Current work in combustion and related studies has focused on three areas: computational simulations of combustion instabilities in the hybrid class of rockets, investigation of new fuel additives for the hybrid rocket, and investigations of small arms firing. The hybrid class of rocket motors uses a solid fuel with gaseous oxygen which is introduced into the combustion chamber. Experimentally, several ideas have been proposed to explain chamber pressure pulsing, which are also seen in thrust and plume spectral diagnostics. Under development are computational simulations which will benefit from the use of high-speed video techniques. Comparing computer-generated animated predictions with actual experimental high-speed recordings allows the direct critique of modeled results. Thus, a unique feedback mechanism not currently available in computational simulations will be available to improve the quality of research. Currently, the research group is working to develop a CFD code which models the cylindrical motor. Effects such as the kinetic and chemical interaction of the fuel/oxidizer layer are a main feature which will be modeled. Pressure, temperature, chemical components, turbulence, char layers and combustion instabilities will all be investigated through the model.

Using the advanced graphics capabilities of the laboratory, research work includes molecular modeling predictions of combustion at the molecular level, and further, to an understanding of the effect on the polymer matrix. Real-time high-speed video will allow viewing of the combustion surfaces using laboratory combustion chambers and the in-house "slab" hybrid motor. These videos will be compared with simulated graphical outputs. Information revealed enables researchers to judge more precisely the performance of each fuel additive.

UALR will also be providing instrument measurements to validate NASA CFD hybrid rocket codes for U.S. Environmental Protection Agency (EPS) approval. Work will involve codes being run remotely to perform the analyses with results transferred between UALR and NASA Stennis for post-processing and comparison with experimental data. Post-processed results will be sent back to NASA. Live video of the rocket motor firings will be possible through Internet 2 and will allow NASA engineers to observe test procedures and guide the testing. NASA has indicated that its engineers are placing more cameras on the Space Shuttle main engine tests because analysts can see phenomena in the plume which helps in the interpretation of the data channels. NASA is performing 3-D mapping of the plumes based on these cameras. A similar setup will be established at UALR for use with its hybrid rocket motor test facility. The work is of significance to NASA since NASA must satisfay the EPA that large-scale firings of the hybrid rocket motors will not emit toxic substances in unacceptable levels. Currently, NASA is using unvalidated simulations which result in large factors of safety and higher costs per run. With UALR’s validation CFD codes using experimental data, NASA can proceed with more reasonable factors of safety.

CFD modeling has been used to predict the sound pressure levels in the firing of various small arms and to predict the effect of suppression devices. This is important when hearing loss in soldiers is considered and in clandestine military activities. The Small Arms Test Lab has been used to gather standard ballistic data, such as chamber pressure, velocity, and sound pressure levels. Work has also been started to collect muzzle flash data and primer performance characteristics and to correlate these data with the ballistics data. The capability of capturing muzzle flash or primer combustion flash via high speed video, in addition to the ballistic data, will greatly enhance the comparison of data to the modeled results. Again, the comparison will allow refinements based on physical experimental data to be introduced into the computational model. Transmission of data, refinements of models, and sharing of high-speed video of experimental set ups is necessary for the progress of the research but not convenient currently due to bandwidth and quality of service constraints.