Viscous Effects on Performance of Two-Dimensional Supersonic Linear Micronozzles

Louisos, William; Hitt, Darren L.

doi:10.2514/1.33434

Cited by 44 publications

(13 citation statements)

References 11 publications

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“…If it is too low, the viscous flow at the end walls can decrease propellant speed as it exhausts. Similar issues can arise when conventional ideal Bell nozzles are used at this scale [42], and have often been replaced by conical nozzles. Surface roughness also affects the performance of microthrusters using cold gas more than larger thrusters.…”

Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 84%

“…Simulations of such thrusters have shown discharge coefficients between 0.8 and 0.85 for Reynolds numbers of around 300, up to more than 0.9 for Re 1200 [20]. It was also demonstrated that end-wall effects are very important in 3D or linear nozzles [20,42,52,55]. The aspect ratio of a 3D nozzle is the ratio between the nozzle length and throat width.…”

Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 99%

“…A significant body of research has shown that micronozzles for transonic flows do not follow closely to the isentropic relations applicable to their larger counterparts [37][38][39][40][41][42]. This is due to the low Reynolds numbers inherent to low-thrust rockets that use gaseous expansion; viscous losses can reduce thrust efficiency dramatically and in some cases prevent the flow from becoming supersonic [38,39].…”

Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 99%

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Bimodal Propulsion System for Small Spacecraft: Design, Fabrication, and Performance Characterization

Little

Jugroot

2020

Journal of Spacecraft and Rockets

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The use of multimodal space propulsion has the benefit of increasing satellite mission flexibility with the ultimate goal of decreasing mission development costs. The present paper explores the development of a dual-mode thruster for small spacecraft. By combining an electrospray within the confines of a cold gas nozzle, the fabricated and tested propulsive device can operate either in a high thrust or high specific impulse mode. The thruster herein makes use of a laser microfabricated porous glass triangular prism electrospray emitter using passively fed ionic liquid (EMI-BF 4 ) as propellant. The electrospray performance has been indirectly quantified with beam current measurements on the order of 200 nA at an extraction voltage of 2.5 kV, which correlates to a significantly lower thrust than expected. For the second thrust mode, cold gas thrust and specific impulse were measured directly to be 7.9 mN and 44 s, respectively, using nitrogen propellant. The operation of this device in both modes has exemplified its potential applicability to microspacecraft while demonstrating the tradeoffs of bimodal thruster design.

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Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 84%

Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 99%

Section: B Cold Gas Linear Nozzle: Selection Of Key Parametersmentioning

confidence: 99%

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Bimodal Propulsion System for Small Spacecraft: Design, Fabrication, and Performance Characterization

Little

Jugroot

2020

Journal of Spacecraft and Rockets

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“…As evidence for this, an obvious geometrical mismatch between the vinyl layer and adhesive layer was spotted in the figure . The defects have both pros and cons. During the operation of microthruster, subsonic viscous boundary layers form as the flowing gas interacts with the micronozzle sidewalls [20,21]. The layers tend to grow and expand toward the center of micronozzle, retarding the flow and consequently reducing the efficiency of the system.…”

Section: Surface Contour Of Patterned Green Layersmentioning

confidence: 99%

Fabrication of a zirconia MEMS-based microthruster by gel casting on PDMS soft molds

Cheah

Khiew

Chin

2012

J. Micromech. Microeng.

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A zirconia microelectromechanical-system-based microthruster was fabricated through a newly developed fabrication route. Gel casting of homogenously dispersed zirconia suspension on polydimethylsiloxane soft mold was utilized to replicate the geometries of microthruster design onto a ceramic layer of about 1.2 mm thick. Lamination of the patterned ceramic layer to another flat ceramic layer and subsequent sintering produced the microthruster. Characterizations on the fabricated prototype showed good shape retention on the replicated geometries and good quality of lamination. Shrinkage of about 10-15% was noted after sintering. The current fabrication route is particularly promising for the development of high-performance micropropulsion systems which require their structural material to survive in an extreme environment which is corrosive, of high temperature and highly oxidative.

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“…In addition to the real gas effects, viscous effects may also be critical in some cases, especially for micro-nozzles (Louisos & Hitt 2012) or nozzles manufactured by alternative production methods (e.g. additive manufacturing) due to their inherent high surface roughness, leading to higher friction factors and consequently nozzle flow deviation from the isentropic behaviour.…”

Section: Introductionmentioning

confidence: 99%

Viscous effects on real gases in quasi-one-dimensional supersonic convergent divergent nozzle flows

Restrepo

Simões-Moreira²

2022

J. Fluid Mech.

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Viscous effects on an ideal gas flow in a supersonic convergent–divergent nozzle are a well-studied subject in classical gas dynamics. However, the ideal assumption fails on fluids that exhibit complex behaviours such as near-critical-region and non-ideal dense vapours. Under those conditions, a realistic equation of state (EOS) plays a vital role for a precise and realistic computation. This work examines the problem for solving the quasi-one-dimensional viscous compressible flow using a realistic EOS. The governing equations are discretised and solved using the fourth-order Runge–Kutta method coupled with a state-of-the-art EOS to calculate the thermodynamic properties. The role of the Grüneisen parameter along with viscous and real gas effects and their influence on the sonic point formation are discussed. The study shows that the flow may not achieve the supersonic regime for any pressure ratio depending on the combination of that parameter and the normalised friction factor. In addition, the analysis yields the discharge coefficient and the isentropic nozzle efficiency, which may achieve maximum values as a function of the stagnation conditions. Finally, the study also evaluates the formation and intensity of normal shock waves by using the Rankine–Hugoniot relations, which now depend on the real gas and viscous effects in opposition to the inviscid solution. Moreover, the methodology used captures the sonic point and shock wave position by a space marching algorithm using the Brent method for scalar minimisation. Experimental data available in the open literature corroborate the approach.

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Viscous Effects on Performance of Two-Dimensional Supersonic Linear Micronozzles

Cited by 44 publications

References 11 publications

Bimodal Propulsion System for Small Spacecraft: Design, Fabrication, and Performance Characterization

Bimodal Propulsion System for Small Spacecraft: Design, Fabrication, and Performance Characterization

Fabrication of a zirconia MEMS-based microthruster by gel casting on PDMS soft molds

Viscous effects on real gases in quasi-one-dimensional supersonic convergent divergent nozzle flows

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