The Flame Deflector and Five Segment Booster By: Geoffrey Husk

The Flame Deflector Current Configuration Current Configuration

The Flame Deflector Major areas of concern revolve around deterioration of the deflector’s exit edge, the trench floor near the deflector, and the trench walls near the deflector Major areas of concern revolve around deterioration of the deflector’s exit edge, the trench floor near the deflector, and the trench walls near the deflector Deflector’s exit edge Trench Walls Trench Floor

Analysis Single Five Segment Booster Single Five Segment Booster SRB side of the Flame Deflector SRB side of the Flame Deflector –Current angle ( ) –Varying Deflector angle (40 0 – 55 0 ) Flame Trench Flame Trench –Current Geometry

Computational Fluid Dynamics (CFD) Preprocessor Preprocessor –GAMBIT Processor Processor –FLUENT Postprocessor Postprocessor –FLUENT

Outlet Control Volume, Boundaries, and “Mesh” Deflector Nozzle Inlet Floor Trench Walls MLP Floor

Solving Solves the integral form of the Navier Stokes equation in three dimensions Solves the integral form of the Navier Stokes equation in three dimensions –Mixed elliptic and parabolic differential equations Fluid: Air Fluid: Air –Sea-level properties Nozzle flow: 2530 m/s (1.6 mi/s or Mach 7.4) Nozzle flow: 2530 m/s (1.6 mi/s or Mach 7.4)

Results Pressure on the deflector’s lower edge Pressure on the deflector’s lower edge Pressure on the trench floor Pressure on the trench floor Pressure on the trench walls Pressure on the trench walls

The max pressure on the lower edge is approximately 51% of the highest pressure experienced directly under the rocket flow

The floor 6 feet from the deflector sees approximately 42% of the max pressure Negative pressure, along with re-circulating flow

For a small area on the trench walls near the end of the deflector and about 5 feet away from it we see approximately 45% of the max pressure

Results The pressure on the deflector’s exit edge is higher in the center, but there is significant pressure loading traversing the entire edge length The pressure on the deflector’s exit edge is higher in the center, but there is significant pressure loading traversing the entire edge length The pressure loads on the floor is also concentrated in the middle, but the loading off center is considerably lower The pressure loads on the floor is also concentrated in the middle, but the loading off center is considerably lower The loading on the trench walls seem to be localized to small areas near the bottom of the deflector, with the significant loading developing about midway up the deflector The loading on the trench walls seem to be localized to small areas near the bottom of the deflector, with the significant loading developing about midway up the deflector

Results Comparison to different geometry configurations Comparison to different geometry configurations –The deflector’s exit edge Loading from 40 to degree configurations varies slightly Loading from 40 to degree configurations varies slightly –The trench floor Loading increases as the angle increases from 20% max pressure at 40 0 to 42% at degrees Loading increases as the angle increases from 20% max pressure at 40 0 to 42% at degrees –The trench walls Loading varies slightly Loading varies slightly

Geometry Comparisons Deflector Edge 40 degrees 40 degrees –40% 45 degrees 45 degrees –36% 50 degrees 50 degrees –53% 55 degrees 55 degrees –47% degrees degrees –51% Trench Floor 40 degrees 40 degrees –20% 45 degrees 45 degrees –29% 50 degrees 50 degrees –29% 55 degrees 55 degrees –34% degrees degrees –42% Trench Walls 40 degrees 40 degrees –45% 45 degrees 45 degrees –46% 50 degrees 50 degrees –44% 55 degrees 55 degrees –46% degrees degrees –45%

Other considerations not modeled Shear stress from viscosity Shear stress from viscosity –Only the laminar case presented here –Turbulent case is a better representation Temperature Temperature –Conservation of Heat Equations Reacting Flow Reacting Flow Slag Deposits (Aluminum Perchlorate, “Black Beauty”) Slag Deposits (Aluminum Perchlorate, “Black Beauty”)

Conclusion With a qualitative study we see potential problems forming With a qualitative study we see potential problems forming To fully understand the magnitude a more quantative model needs to be developed To fully understand the magnitude a more quantative model needs to be developed –Under-expanded rocket blast –Fluid: SRB exhaust –Turbulence

What’s next? Deterioration Deterioration –Investigate the turbulent boundary layer and shear stress –Temperature/Heat model –Reacting Flow Contamination Contamination –Reacting Flow –Slag Deposits