Thursday, March 09, 2023 11:00AM

Brown Bag Seminar

Thursday, March 9, 2023

11:00 am – 12:00 pm

Guggenheim 442

Presenters:

 

Jesudunsin Awodele

Todd Goehmann 

Rashi Yadav

Jesudunsin Awodele

Title: Validation of CFD Solver: Aerodynamic Predictions for 2-D Flows

Abstract:

Generating accurate Computational Fluid Dynamics results is imperative to acquiring reliable data without needing to use a wind tunnel. While the Numerical Aerodynamic Simulation with Cartesian Grid Techniques (NASCART-GT) has the benefit of automatically generating meshes around a geometry, it becomes computationally expensive to run viscous simulations. Implementing the Discontinuous Galerkin method as an extension to NASCART-GT enables faster viscous simulations. To validate this extension, an inviscid exact solution to a Prandtl-Meyer expansion wave was computed to compare the root mean square (RMS) error of the solver with the RMS error of unstructured Ansys Fluent meshes. The RMS was compared as a function of grid density for the two solvers. The results yield that increasing the grid density decreases the error and that NASCART-GT consistently has a lower error than the comparable Ansys Fluent cases.

Advisor: Professor Stephen Ruffin

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Todd Goehmann 

Title:  Streamlining Whirl Flutter Prediction Considering Multiple Varying Parameters

Abstract: 

As tiltrotor, urban air mobility, and distributed electric propulsion aircraft become popular, there is a growing need for accurate and computationally efficient methods to predict whirl flutter. This phenomenon is a dynamic aeroelastic instability of wing-rotor or wing-proprietor systems caused by interactions between elastic, inertial, gyroscopic, and aerodynamic effects, which causes oscillations that may damage or destroy the aircraft. To avoid this issue, it requires methods to predict the whirl flutter onset and amplitude of post-flutter oscillations accurately and at a fraction of the computational cost of existing methods, which typically rely on a large number of transient simulations. This work investigated a new method that uses output data from as few as two transient simulations at forward speeds up to 30% away from the whirl flutter speed. The method predicts the whirl flutter onset and amplitude of post-flutter oscillations of an isolated rotor benchmark model within few percentages of reference results without requiring transient responses at dozens of flight conditions. The new method also enables computationally efficient flight envelope exploration for multiple simultaneously varying parameters (such as forward speed and altitude) with no loss in accuracy. This method can help predict whirl flutter earlier in the design cycle of new tiltrotor, urban air mobility, and distributed electric propulsion aircraft to develop lighter and faster configurations while avoiding dangerous instabilities.

Advisor: Professor Cristina Riso

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Rashi Yadav

Title: Laser-Induced Incandescence

Abstract: 

Laser-induced incandescence (LII) is a technique used for measuring particle size and concentration in a gas phase. It works by using a laser to heat up a particle in a gas, causing it to incandesce or emit light, which is then captured using a camera and analyzed. LII can be used in many applications such as soot and particle measurements in combustion systems, environmental testing, and material science research. It is a non-intrusive method. Thus, it does not interfere with the gas flow or the particles being measured. This method is applied in the Ascent 70 project to detect the size and makeup of soot particles produced during a combustion event. The analysis is done on varying fuel ratios, as well as internal temperatures and pressures to analyze soot production in different conditions. Soot is composed of a complex ratio of carbon-based particles that are produced during the combustion of fossil fuels and other organic materials. LII helps us understand the formation and characteristics of soot which is key for improving the efficiency and reducing the emissions of combustion systems. The intensity of the incandescent light emitted by the soot particles is directly related to their temperature and size. By analyzing the spectral and temporal characteristics of the emitted light in this project, we obtain quantitative data on soot volume fraction, particle size, and particle number density.

Advisor: Professor Ellen Mazumdar