Aerospace Engineering Brown Bag Lecture Series, Adhiraj Bhagat, Melam Master, and Brendan Mindiak

The April 1st AE Brown Bag Presentation featured Adhiraj Bhagat, Melam Master, and Brendan Mindiak
Melam Master presented: "Prediction of Forces and Moments of Canonical Shapes"
When it comes to aerodynamic analysis of agile unmanned aerial vehicles (UAVs), there is an obvious lack of research of fuselage aerodynamics. Current practices involve assuming the vehicle is a point-mass object and frontal equivalent flat plate drag equation, both of which are inaccurate. In the present work, an alternate solution is being developed. The Complex Aerodynamic Shape Simulator (COMPASS) can accurately perform aerodynamic analysis of the fuselage of agile UAVs up to five orders of magnitude less computationally costly than computational fluid dynamics (CFD). This simulator deconstructs the complex shape into canonical shapes: prisms, cylinders, spheres, etc. in order to obtain the quasi-steady aerodynamic coefficients of the fuselage. In the present work, two new shapes are being added to the simulation process: the spheroid and the flat plate. While the current simulation of these shapes is inaccurate due to the lack of sufficient data, future data collection will help provide a more accurate empirical formulation for the calculation of the aerodynamic coefficients
Brendan Mindiak presented: "Modeling Thermoacoustic Instabilities in Combustor Rigs"
In modern engine design, one problem that plagues many promising designs is a tendency for the internal system pressure to rapidly inflate such that the combustor system is damaged or even destroyed. This outcome is the product of competing pressure waves, or thermoacoustic instabilities. These instabilities can be difficult to predict but detrimental to the success of a combustor rig. Therefore, this project aims to improve upon the current modeling technique to be better able to predict the amplitude of these instabilities, thus providing insight into the success of a rig without relying on full-scale testing. A pre-existing data set for a can-annular rig, provided by Jeong-Won Kim, relied on pressure transducers located azimuthally throughout the rig to be able to visualize the pressure amplitude as a function of time. Using this data set, complex reduction methods were applied that would allow a 3-D wave equation based only on measurable testing conditions to be fit to the pre-existing data. This model was found to be successful in modeling the pre-existing data set, but additional data collection is recommended to further verify the produced results to predict the pressure amplitudes in these rigs
Adhiraj Bhagat presented: "Laser Diagnostic Methods for Turbulent Premixed Combustion in a Swirl Stabilized Combustor"
Turbulent premixed combustion is widely used in engines for aerospace and automobile applications and stationary gas turbines. Although the effects of turbulence on premixed flames have been studied before, the effects of combustion on turbulence characteristics have received considerably less attention, especially at highly turbulent flow conditions characteristic in practical devices. Most studies have used direct numerical simulations to observe these effects which are computationally expensive, are limited to low Reynolds number flows, and commonly do not consider the effects of realistic flows like geometry. Experimental measurements of turbulence characteristics are commonly acquired using laser-based diagnostic methods. This presentation will discuss the diagnostic methods - tomographic particle image velocimetry and planar laser induced fluorescence - and their experimental setup; these are used to measure the high-resolution 3D velocity field and the planar distribution of formaldehyde in the flame of a swirl-stabilized combustor.