Numerical Study on Sonic
Underexpanded Co-flowing Jet
with Varying Separation Distance
R. Naren Shankar, K. Sathish Kumar, N. Dilip Raja, J. Sumendran,
Nishant Kumar Raj, Purushottam Kumar Yadav, S. Smruthi,
and Krishna Kumar Gosain
Abstract Mixing characteristics of sonic under expanded co-flowing jets are analysed with varying separation distance. The separation distance is defined as the
distance separating the primary and secondary nozzles. The varying separation
distance is understood as a passive way to control a jet. Reduced separation distance
value of 3 mm and a dominant separation distance value of 15 mm is used in the
current study. The nozzle pressure ratio chosen for the study is 5. The centreline
total pressure decay, contours of total pressure, Mach number, density gradient, and
turbulent kinetic energy were studied. The present study has been validated with
experimental results available in the open literature. Results show that the secondary
jet elongates the primary jet potential core length for the reduced lip 3 mm because
the surrounding jet shields the central jet. The potential core length for the dominant lip 15 mm is reduced because the surrounding jet vigorously interacts with
the central jet due to increased lip thickness. The contours show the jet mixing
phenomena such as the wake region, sub-atmospheric region, recirculation zone and
shock crossover, Mach disc, Shear layer amidst jets, shear layer between surrounding
jet and atmosphere. The characteristics like potential core region, jet spread, Primary
and secondary jet interaction and sub-atmospheric region are studied.
Keywords Sonic under expanded · Co-flowing jet · Separation distance
R. Naren Shankar (B) · N. Dilip Raja · J. Sumendran · N. K. Raj · P. K. Yadav · S. Smruthi ·
K. K. Gosain
Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology,
Outer Ring Road, Avadi, Chennai, Tamil Nadu 600062, India
e-mail: narensankar@veltech.edu.in
N. K. Raj
e-mail: vtu8056@veltechuniv.edu.in
S. Smruthi
e-mail: vtu10147@veltechuniv.edu.in
K. Sathish Kumar
P.B. College of Engineering, Irungattukottai, Chennai, Tamil Nadu 602117, India
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2021
N. Gascoin and E. Balasubramanian (eds.), Innovative Design, Analysis
and Development Practices in Aerospace and Automotive Engineering, Lecture Notes
in Mechanical Engineering, https://doi.org/10.1007/978-981-15-6619-6_39
359
Underexpanded Co-flowing Jet
with Varying Separation Distance
R. Naren Shankar, K. Sathish Kumar, N. Dilip Raja, J. Sumendran,
Nishant Kumar Raj, Purushottam Kumar Yadav, S. Smruthi,
and Krishna Kumar Gosain
Abstract Mixing characteristics of sonic under expanded co-flowing jets are analysed with varying separation distance. The separation distance is defined as the
distance separating the primary and secondary nozzles. The varying separation
distance is understood as a passive way to control a jet. Reduced separation distance
value of 3 mm and a dominant separation distance value of 15 mm is used in the
current study. The nozzle pressure ratio chosen for the study is 5. The centreline
total pressure decay, contours of total pressure, Mach number, density gradient, and
turbulent kinetic energy were studied. The present study has been validated with
experimental results available in the open literature. Results show that the secondary
jet elongates the primary jet potential core length for the reduced lip 3 mm because
the surrounding jet shields the central jet. The potential core length for the dominant lip 15 mm is reduced because the surrounding jet vigorously interacts with
the central jet due to increased lip thickness. The contours show the jet mixing
phenomena such as the wake region, sub-atmospheric region, recirculation zone and
shock crossover, Mach disc, Shear layer amidst jets, shear layer between surrounding
jet and atmosphere. The characteristics like potential core region, jet spread, Primary
and secondary jet interaction and sub-atmospheric region are studied.
Keywords Sonic under expanded · Co-flowing jet · Separation distance
R. Naren Shankar (B) · N. Dilip Raja · J. Sumendran · N. K. Raj · P. K. Yadav · S. Smruthi ·
K. K. Gosain
Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology,
Outer Ring Road, Avadi, Chennai, Tamil Nadu 600062, India
e-mail: narensankar@veltech.edu.in
N. K. Raj
e-mail: vtu8056@veltechuniv.edu.in
S. Smruthi
e-mail: vtu10147@veltechuniv.edu.in
K. Sathish Kumar
P.B. College of Engineering, Irungattukottai, Chennai, Tamil Nadu 602117, India
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2021
N. Gascoin and E. Balasubramanian (eds.), Innovative Design, Analysis
and Development Practices in Aerospace and Automotive Engineering, Lecture Notes
in Mechanical Engineering, https://doi.org/10.1007/978-981-15-6619-6_39
359