Investigation of the base flow of a generic space launcher with dual-bell nozzle

Scharnowski, Sven; Kähler, Christian J.

doi:10.1007/s12567-020-00333-5

Cited by 3 publications

(4 citation statements)

References 53 publications

(77 reference statements)

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“…As the shape of fairing is axisymmetric, a 2D model with triangle mesh was used for better calculation efficiency as the calculation accuracy was also ensured [7][8]. The diameter of the fairing are all 20 cm, and 20 cm length was set as a standard L. From 0.25 L to 2 L, use 0.25 L as a width step, eight groups of fairings were studied.…”

Section: Methodsmentioning

confidence: 99%

Research on fairings with different aspect ratio under subsonic flow Based On FLUENT

Hu¹

2022

HSET

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When rocket flying at high speed, large air resistance will generate at the front and around the rocket fairing. Results in significant reduction of the rocket's range and speed. The research shows that the air resistance produced by the fairing accounts for more than half of the total resistance of the rocket. As the shape of fairing is axisymmetric, a 2D model with triangle mesh was used for simulation to analyze the pressure around fairing. Eight group of fairing with aspect ratio from 0.25 to 2 were studied under the compressible non viscous airflow with 200 m/s incoming speed. The air resistance decreases with the increase of the aspect ratio, and the high pressure area around the fairing also reduces from more than a half to one third of the total fairing length. In these eight groups of fairings, the fairing with aspect ratio 2 performs best, receives the minimum air resistance and with pressure mainly distributed at the front end of the fairing.

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Section: Methodsmentioning

confidence: 99%

Research on fairings with different aspect ratio under subsonic flow Based On FLUENT

Hu¹

2022

HSET

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“…Most of the research effort in the public domain is focused on axisymmetric conőgurations incorporating blunt-based bodies [10ś12] and backward facing steps (BFS) [13,14], owing to the axisymmetric topology usually found in space launchers. However, studies on planar, powered-on conőgurations featuring a dual-bell nozzle at the base can also be found [15].…”

Section: B Base Flow Characteristicsmentioning

confidence: 99%

Wind Tunnel Installation Effects on the Base Flow for a High-Speed Exhaust System

Tsentis,

Goulos,

Prince

et al. 2024

AIAA SCITECH 2024 Forum

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It is envisaged that future propulsion concepts will enable high-speed flight and improve space access. However, their aerodynamic behavior is not yet well understood, especially at the base where severe flow separation occurs, requiring further analyses using both numerical and experimental techniques. This paper presents a numerical investigation of the wind tunnel installation effects on a representative, sub-scale, high-speed exhaust system. The analysis facilitates an ongoing design of experiments and de-risking activity. The apparatus features a truncated, ideal-contoured nozzle and an axially symmetric cavity region embedded at the base. The viable design space owing to high blockage is identified in terms of maximum approach Mach number. A systematic jet vectoring effect is observed in all cases examined. The origins of this effect are investigated and attributed solely to the pressure distribution asymmetry caused by the existence of the wing-pylon. Additionally, local flow similarity at the base of the tunnel-installed model with respect to unconstrained flow is investigated and presented, along with a proposed methodology to establish comparability. This analysis is of increased practical importance, due to the size range of most closed transonic tunnels found in academic research facilities. Results show that the pressure distribution at pre-choking tunnel conditions agrees within less than 1.5% and 0.1% for the base and cavity wall surfaces, respectively. At post-choking tunnel operation, the base pressure distribution of the model exhibits increased deviations in the azimuthal direction of up to 7.5%. The base pressure distribution in the corresponding unconstrained flow case falls within the observed pressure range of the tunnel-installed model, while the pressure distribution along the cavity wall agrees within less 1%. The findings of this study suggest that a jet vectoring effect could potentially manifest to wingtip mounted nacelles, usually incorporated in future, high-speed vehicles. Finally, it is demonstrated, that local flow similarity exists at the base with respect to unbounded flow, even for post-choking tunnel conditions, which is critical in base flows and base drag reduction analyses.

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“…Salient flow-field characteristics near the base and wake regions have been extensively studied in the past for generic propulsive configurations, including both planar [25] and axisymmetric ones. Most of the studies found for axisymmetric configurations deal with blunt-based bodies [26,27,28] and backward facing steps (BFS) [29,30], often for power-off conditions [26,27,28,31].…”

Section: Base Flow Characteristicsmentioning

confidence: 99%

“…Most of the studies found for axisymmetric configurations deal with blunt-based bodies [26,27,28] and backward facing steps (BFS) [29,30], often for power-off conditions [26,27,28,31]. However, the effect of a propulsive jet on the base pressure and near-wake characteristics has also been investigated in power-on configurations [25,29,30]. Saile et al [32,33] examined the impact of the nozzle length extending from the base for a generic space launcher configuration, using an axisymmetric BFS geometry with a propulsive jet.…”

Section: Base Flow Characteristicsmentioning

confidence: 99%

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

Tsentis,

Goulos,

Prince

et al. 2023

Journal of Engineering for Gas Turbines and Power

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A key requirement to achieve sustainable high-speed flight and efficiency improvements in space access lies in the advanced performance of future propulsive architectures. Such concepts often feature high-speed nozzles, similar to rocket engines, but employ different configurations tailored to their mission. Additionally, they exhibit complex interaction phenomena between high-speed and separated flow regions at the base, which are not yet well understood. This paper presents a numerical investigation on the aerodynamic performance of a representative, novel exhaust system, which employs a high-speed nozzle and a complex-shaped cavity region at the base. Reynolds-Averaged Navier–Stokes computations are performed for a number of nozzle pressure ratios (NPRs) and freestream Mach numbers in the range of 2.7 < NPR < 24 and 0.7 < M∞ < 1.2, respectively. The corresponding Reynolds number lies within the range of 1.06 × 106 < Red < 1.28 × 106 based on the maximum diameter of the configuration. The impact of the cavity is revealed by direct comparison to an identical noncavity configuration. Results show a consistent trend of increasing base drag with increasing NPR for both configurations, owing to the jet entrainment effect. Cavity is found to have no impact on the incipient separation location of the nozzle flow. At conditions of M∞ = 1.2 and high NPRs, the cavity has a significant effect on the aerodynamic performance, transitioning nozzle operation to underexpanded conditions. This results in approximately 12% higher drag coefficient compared to the noncavity case and shifts the minimum NPR required for positive gross propulsive force to higher values.

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Investigation of the base flow of a generic space launcher with dual-bell nozzle

Cited by 3 publications

References 53 publications

Research on fairings with different aspect ratio under subsonic flow Based On FLUENT

Research on fairings with different aspect ratio under subsonic flow Based On FLUENT

Wind Tunnel Installation Effects on the Base Flow for a High-Speed Exhaust System

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

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