Abstract
The slightly underexpanded free jet issued from a supersonic micro nozzle with a design Mach number of 1.5 and a square shape of 1 mm × 1 mm at the nozzle exit has been experimentally investigated using the rainbow schlieren deflectometry combined with the computed tomography where the nozzle operating pressure ratio is held constant at 4.0. Density fields in the free jet obtained from the rainbow schlieren deflectometry are the vortex sheet theory proposed by Tam. It is shown that there is good quantitative agreement between experiment and theory. It is shown that the rainbow schlieren deflectometry is a useful tool for studying the three-dimensional structure of shock containing free jets from micro-scale supersonic nozzles.
Highlights
In recent years, the design and fabrication of a microelectro mechanical system (MEMS) has increased the need for an understanding of fluid flow in microscale devices including inkjet printers, small satellite thrusters, critical nozzles at low Reynolds numbers and flowmeters of next-generation fuel cell vehicles (FCV)
The Reynolds-averaged Navier-Stokes simulation or large eddy simulation often becomes effective tools to investigate the physical properties in various areas such as aerospace and mechanical engineering because of cost curtailment and time saving. Such numerical simulations include turbulent models to close the governing equations. The capability of these models in simulating a complex physical phenomenon must be ascertained before the numerical results can be accepted
Numerical results are usually validated by comparing them with reliable experimental data
Summary
The design and fabrication of a microelectro mechanical system (MEMS) has increased the need for an understanding of fluid flow in microscale devices including inkjet printers, small satellite thrusters, critical nozzles at low Reynolds numbers and flowmeters of next-generation fuel cell vehicles (FCV). The Reynolds-averaged Navier-Stokes simulation or large eddy simulation often becomes effective tools to investigate the physical properties in various areas such as aerospace and mechanical engineering because of cost curtailment and time saving. Such numerical simulations include turbulent models to close the governing equations. It is found that the rainbow schlieren deflectometry combined with the computed tomography is a very efficient tool to measure three-dimensional density fields of shock-containing free jets from micro nozzles and to validate numerical simulation codes
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