Analysis of Flame Deflector Spray Nozzles in Rocket Engine Test Stands

Abstract

The development of a unified tightly coupled multi-phase computational framework is described for the analysis and design of cooling spray nozzle configurations on the flame deflector in rocket engine test stands. An Eulerian formulation is used to model the disperse phase and is coupled to the gas-phase equations through momentum and heat transfer as well as phase change. The phase change formulation is modeled according to a modified form of the Hertz-Knudsen equation. Various simple test cases are presented to verify the validity of the numerical framework. The ability of the methodology to accurately predict the temperature load on the flame deflector is demonstrated though application to an actual sub-scale test facility. The CFD simulation was able to reproduce the result of the test-firing, showing that the spray nozzle configuration provided insufficient amount of cooling.

Multiphase Modeling of Water Injection on Flame Deflector

“…The water cooling would have been more effective if it were installed along the MFD, as shown in another study. 7 It is possible that the water jet angle can also have a cooling effect. For that reason, the water nozzles might need to be canted to a larger angle downward.…”

Liquid jet penetration and breakup in a free supersonic gas jet

“…In addition, there are water suppression systems which act to preserve test stand structure by providing a shielding water sheet to protect from radiative cooling, but they are not the subject of this work. [3] As the proper design of such a system necessitates the analysis of a highly chaotic multiphase flow, computational fluid dynamics (CFD) methods have been leveraged by NASA engineers to be able to understand the complex behavior of these systems to design systems which are inherently safe and reliable. The CFD codes also permit optimization studies to evaluate cooling spray configurations that can provide optimal performance by utilizing the least amount of water for a rocket test.…”

“…Figure 3. Left: CFD results for gas phase, liquid phase, combined phases, Right: Results for cooled plate [3] Though promising results have been achieved for the global results of a computationally designed cooling system's ability to predict the cooling effects and locations, verifying the ability of the code to predict the breakup behavior of the liquid phase and understanding its interaction with the shock structure at the nozzle exit are rendered nearly impossible in the actual rocket tests at SSC. This is due to the highly chaotic, extremely harsh testing environment which makes it very difficult to conduct detailed qualitative and quantitative measurements of local flow properties that are needed to reliably verify the CFD code.…”

“…While a number of simulation studies have been performed to study water injection into rocket exhaust including work in [3], [4], [12], [22], and [23], experimental studies are scarce and testament to the difficult test conditions. One study to note is by Liwu et al [6] and later by Zhou et al [7] who investigated water injection into the exhaust plume of a solid rocket motor.…”

Space Shuttle Solid Rocket Motor Plume Pressure and Heat Rate Measurements

“…This protection scheme is used by the Ste,nnis B-1 Space Shuttle Main Engine (SSME) test stand . 13 At that test stand water is injected through numerous holes to protect the steel flame deflector from the SSME exhaust. …”