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Journal ArticleDOI

A Parametric Study on the Fluid Dynamics and Performance Characteristic of Micronozzle Flows

01 Mar 2022-Journal of Fluids Engineering-transactions of The Asme (American Society of Mechanical Engineers Digital Collection)-Vol. 144, Iss: 3
TL;DR: In this paper, the fluid dynamics and performance characteristics in micronozzle flows with changes in various geometric parameters using Navier-Stokes simulation based on slip wall boundary conditions were investigated.
Abstract: This study investigates the fluid dynamics and performance characteristics in micronozzle flows with changes in various geometric parameters using Navier–Stokes simulation based on slip wall boundary conditions. The various geometric parameters considered for the study are (1) area ratio with fixed throat dimension and (2) the semidivergence angle variation with no change in area ratio. The simulation results show that the flow choking for micronozzle happens not at the geometric throat; rather pushed downstream to the divergent channel of the nozzle. This is due to the thick boundary layer growth, which reduces the effective flow area and shifts the minimum allowable flow area downstream to the throat. The distance to which the choking point shifts downstream to the throat reduces with Maxwell's slip wall conditions compared to the conventional no-slip wall condition. The downstream movement of the choking point from the throat reduces with an increase in area ratio and with increase in divergence angle with fixed area ratio. This is due to the fact that the increase in area ratio and divergence angle increases the nozzle height at any particular section in the divergent portion of the nozzle. As a result of this, the boundary layer profile also moves upward and the restriction of potential core by the thick boundary layer reduces, which in turn leads to an increase in the effective minimum flow area downstream to the throat.
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TL;DR: In this article, a multiscale model of gas flows is proposed for continuoustime simulation, and a reduced-order model of liquid flows is presented for reduced order simulation.
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1,285 citations

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27 Sep 2001
TL;DR: In this paper, the authors present a detailed overview of the history of the field of flow simulation for MEMS and discuss the current state-of-the-art in this field.
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TL;DR: The state-of-the-art in micropropulsion concepts and activities at the early stages in this new and exciting research area can be found in this paper, which provides a good overview of the current state of the art in this area.
Abstract: Micropropulsion is an enabling technology for microspacecraft operations by making missions possible which otherwise could not be performed For example, the formation and maintenance of platoons of microspacecraft will require a manoeuvering capability to counter orbital perturbations Microspacecraft missions involving large spacecraft resupply, repair or surveillance will also require manoeuverability The mission requirements for microspacecraft will be varied and in some cases a large range of capability might be required on the same spacecraft Micropropulsion systems must be extremely versatile to address these requirements It is clear that there is a need for micropropulsion systems from high thrust chemical engines to high specific impulse electric thrusters to fulfill specific missions just as for larger spacecraft It is becoming increasingly evident that microspacecraft will require efficient propulsion systems to enable many of the missions currently being investigated The systems constraints on mass, power, maximum voltage and volume with which microspacecraft will have to contend pose several challenges to the propulsion system designer Micropropulsion concepts that address these limitations in unique and beneficial ways, should be of interest to the microscpacecraft community Written by leading experts in the field, this new book shows the state-of-the-art in micropropulsion concepts and activities at the early stages in the development of this new and exciting research area

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Journal ArticleDOI
TL;DR: Viscous flow in supersonic de Laval nozzle, measuring gas density and rotational temperatures by electron beam techniques as discussed by the authors, was used to measure gas density in the de Lval nozzle.
Abstract: Viscous flow in supersonic de Laval nozzle, measuring gas density and rotational temperatures by electron beam techniques

134 citations