Launch Vehicles & Strategic Missiles

CFDRC develops multi-physics software technologies and delivers expert engineering design services for a variety of launch vehicles and strategic missiles. Over the years we have conducted detailed design studies, performed trade-off analyses, and applied high fidelity modeling & simulation on vehicles such as the Space Shuttle Solid Rocket Motors, Pegasus, Standard Missile-3, Aegis, Ground-based Midcourse Defense Interceptor, and NASA Ares.

Multi-Vehicle Stage Separation

Launch Vehicle Stage Separation is a complex, multi-disciplinary problem. Physics-based modeling and simulation tools and expertise enable better understanding of the complex systems and reduce the risks of development and operation. CFDRC has experience conducting stage separation simulations utilizing coupled CFD and six degree of freedom methodology to model the separation event and calculate the trajectory of the vehicle(s) upon stage separation. Some of our recent experiences include:

Multi-Vehicle Stage Separation
  • Predictions of NASAs Ares I-X flight vehicle aerodynamics for various trajectory points
  • Predictions of Ares I-X first stage aerodynamic characteristics including aeroshell and frustum separation and upper stage wake effects
  • Stage separation coupled CFD/6-DOF simulations of the staging event of NASA's X-43 A hypersonic research vehicle
  • Coupled CFD/6-DOF simulation of a missile staging events to predict aerodynamic and heating loads and to assess booster reverse thrust motor plume effects

Debris Transport & Fragment Analysis

CFDRC provides modeling & simulation support to develop, apply, and validate CFD tools to quantify and mitigate the risks imposed on launch vehicles and surroundings due to impacts from debris including insulation, bolts, ice, and fragments resulting from an explosive event.

Debris Transport & Fragment Analysis
  • Provided support to NASA post Columbia accident in the quantification and ssessment of debris on the space shuttle using CFD tools and technologies
  • Performed V&V and uncertainty quantification of NASA Lift Off Debris Transport analysis process
  • Developing and applying database driven 6DOF tools to predict aerodynamic coefficients and trajectories for debris fragments following a missile intercept

Trans-atmospheric Flight

Hypersonic flight vehicles excite the air surrounding them to very high temperatures in the post-shock and boundary layer regions. Various chemical reactions associated with the elevated temperatures are initiated. These reactions affect the thermodynamic and transport properties of the air, as well as aerodynamic and thermal loads experienced by trans-atmospheric vehicles. CFDRC has developed and applied high-fidelity computational tools for accurate prediction of aerothermal environments around supersonic spacecrafts. CFDRC’s Unified Flow Solver (UFS) facilitates simulations of rarefied, transitional and continuum flows by adding advanced non-equilibrium chemistry coupled to radiation transport and plasma capabilities. Some of the projects that support development of and use UFS technologies include:

Trans-atmospheric Flight
  • Post missile intercept fragments aerodynamic coefficients predictions at all flight regimes
  • Predictions of high speed reacting flows for a wide range of applications including entry/re-entry, descent, and landing profile across multiple flight regimes
  • Lunar lander plume impingement and interaction with lunar soil

Liquid Propellant Sloshing & Damping

Propellant sloshing is a potential source of disturbance critical to the stability of launch vehicles. Sloshing is a wave phenomenon, and is driven by gravitational force, surface tension and surface kinematics. Sources of sloshing force comes from the lateral disturbance, oscillatory thrust force, or angular rotation of the vehicle during the powered phase of the flight, particularly during takeoff, engine shut off, and flight maneuvers. CFDRC has experience performing modeling and simulation of cryogenic propellants in the launch and ascent environment. The multi-physics flow solver CFD-ACE+, originally developed by CFDRC, includes a volume of fluid (VOF) module designed for applications involving two immiscible fluids. CFD-ACE+ has been validated and proven to be highly effective at modeling the fluid-structure interaction associated with propellant sloshing and aiding in the design of dampers to mitigate this risk.

Liquid Propellant Sloshing & Damping
  • Performed simulations for customers on liquid propellant tank sloshing from lift-off through stage separation including effects of thrust oscillations
  • Analyzed tank sloshing under oscillatory thrust forces and side loads and calculated stability limits under various frequency and amplitudes

Solid Rocket Motors & Boosters

Solid rocket motors (SRMs) are used in a variety of tactical and strategic missile propulsion applications ranging from air-to-air missiles to cruise and ballistic missiles. Heavy-lift launch vehicles also employ SRMs as first stage boosters. Unlike liquid propellants, solid propulsion systems require no complicated engines or plumbing, and only rely on strong casings to withstand pressure. CFDRC has developed and applied physics-based modeling and simulation tools to analyze a variety of SRMs, to characterize motor performance, develop and mature propellant grain designs, and to evaluate nozzle flow fields.

Solid Rocket Motors & Boosters
  • Supported custoemrs in the assessment of Initial Over-Pressure (IOP) waves propagating from the Mobile Launch Platforms
  • Supported customers in the evaluation of Launch Vehicle motor design using various CFD simulation tools and technologies
  • Conducted grey gas, non-grey gas, and solid particle radiation modeling for SRM internal combustion chambers external plume radiation analysis, and base heating of the launch vehicle
  • Supported NASA in Space Shuttle Challenger RSRM O-Ring joint redesign (1987), and Columbia Return-to-Flight (2005) by providing high fidelity modeling & simulation

Missile Weather Encounter

Global and regional weather definition is critical to assessing future missile and projectile survivability relative to strategic placement and launch decision support. CFDRC has developed an Integrated Missile Weather Encounter Toolkit to characterize missile survivability relative to probabilistically defined aberrant weather encounters along a given flight path for various mission scenarios. This toolkit utilizes state of the art probabilistic, global, and regional weather information from multiple databases, including NASA’s Global Precipitation Climatology Project and NOAA’s Climate Prediction Center Morphing Methodology, NCAR’s Climate Four Dimensional Data Assimilation (CFDDA), and NCAR’s Regional Atmospheric Modeling System (RAMS).

Missile Weather Encounter
  • Prototype development to TRL 5 of an improved weather specification capability that provides greater regional weather characterization for missile specific flight parameters
  • Development of an interactive Visual Interface, with global map display, pan, zoom features; trajectory tools; 2D color maps for water content information, and hydrometeor distribution plots
  • Coupled weather data extraction capabilities with physics-based modeling tools for missile survivability prediction
  • Generation of customized weather databases for various regions of interest, useful for analyzing global climate change and localized climatology

High Speed Missile Maneuvering with DACS

At high altitudes and low ambient pressures, rocket plumes of missile Divert and Attitude Control System (DACS) jets expand much faster and wider than at sea level. The plume expansion may also interfere with the targeting sensors in the nose of the missile. CFDRC has performed numerous design studies of missile DACS systems, at various altitudes, from supersonic to hypersonic velocities, for solid, liquid and gelled propellants.

High Speed Missile Maneuvering with DACS
  • Hypersonic divert thruster jet interaction flow fields computed for an interceptor missile at high altitude hypersonic speeds
  • Performed design, development, and testing of proportional thrust control axial pintle valve technology for DACS applications, including trade studies to characterize system performance at altitude
  • 3D plume effects analysis to characterize varying interactions of missile boundary layer and base flow interactions with the plume, impacting the plume internal thermal structure, and missile signature