Vertical Launching System at White Sands Missile Range.

Computer Aided Engineering and Shock Analysis for the Foundation of a Modularized Vertical Launching System

ABSTRACTThe major objective of this paper is to describe a computer aided methodology for structural integration and analysis. Using the example of recent work in the installation of modular gun and vertical launch missile systems in warships, the reader is guided through a typical case of computer aided structural design and shock analysis, how the models are defined and tested, how the models are modified in order to be compatible with computer capacity, how structural elements are selected to simplify computations, and finally how the results of these operations are used to define the final product before construction and installation.With the maturation of the computer aided process as applied to the whole ship product, more attention must be focused on improving the individual elements of computer aided design (CAD), computer aided engineering (CAE) and computer aided manufacturing (CAM) and the integration of these processes and their products through computer integrated manufacturing (CIM).The application of the CAE techniques described herein to large maritime systems such as combatant, auxiliary and support, and commercial ships and to other large structures such as semisubmersible and fixed platforms is powerful and highly in demand. There is now a means to optimize large structural systems in terms of their discrete subsystems and components and harmonize the entire design while providing the proper design integrity at each successive level of detail.

MK 41 VERTICAL LAUNCHING SYSTEM FLEET APPLICATION

ABSTRACTThe unique physical construction and launch control system architecture of the MK 41 vertical launching system (VLS) makes it particularly adaptable to a variety of missiles and ship classes. The U.S. Navy began installing the MK 41 VLS in deep draft combatants early this year.System attributes such as increased firepower, reduced manning and training requirements, high reliability and low maintainability indicate the MK 41 will best answer the fleet's requirement for highly capable launchers at minimum life cycle cost. Several launcher variants can be readily configured from MK 41 launcher components. Two lengths have been developed and proved during land based and at‐sea tests. These MK 41 derivatives retain all the benefits of the VLS while permitting a tailored defense capability throughout the surface fleet.

INTERNAL BALLISTICS OF WEAPON LA UNCHING SYSTEMS

ABSTRACTThe management of hot rocket exhaust has been of particular concern in the development of the new canister type launching systems. Special materials have been required to protect the launchers and ships from the rocket exhaust. The design of the Vertical Launching System (VLS) for STANDARD missile has been particularly critical due to the tremendous temperatures and quantity of exhaust from the missile and the additional fact that the exhaust must be safely managed within the ship.The analysis of the internal gas flows through the new missile launching systems has been a challenging problem in transient internal ballistics in which many complicating factors have played significant roles. For example, strong pressure waves traveling through the system govern the mechanical strength of the design. Turbulent convective heat transfer from the hot exhaust stream provides the largest thermal input to the launching system and requires the design of protective material for the interior surfaces of the canisters and launchers. Complicated and ill‐understood chemical reactions occur in the exhaust stream as it passes through the system, causing the chemical composition of the exhaust, and, therefore its material properties, to be different at every point.

THE LATEST IN SHIP WEAPON LA UNCHERS ‐ THE VERTICAL LAUNCHING SYSTEM

ABSTRACTThe primary features of the Vertical Launching System (VLS) planned for initial installation aboard the CG 47 Class (beginning with the CG‐52) and for retrofitting into the DD 963 Class Ships are described in detail. Although modular in construction, the magazine sizes planned replace, with 61 missile cells and an integral strikedown system, the 44 missile MK26 Mod 1 Guided Missile Launching System. The modular concept of the launcher design and the certified round concept, utilizing a sealed canister to protect the missile from weapon station to launch, are described. Design features and development of both the gas management system and the strikedown system are discussed.The engineering development tests which have successfully demonstrated the ability of the launcher to withstand the ignition pressure pulse and absorb the heat of an accidental restrained firing are included as well as those tests which demonstrated performance of the radome after “flythrough” of the exhaust plume.A major advantage of the Vertical Launching System is its ability to engage simultaneously air, surface, and underwater targets. Demonstration tests confirming this capability through vertical launches of the STANDARD, HARPOON, TOMAHAWK, and a modified ASROC missiles are discussed. Two unique test facilities built to minimize development costs are described ‐ one is used to launch and catch the missile intact, providing post test examination and re‐use, and the other duplicates the ship's deck and launcher as well as roll and pitch motion to develop the strikedown equipment and to train the crew.Finally, performance and reliability comparisons are drawn between the Vertical Launching System and current rail‐type launchers.

THE NEEDS FOR MODERN TECHNOLOGY AND THE IMPACTS ON COMBAT SYSTEM DESIGN

ABSTRACTThis paper considers a number of combat system studies relating to surface combatants, the results of which indicate certain deficiencies in existing systems and equipments within an increasingly hostile environment. This situation is used as a foundation for new technology applications. An overall systems engineering approach is presented as a means of closing the gap between performance requirements and the environment using available technology within traditional guidelines.The combat system environment is discussed under three headings. The immediate environment considers the ship platform restraints on the combat system together with the effects of the life span of the ship, subsystem autonomy, and operational data requirements. The external environment considers mission requirements, the natural elements, the threats, and man‐made interference. The third aspect of the environment is concerned with the need to maintain operational readiness during peacetime.Based upon the environmental considerations, some fundamental Top Level Requirements are derived. The application of available technology is evaluated using three major combat system elements to illustrate an approach to satisfying the postulated requirements. The examples selected include a Vertical Launching System (VLS), a Multi‐Function Phased‐Array Radar (MFAR), and a Distributed Processing System (DPS). In each case, the new technology concept is stated, examined in terms of requirements, and compared with existing systems. Potential approaches, problems and relationships with the total combat system are discussed.Vertical Launching concepts, Multi‐function Phased‐Array Radar concepts, and Distributed Processing concepts are presented. The closing summary addresses the problem of matching requirements to the environment. The systems engineering approach is reiterated as a method to achieve the optimum balance of performance, availability, and cost.