Multi-platform app-embedded model for hybrid air-breathing rocket-cycle engine in hypersonic atmospheric ascent

Tsentis, Spyros; Gkoutzamanis, Vasilis G.; Gaitanis, A.D.; Kalfas, A. I.

doi:10.1017/aer.2021.3

Cited by 5 publications

(5 citation statements)

References 20 publications

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“…While N P R increases, both the standard gross thrust and base drag increase. This results in a region where drag forces are dominant as M ∞ approaches the supersonic regime (1.1-1.2) at low to medium N P Rs (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). At M ∞ <0.8, even for low N P Rs, the GP F is positive due to the drag forces being low.…”

Section: Impact Of Cavity On the Aerodynamic Performancementioning

confidence: 99%

“…This class of engines features a heat exchanger which is incorporated to deeply cool down the incoming air prior to compression, thus extending the operational range of the downstream turbomachinery. Several concepts based on this principle have been investigated theoretically and experimentally over the years [8] and have been found to exhibit significant efficiency improvements compared to contemporary chemical rocket engines [9,10,11]. Studies on the conceptual development of propulsive architectures that are derived from the aforementioned pre-cooled concepts, but are tailored to sustainable high-speed flight rather than space access, have also been reported in the public domain [12].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Impact Of Cavity On the Aerodynamic Performancementioning

confidence: 99%

Section: Introductionmentioning

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

View full text Add to dashboard Cite

show abstract

“…While 𝑁 𝑃𝑅 increases, both the standard gross thrust and base drag increase. This results in a region where drag forces are dominant as 𝑀 ∞ approaches the supersonic regime (1.1-1.2) at low to medium 𝑁 𝑃𝑅𝑠 (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). At 𝑀 ∞ <0.8, even for low 𝑁 𝑃𝑅𝑠, the 𝐺𝑃𝐹 is positive due to the drag forces being low.…”

Section: Overall Aerodynamic Performancementioning

confidence: 99%

“…This class of engines features a heat exchanger which is incorporated to deeply cool down the incoming air prior to compression, thus extending the operational range of the downstream turbomachinery. Several concepts based on this principle have been investigated theoretically and experimentally over the years [8] and have been found to exhibit significant efficiency improvements compared to contemporary chemical rocket engines [9][10][11]. Studies on the conceptual development of propulsive architectures that are derived from the aforementioned precooled concepts, but are tailored to sustainable high-speed flight rather than space access, have also been reported in the public domain [12].…”

mentioning

confidence: 99%

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

Tsentis,

Goulos,

Prince

et al. 2023

Volume 1: Aircraft Engine

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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 yet not well understood, but are critical in terms of pressure and viscous forces. This paper presents a numerical investigation on the aerodynamic performance of a representative novel exhaust system, which employs a high-speed, truncated, ideal contoured 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 free stream 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. A decomposition of the drag domain forces exposes the major trends between the constituent elements. The impact of the cavity on the aerodynamic characteristics of the apparatus is revealed by direct comparison to an identical non-cavity configuration. Results show a consistent trend of increasing base drag with increasing NPR for all examined M∞ for both configurations. This is attributed to the jet entrainment effect and to the lower base pressure imposed by the higher jet flow expansion. The cavity region is found to have almost no impact on the incipient separation location of the nozzle flow. At low supersonic speeds of M∞ = 1.2 and high NPRs, the cavity has a significant effect on the aerodynamic performance, transitioning nozzle operation to under-expanded conditions. This results in approximately 12% higher drag coefficient compared to the non-cavity case and shifts the minimum NPR for which the system produces positive gross propulsive force to higher values.

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“…This facilitates the extended operational range of the downstream turbomachinery and thus, allows the engine to operate at higher Mach numbers, in contrast with most contemporary air-breathing systems. Several concepts based on this principle have been studied over the years [7] and have been found to exhibit signiőcantly improved efficiency, especially over chemical rocket engines in the case of space access [8,9]. While the performance advantage is well-established from a thermodynamic point of view, the aerodynamic behavior of these concepts is not yet well understood.…”

Section: Introductionmentioning

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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Multi-platform app-embedded model for hybrid air-breathing rocket-cycle engine in hypersonic atmospheric ascent

Cited by 5 publications

References 20 publications

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

Propulsion Aerodynamics for a Novel High-Speed Exhaust System

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

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