Biomedical subjects

R I Sujith

Publications and source records attributed to R I Sujith.

4 recordsLinked to original sources

PubMed2003

Jet forking driven by pipe tone.

The present work deals with an experimental investigation of flow of air through a square-edged circular orifice at the downstream end of a circular duct. Self-excited acoustic oscillations at the natural duct modes are observed for certain flow velocities when the orifice is sufficiently thick. For a specific Reynolds number based on the orifice diameter and the mean jet velocity (9150 < Re < 9850), the jet forks into two trains, with the alternating vortices falling into the same branch of the forked train. Whereas this phenomenon has been reported earlier to have occurred when the density ratio of the jet is less than 0.72, the present results show that it is possible for a jet having the same density as the ambient atmosphere. The jet forking is coincident with jump in the acoustic frequency from one natural acoustic mode to another with comparable amplitudes of both the modes.

Journal Article↗

PubMed2003

Determination of unsteady heat release distribution from acoustic pressure measurements: a reformulation of the inverse problem.

An integral method is developed to solve the inverse problem of determining the oscillatory heat release distribution from the knowledge of the acoustic pressure field within a combustor. Unlike earlier approaches, in which the problem is formulated in terms of Fredholm integral equation, the inverse problem is reformulated in terms of Volterra integral equation. This reformulation, valid for low Mach numbers (M2 << 1), facilitates the recovery of heat release at all frequencies. The resulting Volterra integral equation is solved using both direct numerical method and implicit least-squares method. The results show that the implicit least-squares method is superior to the direct numerical method and yields accurate determination of heat release at all frequencies.

Journal Article↗

PubMed2001

Exact solutions for modeling sound propagation through a combustion zone.

Exact analytical solutions for one-dimensional sound propagation through a combustion zone, taking the effects of mean temperature gradient and oscillatory heat release into account, are presented in this paper. The wave equation is derived starting from the momentum and energy equations. Using appropriate transformations, solutions are derived for the case of an exponential mean temperature gradient in terms of Bessel functions. For the case of a linear mean temperature profile, solutions are derived in terms of confluent hypergeometric functions. Example calculations show that the accuracy in modeling combustion-acoustics interactions can be significantly increased by the use of these solutions.

Journal Article↗

PubMed2000

Exact solutions to one-dimensional acoustic fields with temperature gradient and mean flow.

An exact solution for one-dimensional acoustic fields in ducts in the presence of an axial mean temperature gradient and mean flow is presented in this paper. The analysis is valid for mean Mach numbers such that the square of the mean Mach number is much less than one. The one-dimensional wave equation for ducts with axial mean temperature gradient and mean flow is derived. By appropriate transformations, the wave equation is reduced to an analytically solvable hypergeometric differential equation for the case of a linear mean temperature profile. The developed solution is applied to investigate the dependence of sound propagation in a duct on factors such as temperature gradient and mean flow. The results obtained using the analytical solution compare very well with the numerical results. The developed solution is also compared with an existing analytical solution.

Acoustics↗