Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

Miaosheng, He; Li-zi, Qin; Liu, Yu

doi:10.1016/j.cja.2015.06.016

Cited by 22 publications

(7 citation statements)

References 49 publications

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“…In addition, flow separation may develop at the inner wall of the nozzle if the adverse pressure gradient is steep enough across the shock. The separation of the boundary layer inside the supersonic nozzle will generate a separation shock (He et al , 2015). Therefore, large wall divergence or burrs if present inside a supersonic nozzle will generate a complex flow field and its understanding and analysis is quite challenging (Mendonca and Sharif, 2010).…”

Section: Resultsmentioning

confidence: 99%

Numerical assessment of miniaturized cold spray nozzle for additive manufacturing

Nasif

Barron

Balachandar

et al. 2019

HFF

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Purpose Application of cold spray technology may exhibit significant benefits for the additive manufacturing process, particularly for producing intricate objects. To ascertain the feasibility of such an application, this paper aims to present a numerical investigation of the effect of scaling down a convergent-divergent (de Laval) nozzle, which is typically used in the cold spray industry, on the compressible flow parameters and thermal characteristics. Design/methodology/approach The Navier–Stokes equations and energy equation governing compressible flow are numerically solved using a finite volume method with a coupled solver. The conjugate heat transfer technique is used to couple fluid and solid heat transfer domains and predict the local heat transfer coefficient between the solid and fluid. The use of various RANS turbulence models has also been investigated to quantify the effect of the turbulence model on the simulation. Findings The numerical results reveal that the flow and thermal characteristics are altered as the convergent-divergent nozzle is scaled down. The static pressure and temperature profiles at any section in the nozzle are shifted toward higher values, while the Mach number profile at any section in the nozzle is shifted toward a lower Mach number. The turbulent kinetic energy at the nozzle exit increases with the scaling down of the nozzle geometry. This study also provides convincing evidence that the adiabatic approach is still suitable even though the temperature of the nozzle wall is extremely high, as required for industrial application. Results indicate that it is feasible to use the available capabilities of the cold spray technology for additive manufacturing after scaling down the nozzle. Originality/value The idea of adopting cold spray technology for additive manufacturing is new and innovative. To develop this idea into a viable commercial product, a thorough understanding of the flow physics within a cold spray nozzle is required. The simulation results discussed in this paper demonstrate the effect that scaling down of a convergent-divergent nozzle has on the flow characteristics in the nozzle.

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Section: Resultsmentioning

confidence: 99%

Numerical assessment of miniaturized cold spray nozzle for additive manufacturing

Nasif

Barron

Balachandar

et al. 2019

HFF

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“…The two-equation SST model of Menter [19] was used here to describe the turbulence. Computational results have been compared against the experimental data [20], it was shown that the SST model provides a reasonable prediction of flow separation just downstream of the shock caused by shock-boundary layer interaction inside the nozzle and, therefore, the best capture of the shock location and pressure distribution. In present study, all computations are made using the axisymmetric assumption with a primary motive of a fast and efficient means of obtaining insight into the relevant shock structure and flow separation behavior at various operating conditions.…”

Section: Computational Fluid Dynamicsmentioning

confidence: 99%

Reynolds number influence on the backpressure-induced shock–boundary layer interaction in an asymmetric supersonic expansion flow

Yuan

2019

Self Cite

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In the present study, asymmetric supersonic expansion flow produced by an annular conical supersonic nozzle has been studied under static conditions. To understand the details of Reynolds number influence on the backpressure-induced shockboundary layer interaction, a computational program has been carried out. Particular attention has been paid to the shock physics and characteristics of shock-shock and shock-boundary layer interaction change in the flow field when applied to engines operating in different ambient pressure environments. The identification of this Reynolds number correlated flow behavior changes is important for low supersonic expansion flow in engines, as it is directly attributed to the limits of off-design capability on launcher performance. The obtained results show that Reynolds number has significant influence on flow pattern at low pressure ratio, PR, conditions. When PR grows from 2.00 to 2.10, the most prominent phenomenon is that the separation point on the upper wall keeps moving downstream while the one on the lower wall keeps still. This special flow pattern results in a gradual transition from a Mach reflection to the regular reflection. However, for results at higher pressure ratios than 2.57, the comparison between the predicted shock patterns at the three ambient conditions shows a close one for these higher PR regimes. This suggests that the Reynolds number effect is going to weaken at a higher Mach number flow regime when the flow Reynolds number increases with an increase of the pressure ratio as well as the expansion flow Mach number.

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“…Watanabe et al [17] found significant side loads in LE-7A experiments, as well as the vulnerability of some experimental components to damage during nozzle startup and shutdown. Since then, an increasing number of papers have been published studying the transition of separation patterns and its effect on nozzle performance [20][21][22]. Martelli et al [21] numerically investigated a subscale parabolic overexpanded rocket nozzle and attempted to explain the hysteresis cycle between the separation patterns by analyzing the numerical solutions.…”

Section: Introductionmentioning

confidence: 99%

The Influence of External Flow Field on the Flow Separation of Overexpanded Single-Expansion Ramp Nozzle

Yu,

Mao,

et al. 2023

Aerospace

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Flow separation and transitions of separation patterns are common phenomena of nozzles working with a wide Mach range. The maximum thrust method is applied to design the single-expansion ramp nozzle (SERN) for specific operating conditions. The nozzle is used to numerically simulate the transition processes of separation patterns under the linear change in the external flow Mach number and the actual trajectory take-off condition of a rocket-based combined cycle (RBCC), to investigate the mechanism through which the external flow field influences the separation pattern transition during acceleration. The computational fluid dynamics (CFD) method is briefly introduced, followed by experimental validation. Then, the design procedure of SERN is described in detail. The simulation results indicate that as the external Mach number increases, the flow field in the nozzle undergoes transitions from RSS (ramp) to FSS, and finally exhibits a no-flow separation pattern. The rate at which the external Mach number varies has little effect on the transition principle of the nozzle flow separation patterns, but it has a significant effect on the critical Mach number of the transition points. The external flow field of the nozzle has an airflow accumulation effect during acceleration, which can delay the transition of the flow separation pattern.

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Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

Cited by 22 publications

References 49 publications

Numerical assessment of miniaturized cold spray nozzle for additive manufacturing

Numerical assessment of miniaturized cold spray nozzle for additive manufacturing

Reynolds number influence on the backpressure-induced shock–boundary layer interaction in an asymmetric supersonic expansion flow

The Influence of External Flow Field on the Flow Separation of Overexpanded Single-Expansion Ramp Nozzle

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