TY - JOUR

T1 - Highly underexpanded rarefied jet flows

AU - Bykov, N. Y.

AU - Gorbachev, Yu E.

AU - Fyodorov, S. A.

N1 - The work was completely performed at the Novosibirsk State University using the computational capabilities of the Peter the Great St.Petersburg Polytechnic University with the financial support of the Russian Science Foundation (grant no. 22‐11‐00080).

PY - 2023/8/9

Y1 - 2023/8/9

N2 - A highly underexpanded jet outflow into the background in transition and scattering regimes is studied computationally. The direct simulation Monte Carlo method and Navier–Stokes equations are used. The main parameters’ impact on the jet flow is analyzed. It is shown that a drastic flow structure transformation occurs in a relatively narrow Reynolds numbers’ range, 5 ≤ ReL ≤ 30, featuring the jet–surrounding gas interaction. At ReL = 5, a shock wave structure that is typical for the underexpanded jet degenerates completely. The existing empirical expressions application for the estimation of the characteristic dimensions of the shock wave structure in the transition regime leads to significant inaccuracy. For the considered parameters’ range, the approaches based on the direct simulation Monte Carlo method and Navier–Stokes (NS) equations’ solution lead to similar results in the nozzle region, where the flow regime is hydrodynamic. Nevertheless, the NS approach employment for the assessment of flow parameters within rarefied shock layers is debatable.

AB - A highly underexpanded jet outflow into the background in transition and scattering regimes is studied computationally. The direct simulation Monte Carlo method and Navier–Stokes equations are used. The main parameters’ impact on the jet flow is analyzed. It is shown that a drastic flow structure transformation occurs in a relatively narrow Reynolds numbers’ range, 5 ≤ ReL ≤ 30, featuring the jet–surrounding gas interaction. At ReL = 5, a shock wave structure that is typical for the underexpanded jet degenerates completely. The existing empirical expressions application for the estimation of the characteristic dimensions of the shock wave structure in the transition regime leads to significant inaccuracy. For the considered parameters’ range, the approaches based on the direct simulation Monte Carlo method and Navier–Stokes (NS) equations’ solution lead to similar results in the nozzle region, where the flow regime is hydrodynamic. Nevertheless, the NS approach employment for the assessment of flow parameters within rarefied shock layers is debatable.

KW - CFD

KW - DSMC

KW - nozzle flow

KW - rarefied gas

KW - shock wave structure

KW - underexpanded jet

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85168688206&origin=inward&txGid=74080be3123daba1f984e4e807be7e7a

UR - https://www.mendeley.com/catalogue/7dc583e6-4789-3a7c-808f-b8f555ac719f/

U2 - 10.3389/fmech.2023.1216927

DO - 10.3389/fmech.2023.1216927

M3 - Article

VL - 9

JO - Frontiers in Mechanical Engineering

JF - Frontiers in Mechanical Engineering

SN - 2297-3079

M1 - 1216927

ER -