Side Loads in Dual Bell Nozzles, Part I: Phenomenology

Stark, Ralf; Nürnberger-Génin, Chloé

doi:10.2514/6.2010-6729

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…Several experimental, cold gas and hot fire studies and numerical simulations have been carried out to study the TICCP configuration in its two operating modes and the transition between them Stark 2007, 2009). Several effects have been analyzed, such as the effect of the divergence angle of the extension (Stark and Génin 2010;Verma et al 2011), the effect of the density of the cold gases (Verma et al 2010), and the effect of the injection of gas at the level of the inflection point on the transition. Due to the effects of viscosity inside the boundary layer, the pressure follows a negative slope and not a discontinuity as predicted by theory.…”

Section: Introductionmentioning

confidence: 99%

“…This was described by Martelli et al (2006). The extension must then be divided into the inflection region, where the pressure gradient is negative, and the rest section, where the wall pressure is constant (Stark and Génin 2010). In the same study, Stark and Génin have noticed that before the transition, where the flow quickly recollects on the whole extension, the wall pressure drops in the inflexion region and the point of detachment moves downstream of the inflexion.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Investigation of Supersonic Flows on Innovative Nozzles (Dual Bell Nozzle)

2023

JAFM

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The Dual Bell Nozzle is the most ambitious of several supersonic, altitude-compensating nozzle concepts for rocket engines. This design's objective is to enhance performance in two different evolving regimes (Sea-Level and High Altitude Mode) by self-adaptation with no mechanical control. The concept is simple in theory, but the structural efforts involved are significant. The study carried out in this paper is a simulation of the flows in this type of nozzle. Computational fluid dynamics (CFD) is increasingly used as an analytical tool in research and industry. Simulation is not a substitute for experimentation but a complement to it; it allows the analysis of the problem in real conditions (reproduce tests that are done in experimentation to better understand them and at lower cost) or, on the contrary, in extreme or marginal test conditions (extreme climates, installation defects, etc.). Through simulation, the studied system becomes more flexible. We can easily make parametric studies. Simulation almost always takes the form of a program or computer tool. These are commonly called simulation environments. Developments and progress over the past two decades have led to the emergence of a methodology that has become standard. As for any complex system, the control of a phenomenon is based on the identification and modularization of the tasks. Currently, the standard methodology divides the simulation process into four distinct tasks: geometric modeling, meshing, solving, and finally analysis and visualization. In this study, we will present a test case used to validate our computational models that will be used to optimize the profile of a dual bell nozzle. We will use the Ansys-ICEM environment to generate the meshes and the Ansys-Fluent environment to solve the equations of our models. Our results will then be compared with experimental and numerical data from our literature review.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Supersonic Flows on Innovative Nozzles (Dual Bell Nozzle)

2023

JAFM

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“…18. Result of side load measurements [20] 한 기하학적 변수들의 영향을 조사하기 위해 질 소를 사용한 냉가스 실험을 진행하였다 [25]. 실험 에 사용된 노즐과 실험 장치를 Fig.…”

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“…를 90도 간격으로 튜브 벽에 위치시키고 실험 동 안 발생하는 횡력에 의해 발생하는 변형을 측정 한다 [25]. Figure 17은 일반적으로 사용되는 벨 노즐과 듀얼 벨 노즐의 측하중 비교 실험의 결과이다 [25] 열화상을 이용하여 온도를 측정한 결과, 해수 면 조건에서는 변곡점을 전후로 온도가 급격하게 변하였고, 고고도에서는 변곡점을 지난 후 점차 소하는 것을 확인하였다 (Fig. 19) …”

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Characteristics and Key Parameters of Dual Bell Nozzles of the DLR, Germany

Kim

Huh²

2015

Journal of the Korean Society for Aeronautical & Space Scie

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Various types of altitude compensation nozzles have been investigated to develop an effective propulsion system. In order to obtain baseline data for future study of dual bell nozzles, main characteristics and key parameters of dual bell nozzles are summarized and described by analysing DLR dual bell nozzles. DLR's experimental researches show that inflection angle is proportional to transition NPR, and extension length is proportional to side load, but inversely proportional to transition NPR and transition duration. Therefore, the nozzle geometry can be determined through the performance prediction process and thus the optimization process is required to meet performance requirements between parameters.

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