Numerical study of the flow and the near acoustic fields of an underexpanded round free jet generating two screech tones
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Citations
Wavepacket Modelling of Broadband Shock-Associated Noise in Supersonic Jets
A numerical study on near-field pressure fluctuations of symmetrical and anti-symmetrical flapping modes of twin-jet using a high-resolution shock-capturing scheme
Links Between Steepened Mach Waves and Coherent Structures for a Supersonic Jet
Spatiotemporal superresolution measurement based on POD and sparse regression applied to a supersonic jet measured by PIV and near-field microphone
Unstructured Large-Eddy Simulations of Rectangular Jet Screech: Assessment and Validation
References
A family of low dispersive and low dissipative explicit schemes for flow and noise computations
On the Mechanism of Choked Jet Noise
The sources of jet noise: experimental evidence
On the Two Components of Turbulent Mixing Noise from Supersonic Jets
Shock associated noise of supersonic jets from convergent-divergent nozzles
Related Papers (5)
Frequently Asked Questions (11)
Q2. What are the future works in "Numerical study of the flow and the near acoustic fields of an underexpanded round free jet generating two screech tones" ?
The convection velocity of large-scale structures in the jet shear layers is evaluated, and values similar to experimental data are found. The mixing noise component seems due to the sudden intrusion of turbulent structures into the potential core, near its end.
Q3. What is the strength of the forcing chosen?
The strength of the forcing is chosen in order to obtain turbulent intensities of around 6% of the fully expanded jet velocity at the nozzle exit.
Q4. How is the convection velocity at the nozzle exit?
the convection velocity is close to the value 0:35uj ’ 0:5ue at the nozzle exit, as expected for instabilities initially growing in the mixing layers just downstream of the nozzle.
Q5. What was the first to use schlieren pictures in experiments?
The results from this jet were also used to generate schlieren-like images, in a study of Castelain et al.,17 in order to asses the quality of the estimation of the convection velocity in the jet shear layers using schlieren pictures in experiments.
Q6. How many times did Raman43 observe two screech tones switching in time?
Fornon-ideally expanded jets exiting from a rectangular nozzle with a single-bevelled exit, Raman43 also observed two screech tones switching in time.
Q7. What is the central frequency of the broadband shock-associated noise?
the size of the sixth shock cell, Ls6 ¼ 2:35r0, located around z ¼ 15r0, is used in the relation (9) to compute the central frequency of the broadband shock-associated noise as a function of angle .
Q8. What is the mechanism of the broadband shock-associated noise?
In this mechanism, the broadband shock-associated noise is generated by the interactions between the turbulent structures propagating downstream in the jet shear layers and the shocks of the quasi-periodic shock cell structure.
Q9. What is the mean convection velocity of the cell structures in the jet?
In order to apply equation (8) to the simulated jet, the mean convection velocity is considered equal to 5 uc 4 ¼ 0:65uj in the region 5r0 5 z5 15r0, as suggested in Figure 12.
Q10. What is the frequency of the first mode of the broadband shock-associated noise?
For screeching jets, Tam et al.13 suggested that the central frequency of the first mode N¼ 1 of the broadband shock-associated noise tends to the screech frequency at ¼ 180 .
Q11. Where is the local convection velocity of the turbulent structures?
The local convection velocity of the turbulent structures is estimated at the center of the shear layer, where the velocity fluctuations are maximum, as presented in Figure 11.