Measurement of hybrid rocket solid fuel regression rate for a slab burner using deep learning. (January 2022)

• Record Type: Journal Article
• Authors: Surina, Gabriel; Georgalis, Georgios; Aphale, Siddhant S.; Patra, Abani; DesJardin, Paul E.
• Is Part Of: Acta astronautica. Volume 190(2022)
• Page Start: 160
• Page End: 175
• Publication Date: 2022-01
• Subjects: Hybrid fuel -- Regression rate measurement -- Convolutional neural network -- Monte-Carlo dropout -- Model uncertainty; Astronautics -- Periodicals; Outer space -- Exploration -- Periodicals; Astronautics; Periodicals; 629.405
• DOI: 10.1016/j.actaastro.2021.09.046
• Languages: English
• ISSNs: 0094-5765

Abstract

Abstract: This study presents an imaging-based deep learning tool to measure the fuel regression rate in a 2D slab burner experiment for hybrid rocket fuels. The slab burner experiment is designed to verify mechanistic models of reacting boundary layer combustion in hybrid rockets by the measurement of fuel regression rates. A DSLR camera with a high intensity flash is used to capture images throughout the burn and the images are then used to find the fuel boundary to calculate the regression rate. A U-net convolutional neural network architecture is explored to segment the fuel from the experimental images. A Monte-Carlo Dropout process is used to quantify the regression rate uncertainty produced from the network. The U-net computed regression rates are compared with values from other techniques from literature and show error less than 10%. An oxidizer flux dependency study is performed and shows the U-net predictions of regression rates are accurate and independent of the oxidizer flux, when the images in the training set are not over-saturated. Training with monochrome images is explored and is not successful at predicting the fuel regression rate from images with high noise. The network is superior at filtering out noise introduced by soot, pitting, and wax deposition on the chamber glass as well as the flame when compared to traditional image processing techniques, such as threshold binary conversion and spatial filtering. U-net consistently provides low error image segmentations to allow accurate computation of the regression rate of the fuel. Highlights: Accurate regression rate measurement using U-net neural network for a slab burner. Network is superior at filtering out noise compared to other basic image processing. U-net neural network is shown to be independent of incoming oxidizer mass flux. Model-generated regression rate uncertainty is quantified using Monte-Carlo Dropout.