Abstract
This paper presents the Eulerian–Lagrangian approach for numerical modeling of high-speed gas-droplet flows and aeroacoustics. The proposed hybrid approach is implemented using the OpenFOAM library and two different methods. The first method is based on a hybrid convective terms approximation method employing a Kurganov–Tadmor and PIMPLE scheme. The second method employs the regularized or quasi-gas dynamic equations. The Lagrangian part of the flow description uses the OpenFOAM cloud model. Within this model, the injected droplets are simulated as packages (parcels) of particles with constant mass and diameter within each parcel. According to this model, parcels moving in the gas flow could undergo deceleration, heating, evaporation, and breakup due to hydrodynamic instabilities. The far-field acoustic noise is predicted using Ffowcs Williams and Hawking’s analogy. The Lagrangian model is verified using the cases with droplet evaporation and motion. Numerical investigation of water microjet injection into the hot ideally expanded jet allowed studying acoustic properties and flow structures, which emerged due to the interaction of gas and liquid. Simulation results showed that water injection with a mass flow rate equal to 13% of the gas jet mass flow rate reduced the noise by approximately 2 dB. This result was in good coincidence with the experimental observations, where maximum noise reduction was about 1.6 dB.
Highlights
One of the most important problems in the aerospace field is the minimization of acoustic noise from jet engines [1]
The main source of noise from high-speed turbulent jets is hydrodynamic instabilities, which lead to the emergence of forces acting from the flow on the surrounding environment
Three methods of jet-noise prediction while accounting for water injection could be distinguished: semi-empirical models that combine a large amount of experimental data with the theory of similarity [15], methods of computational aero-gas-dynamics and acoustics using direct numerical simulation, and hybrid strategies
Summary
One of the most important problems in the aerospace field is the minimization of acoustic noise from jet engines [1]. Water injection into the hot gas jet zone is one of these methods This approach was studied in papers [6,7,8,9]. Three methods of jet-noise prediction while accounting for water injection could be distinguished: semi-empirical models that combine a large amount of experimental data with the theory of similarity [15], methods of computational aero-gas-dynamics and acoustics using direct numerical simulation, and hybrid strategies. Reduced order models were used to reduce computational costs for computational aero-acoustic problems [20,21] In these papers, coherent structures of jet flow were identified using the proper orthogonal decomposition method. The proposal in this work for solving the problem of determining acoustic noise from a supersonic jet, taking into account water injection, is based on the less resource-intensive Eulerian–Lagrangian approach. The opensource OpenFOAM package is selected as the main platform for the model implementation
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