Data-driven Pressure Recovery in Diffusers

TL;DR

This study combines experimental, numerical, and data-driven optimization techniques to enhance pressure recovery in S-shaped diffusers through optimal mass injection frequency and flow control.

Contribution

It introduces a data-driven retrospective cost optimization method for diffuser pressure recovery, validated through experiments and high-fidelity simulations.

Findings

Optimal injection frequency between 100-300 Hz identified

Numerical simulations agree well with experimental data

Data-driven control improves pressure recovery and flow stability

Abstract

This paper investigates the application of a data-driven technique based on retrospective cost optimization to optimize the frequency of mass injection into an S-shaped diffuser, with the objective of maximizing the pressure recovery. Experimental data indicated that there is an optimal injection frequency between 100 Hz and 300 Hz with a mass flow rate of 1 percent of the free stream. High-fidelity numerical simulations using compressible unsteady Reynolds-Averaged Navier-Stokes (URANS) are conducted to investigate the mean and temporal features resulting from mass injection into an S-shaped diffuser with differing injection speeds and pulse frequencies. The results are compared with experiments to confirm the accuracy of the numerical solution. Overall, 2-D simulations are relatively in good agreement with the experiment, with 3-D simulations currently under investigation to benchmark the effect of spanwise instabilities. Simulation results with the proposed data-driven technique show improvements upon a baseline case by increasing pressure recovery and reducing the region of flow recirculation within the diffuser.