Session: 11-17-01: Micro/Nanofluidics 2025 - Fluid Engineering in Micro- and Nanosystems

Paper Number: 167267

Solution of Unsteady Compressible Flow Equations for High Speed Oscillating / Pulsating Flows and High Energy Blast Wave Propagations 

While it is recognized that research, study, analysis, prediction, and/or theoretical solutions of high speed oscillating compressible flows, muzzle blasts, and nuclear explosion blast wave propagations are exceedingly complex tasks, it is also recognized that further advances in the state-of-the-art in such areas and related devices and their applications can best be achieved through basic efforts and analysis utilizing insights developed from phenomenological understanding and empirical information. An effort is made here to obtain time dependent solutions. The approach is based on unsteady viscous and heat conducting compressible flow model as applied to analyzing the highly complex resonance tube heating phenomenon.

The resonance tube consists of a hollow cylinder (closed at one end) and an excitation nozzle.  It functions when the open end of the cylinder is placed in the compression region of a free jet emanating from the nozzle.  The periodic compression and expansion of the gas, within the rigid cavity of the tube, produce irreversible temperature increases several times the initial adiabatic temperature head.  The thermal energy generated by this process appears to be concentrated on the closed end of the tube and can be utilized to initiate exothermal processes requiring elevated temperature and/or heat flux as the initiation mechanism.  Military systems have seen its implementation for pyrotechnic initiation.  The fluidic nature, with intrinsic invulnerability to hostile environments, has given the application greater impetus.

A solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube has been obtained numerically, assuming one dimensional, viscous, and heat conducting flow, by solving the appropriate fluid dynamic and energy equations.  The tube is approximated by a right circular cylinder closed at one end with a piston oscillating at very high resonant frequency at the other end. An iterative implicit finite difference scheme is employed to obtain the solution.  The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties.  The solution would also be valid for tapered tubes if the variations in the cross-sectional area are small.  In successfully predicting the time dependent results, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems.  The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, and fluidic pyrotechnic initiation devices.  It can further be easily extended to cover muzzle blasts and nuclear explosion blast wave propagations in one dimensional and/or radial spherical coordinates with or without including energy generation / addition terms.

Presenting Author: Ramlala Sinha Applied Engineering Consultants

Presenting Author Biography: President, Senior Executive, Director of Engineering, IT and Software Development Manager, Multi-Program Manager of Diverse Range of Large Critically Important High-Priority National Programs, Research and Development Engineer, Senior Scientist, Developed Numerous Computer Codes / Software Programs, Authored Numerous Scientific and Technical Publications, etc.

Authors:

Ramlala Sinha Applied Engineering Consultants