DSMC grid methodologies for computing low-density, hypersonic flows about reusable launch vehicles

Richard, G Wilmoth; Gerald, J LeBeau; Ann, B Carlson

doi:10.2514/6.1996-1812

Cited by 30 publications

(16 citation statements)

References 9 publications

(10 reference statements)

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“…The DSMC results are provided in [11]. The DSMC model consists of a triangular plate mesh of varying resolution [9][10][11] with mean and median element areas of approximately 12 and 1 cm 2 , respectively. The FreeMat model was run with a mean element area of approximately 8 cm 2 .…”

Section: Mars Reconnaissance Orbiter Applicationmentioning

confidence: 99%

Improved Method for the Estimation of Spacecraft Free-Molecular Aerodynamic Properties

Fuller

Tolson

2009

Journal of Spacecraft and Rockets

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A numerical procedure for calculating free-molecular aerodynamic properties of spacecraft is revisited and redeveloped using improved discretization and shading techniques. New complex geometric shapes are included, allowing the user to model a high-fidelity spacecraft model divisible into elemental panels of approximately equal area to conserve resolution. The forces on exposed elements are summed across the entire geometry. New analytic methods for determining exposed panels have been developed. Combined with the use of array algebra, the improvements considerably enhance processing speeds. The fidelity of the data is tested by application to the geometry of the Mars Reconnaissance Orbiter. The resulting data are compared with direct simulation Monte Carlo predictions. Additional case studies serve to inspect implications of geometry design versus output accuracy and processing speed.= moment coefficient about the y axis C Mz = moment coefficient about the z axis F n;e = normal elemental force F t;e = tangential elemental force k = Boltzmann constant m = atmospheric mean molecular mass S = molecular speed ratio T = freestream temperature T w = average spacecraft surface temperature U = flow velocity = aerodynamic pitch angle = aerodynamic yaw angle " n , " t = normal and tangential components of unit flow vector to element = flow incidence angle = atmospheric density n , t = normal and tangential momentum accommodation coefficients

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Section: Mars Reconnaissance Orbiter Applicationmentioning

confidence: 99%

Improved Method for the Estimation of Spacecraft Free-Molecular Aerodynamic Properties

Fuller

Tolson

2009

Journal of Spacecraft and Rockets

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“…21,22 The code uses an unstructuredtriangulargrid for surface representation,which is embedded in a two-levelCartesian ow eld grid that provides a grid adaptation capability. The domains used in the DSMC simulations include the EMP spacecraft up to the plane of the pressure sensor.…”

Section: Rare Ed Plume Flowmentioning

confidence: 99%

Simulations of Cold-Gas Nozzle and Plume Flows and Flight Data Comparisons

Gatsonis

Nanson

LeBeau

2000

Journal of Spacecraft and Rockets

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The nozzle and plume ows of small cold-gas attitude control thrusters, plume interactions with spacecraft surfaces, and the induced pressure environment are investigated numerically. The motivation for this study originates from pressure measurements that exhibited nonperiodic pulses during the rings of small cold-gas thrusters onboard a suborbital spacecraft. Pitch, yaw, and roll cold-gas thrusters were located on the 0.56-m-diam base of the spacecraft. The conical spacecraft ew at altitudes between 670 and 1200 km and carried inside a pressure sensor connected to the side surface with a tube. Predictions of the pressure inside the sensor chamber are obtained using a semi-analytical model with inputs from coupled continuum and kinetic simulations. The nozzle and plume ows for each thruster are simulated using a three-dimensional Navier-Stokes solver until breakdown. Flow eld properties inside the breakdown surface are used as inputs to the direct simulation Monte Carlo calculations in a domain that includes the spacecraft geometry. Flow eld properties at the entrance of the sensor tube are used as inputs to an analytical model to obtain the pressure inside the sensor chamber. Simulationsshow plume expansion, re ection off the spacecraft surfaces, and back ow. Pressure predictions for the pitch and yaw thruster plumes that reach the sensor after expanding on the spacecraft base are in very good agreement with measurements. Pressure induced by the roll thrusters is shown to be very sensitive to their radial position at the Environmental Monitor Package base and decreases with decreasing radial distance. Pressure overprediction of the roll thrusters is attributed to possible difference between the simulated and actual radial position.Nomenclature C m = most probable random speed at the pressure-sensor tube entrance, m/s D e = exit diameter of nozzle, mm D t = diameter of pressure-sensor tube, m D th = throat diameter of nozzle, mm Kn = Knudsen number L t = length of pressure-sensor tube, m M = Mach number P = Bird's breakdown parameter P C = pressure inside pressure-sensorchamber, Pa P E = pressure at the entrance of the pressure-sensor tube, Pa P 0 = stagnation pressure, kPa Re = Reynolds number S = ratio of mean speed to most probable random speed T C = temperature in the pressure-sensor chamber, K T E = temperature at the entrance of the pressure-sensor tube, K T w = wall temperature, K T 0 = stagnation temperature, K U E = mean speed at the entrance of the pressure-sensor tube, m/s x, y, z = coordinates used in the simulations a E = angle of attack at the entrance of the pressure-sensor tube, deg b = polar angle of the pressure-sensor tube entrance, deg k = mean-free path, m

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“…1,2 In DAC, the gas molecular collisions are modeled using the variable-hard-sphere (VHS) model developed by Bird 3 , and the Larsen-Borgnakke model is used for internal energy exchanges. The geometry surface is represented by unstructured triangular elements that are embedded in a two-level Cartesian grid for the flow field calculation.…”

Section: Methodsmentioning

confidence: 99%

Aeroheating Analysis for the Mars Reconnaissance Orbiter with Comparison to Flight Data

Liechty

2006

36th AIAA Fluid Dynamics Conference and Exhibit

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The aeroheating environment of the Mars Reconnaissance Orbiter (MRO) has been analyzed using the Direct Simulation Monte Carlo and free-molecular techniques. The results of these analyses were used to develop an aeroheating database to be used for the pre-flight planning and the in-flight operations support for the aerobraking phase of the MRO mission. The aeroheating predictions calculated for the MRO include the heat transfer coefficient ( C H ) over a range of angles-of-attack, side-slip angles, and number densities. The effects of flow chemistry were also investigated. Flight heat flux data deduced from surface temperature sensors have been compared to pre-flight predictions and agree favorably.

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DSMC grid methodologies for computing low-density, hypersonic flows about reusable launch vehicles

Cited by 30 publications

References 9 publications

Improved Method for the Estimation of Spacecraft Free-Molecular Aerodynamic Properties

Improved Method for the Estimation of Spacecraft Free-Molecular Aerodynamic Properties

Simulations of Cold-Gas Nozzle and Plume Flows and Flight Data Comparisons

Aeroheating Analysis for the Mars Reconnaissance Orbiter with Comparison to Flight Data

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