Experimental and numerical analysis of a two-duct nozzle/afterbody model at supersonic Mach numbers

Berens, Thomas M.

doi:10.2514/6.1995-6085

Cited by 4 publications

(2 citation statements)

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“…References [13,14] indicated that better performance was achieved by separating the overexpanded nozzle exhaust flow from the SERN ramp with oblique shocks generated through fluidic injection from the trailing edge of the SERN cowl and the ramp of the SERN. A similar method also had been used to improve the SERN's off-design performance in the S€ anger Space Transportation System [15,16], the numerical and test results indicated that the gross thrust vector can be adjusted to the requirements of the inlet forces and external aerodynamics and high thrust efficiency in flight direction can be achieved with the injection of secondary air into the nozzle flow [17]. Reference [18] focused on an over-under installation concept and discussed various propulsion/airframe design, integration, performance, and operability considerations.…”

Section: Introductionmentioning

confidence: 99%

Design and Experimental Study of an Over-Under TBCC Exhaust System

Mo¹,

Xu²,

Zhang

2013

Journal of Engineering for Gas Turbines and Power

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Turbine-based combined-cycle (TBCC) propulsion systems have been a topic of research as a means for more efficient flight at supersonic and hypersonic speeds. The present study focuses on the fundamental physics of the complex flow in the TBCC exhaust system during the transition mode as the turbine exhaust is shut off and the ramjet exhaust is increased. A TBCC exhaust system was designed using methods of characteristics (MOC) and subjected to experimental and computational study. The main objectives of the study were: (1) to identify the interactions between the two exhaust jet streams during the transition mode phase and their effects on the whole flow-field structure; (2) to determine and verify the aerodynamic performance of the over-under TBCC exhaust nozzle; and (3) to validate the simulation ability of the computational fluid dynamics (CFD) software according to the experimental conditions. Static pressure taps and Schlieren apparatus were employed to obtain the wall pressure distributions and flow-field structures. Steady-state tests were performed with the ramjet nozzle cowl at six different positions at which the turbine flow path were half closed and fully opened, respectively. Methods of CFD were used to simulate the exhaust flow and they complemented the experimental study by providing greater insight into the details of the flow field and a means of verifying the experimental results. Results indicated that the flow structure was complicated because the two exhaust jet streams interacted with each other during the exhaust system mode transition. The exhaust system thrust coefficient varied from 0.9288 to 0.9657 during the process. The CFD simulation results agree well with the experimental data, which demonstrated that the CFD methods were effective in evaluating the aerodynamic performance of the TBCC exhaust system during the mode transition.

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Section: Introductionmentioning

confidence: 99%

Design and Experimental Study of an Over-Under TBCC Exhaust System

Mo¹,

Xu²,

Zhang

2013

Journal of Engineering for Gas Turbines and Power

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“…the engine and afterbody exhausts) of nozzle are very complex, so nozzle designs based on inviscid flow theory are generally only regarded as preliminary [4]. In recent years, with the development of computational fluid dynamics (CFD), high credibility numerical simulation has become the main analytical tool for performance evaluation [5][6][7], design [8,9] and particularly optimization [2,[10][11][12][13][14][15] …”

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confidence: 99%

Aerodynamic optimization and evaluation for the three-dimensional afterbody/nozzle integrated configuration of hypersonic vehicles

et al. 2012

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The optimization of 2D expansion lines and key parameters of three-dimensional configurations was carried out under simulated conditions of Mach 6.5 and a flight altitude of 25 km for an integrated configuration of the afterbody/nozzle of a hypersonic vehicle. First, the cubic B-spline method was applied to parameterize the expansion lines of the upper expansion ramp. The optimization procedure was established based on computational fluid dynamics and the sequential quadratic programming method. The local mesh reconstruction technique was applied to improve computational efficiency. A three-dimensional integrated configuration afterbody/nozzle was designed based on the two-dimensional optimized expansion lines. The influence rules incorporated certain key design parameters affecting the lift and thrust performance of the configuration, such as the ratio of the lengths of the lower expansion ramp to the afterbody (l/L), the dip angle of the lower expansion ramp ω, and the ratio of exit height to the length of afterbody (H/L). Under these conditions, we found that the integrated configuration has optimal performance when l/L=1/6, H/L=0.35 and   =10°. We also showed that the presence of a side-board promotes lift and thrust performance, and effectively prevents the leakage of high pressure gas. For scramjet-powered hypersonic vehicles, an integrated configuration body/engine design is usually adopted. The wave rider or lift body configuration is used as the fore body. Therefore the fore body of hypersonic vehicle provides most of the lift and also forms the pre-compression face of the engine inlet. The afterbody of the vehicle can be considered as an extension to the nozzle, providing lift and thrust. With this design, the bottom surface of the airframe is fully integrated with the propulsion system, and therefore drag force can be reduced. As a result, the afterbody of vehicle is designed as an integrated structure with the engine nozzle. The afterbody is the major thrust producing component, providing more than 50% of the total engine thrust [1,2].The single expansion ramp nozzle is a typical propulsion system design. For a given Mach number, attack angle and dynamic pressure, the airflow expansion and the aerodynamic performance of afterbody mainly depend on its geometry, especially the upper expansion line. Early methods of nozzle design adopted the characteristic and the variational method to achieve the maximum lift-drag ratio or minimum length of nozzle based on inviscid flow theory (typically Rao's method) [3,4]. The flow phenomena in the entry (i.e. the engine and afterbody exhausts) of nozzle are very complex, so nozzle designs based on inviscid flow theory are generally only regarded as preliminary [4]. In recent years, with the development of computational fluid dynamics (CFD), high credibility numerical simulation has become the main analytical tool for performance evaluation [5][6][7], design [8,9] and particularly optimization [2,[10][11][12][13][14][15]

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Flowfield and Performance Analysis of a Three-Dimensional TBCC Exhaust Nozzle

Wang

et al. 2017

Journal of Engineering for Gas Turbines and Power

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Compared to other engines, turbine-based combined cycle (TBCC) engine is one of the most suitable propulsion systems for hypersonic vehicle. Because of its fine reusability, wide flight envelope, and safety margins, TBCC engine is becoming a more and more important hotspot of research. In this paper, a three-dimensional (3D) over–under TBCC exhaust system is designed, simulated, and the results are discussed, wherein the ramjet flowpath is designed by the quasi-two-dimensional method of characteristics (MOC). A new scheme of rotating around the rear shaft is proposed to regulate the throat area of turbine flowpath. Cold flow experiments are conducted to gain a thorough and fundamental understanding of TBCC exhaust system at on and off-design conditions. To characterize the flow regimes, static pressure taps and schlieren apparatus are employed to obtain the wall pressure distributions and flowfield structures during the experiments. Detailed flow features, as well as the thrust performance, are simulated by the computational fluid dynamics (CFD) method. Both the numerical and experimental results show that the TBCC exhaust nozzle in this study can provide sufficient thrust during the whole flight envelop despite a little deterioration at the beginning of the mode transition. The research provides a new and effective scheme for the exhaust system of TBCC engine.

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Experimental and numerical analysis of a two-duct nozzle/afterbody model at supersonic Mach numbers

Cited by 4 publications

References 0 publications

Design and Experimental Study of an Over-Under TBCC Exhaust System

Design and Experimental Study of an Over-Under TBCC Exhaust System

Aerodynamic optimization and evaluation for the three-dimensional afterbody/nozzle integrated configuration of hypersonic vehicles

Flowfield and Performance Analysis of a Three-Dimensional TBCC Exhaust Nozzle

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