Nozzle/afterbody integration of hypersonic vehicles by means of secondary air injection

Grönland, Tor‐Arne; Berens, Thomas M.

doi:10.2514/6.1995-6050

Cited by 7 publications

(3 citation statements)

References 6 publications

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“…However, they increase the complexity and weight of the nozzle's mechanical structure and reduce its operational reliability. Flow control techniques offer various active and passive flow control measures (Gronland and Berens 1995;Asbury et al 1996;Tsunoda et al 2000;Gamble and Haid 2004;Hao and Wang 2009;Zhou et al 2016;Zhou and Wang 2019), with secondary injection and synthetic jet actuators (SJA) being the most-used active measures. Lv et al (2017b) performed numerical simulations using a two-dimensional (2D) SERN model with cowl-based secondary injection.…”

Section: Introductionmentioning

confidence: 99%

Effect of a Secondary Injection on the Performance of Three-Dimensional Over-under TBCC Exhaust Nozzles

2023

JAFM

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A numerical simulation is used to investigate the flow field characteristics of a three-dimensional over-under turbine-based combined cycle circular-to-rectangular transition exhaust nozzle when only the turbojet flowpath is in operation. The effect on the exhaust nozzle performance of there being a secondary injection on the ramp of the expansion section of the turbojet flow path is then examined. Finally, the impact of variations in the secondary injection design parameters is further investigated. The results show that a secondary injection can improve the exhaust nozzle's performance by reducing the axial force on the inner wall of the flow path. However, changes in flight status can undermine this improvement. Under the baseline operating condition, a secondary injection with a larger angle and close to the ramp outlet can produce a more significant improvement in nozzle performance. In this study, the axial thrust coefficient, lift and pitch moment of the nozzle can be improved by a maximum of 9.312%, 66.007% and 10.975%, respectively.

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Section: Introductionmentioning

confidence: 99%

Effect of a Secondary Injection on the Performance of Three-Dimensional Over-under TBCC Exhaust Nozzles

2023

JAFM

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“…Considering the requirement for the integrated installation of the aircraft and the nozzle, the afterbody of the aircraft is typically designed as the expansion ramp of SERN. This not only helps reduce the weight of the aircraft but also provides a certain self-stabilization for the engine during off-design operations [4]. With the support of numerous experiments, the GTX scheme [5] and the ISTAR scheme [6] for RBCC were determined to achieve the thermal throat via combustion and to reach the required thrust and specific impulse using the SERN with a fixed geometric structure.…”

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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“…In order to keep high performance in a wide flight envelope, control of the internal flow separation and the separation starting position are necessary for SERN. Mechanical adjustment method (Karen and Scott, 1996;Lederer, 1996;Hao and Wang, 2009), secondary flow injection method (Grarnland and Berens, 1995;Thomas, 1995;Gronland et al, 1997), external burn method (Yungster, 1994) and air ejector (Yang, 2009) were used to improve SERN flow quality and performance under overexpanded condition, but these methods all increased the weight and the structure complexity of the exhaust system, also brought out additional cooling problems. With the development of the flow control technology, the passive flow control technique had attracted concerns of researchers to perform massive investigations due to its simple and reliable property.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the three-Dimensional Flowfield in the Single Expansion Ramp Nozzle with Passive Cavity Flow Control

Zhou¹,

Wang²

2019

JAFM

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Single Expansion Ramp Nozzle (SERN) with large expansion ratio is normally adopted for the hypersonic aircraft in consideration of integrated aircraft / propulsion system / nozzle design. Under low Mach number and low Nozzle Pressure Ratio (NPR, the ratio of inlet total pressure to outlet static pressure) conditions, the flow in the SERN is a state of severe over-expansion, the internal resistance increased obviously, the flow quality and performance of the SERN sharply deteriorated. How to effectively improve the SERN performance under over-expanded condition has become an important issue in the integrated design of hypersonic propulsion system. The passive cavity flow control technique was introduced on the upper expansion ramp of the SERN in this paper, the three-dimensional flowfield in the passive cavity SERN was investigated numerically, suitable NPR range for passive cavity flow control and impacts of passive cavity parameters were discussed. Results show the SERN performance is effectively improved when the passive cavity is applied from NPR of 5 to 10. Compared with the baseline SERN, 3.13 % improvement can be achieved for the thrust coefficient of the passive cavity SERN when NPR is 5. The passive cavity has the capacity of regulating the induced shock intensity or restraining flow separation, the reason for the change in its function is decided by the relative position between the induced shock and the passive cavity position on the upper expansion ramp of the SERN. As for each function of the passive cavity, an optimum position for the passive cavity structure exists on the upper expansion ramp. Among the primary geometric parameters of the passive cavity structure, percent of porosity is a crucial factor to affect the SERN performance by adjusting separation zone size and its separation starting position, and the improvement effectiveness of the axial thrust coefficient drops with the decrease of percent of porosity. The cavity depth and the aperture size are not sensitive to the performance of passive cavity SERN as compared to the effect of the percent of porosity.

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Nozzle/afterbody integration of hypersonic vehicles by means of secondary air injection

Cited by 7 publications

References 6 publications

Effect of a Secondary Injection on the Performance of Three-Dimensional Over-under TBCC Exhaust Nozzles

Effect of a Secondary Injection on the Performance of Three-Dimensional Over-under TBCC Exhaust Nozzles

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

Numerical Investigation on the three-Dimensional Flowfield in the Single Expansion Ramp Nozzle with Passive Cavity Flow Control

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