Plug Nozzle Flowfield Analysis

Rommel, Tobias; Hagemann, G.; Schley, C.-A.; Krülle, G.; Manski, D.

doi:10.2514/2.5227

Cited by 60 publications

(15 citation statements)

References 1 publication

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“…[10][11][12][13][14][15][16] The details of complex flow fields has not completely ascertained yet. It is particularly important to characterize the influence of clustering effects [13][14][15][16] and external conditions. The more details need to be grasped in order to optimize this nozzle's design.…”

Section: Introductionmentioning

confidence: 99%

Three dimensional numerical investigation of the clustered linear aerospike nozzle’s flow affected by changing the distance between neighboring cell nozzles

Miyazawa

Matsuo

Takahashi

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Aerodynamic performance of the simplified test models of infinite consequence clustered linear aerospike nozzles was numerically investigated and results were compared with those of an experimental study. The model of numerical target is focused on predicting the ramp pressure distribution and the effect of interval of the neighboring clustered cell nozzles, where jet exhaust flow emits 3.5 in Mach number. Its thrust performances were examined in terms of two types of the cell nozzle interval, 4 and 17 mm, whose model is named half4c and half3c respectively. Clustered cell nozzles connect with a straight ramp, and another end of the straight ramp connects with a 12-degree-inclined slope ramp. The ramp consists of a pair of these ramps. External main flow in Mach 2.0 impinges on the N 2 cell nozzle jets and ramp surface. On the ramp surface, pressure distribution illustrated clear cell pattern resulting from three-dimensional bumpy oblique shock wave generated above slope ramp. NDP (Normalized Difference Pressure) at ramp of CFD was compared with that of experiment. It showed quantitative agreement within 10% difference. NDP distribution at jet center of span wise cross-section showed opposite phase differences from that at base center. Flow features from streamline showed the presence of vertical vortex and the deflection of main flow and jet flow. Streamline not only showed how to mix between these flows but also suggested that oblique shock wave generated at front half of a slope ramp was bumpy as shown in the great deflection of stream. At half4c model, main flow did not sink to near the ramp wall except in the case of over-expansion, while at half3c model a part of main flow was mixed with jet flow at jet center only in the case of over-expansion. Thus flow features could be classified by whether expansion form is over-expansion in both cell nozzle intervals. The ramp pressure distribution reflects to pressure thrust. Consider the situation that straight ramp angle against the virtual airframe axis plane can be changed. At this time, the airframe angle of making thrust maximum tended to decrease with increase in NPR and with becoming shorter in cell nozzle interval. NomenclatureA w = ramp wall surface area, mm 2 A r = cell nozzle cross-section area, mm 2 V r = jet exhaust velocity, m/s M a = freestream (external main flow) Mach number M r = cell nozzle jet exhaust Mach number NDP = Normalized difference pressure defined as (P-P b )/P 0r NPR = Nozzle Pressure Ratio defined as P 0r /P b P a = freestream (external main flow) static pressure, kPa P b = static pressure in the test chamber, kPa P r = jet Mach number at cell nozzle exit, kPa P w = ramp pressure, kPa P 0a = total pressure of freestream (main flow), kPa P 0r = chamber pressure of cell nozzle jet flow, kPa x = coordinate in stream wise direction, mm y = coordinate in transverse direction, mm z = coordinate in span wise direction, mm θ = airframe angle, which is straight ramp angle against the virtual airframe axis plane, deg. θ max = optimum airframe a...

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Section: Introductionmentioning

confidence: 99%

Three dimensional numerical investigation of the clustered linear aerospike nozzle’s flow affected by changing the distance between neighboring cell nozzles

Miyazawa

Matsuo

Takahashi

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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“…Based on the above background, different types of nozzle concept with altitude-adapting capabilities have been developed and tested on the ground in the past, and the aerospike nozzle is included as a strong contender for the propulsion system of reusable spacecraft. 1,2 In the recent years, a renewed interest in the aerospike nozzle flowfield has been generated for both rocket and aeronautic applications. [2][3][4][5][6] However, while flow separation in over-expanded planar or bell ideal and optimized contour nozzles has been widely investigated to elucidate the phenomenon of boundary layer separation and shock interactions, aerospike nozzles have received little attention in the frame of this study.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 In the recent years, a renewed interest in the aerospike nozzle flowfield has been generated for both rocket and aeronautic applications. [2][3][4][5][6] However, while flow separation in over-expanded planar or bell ideal and optimized contour nozzles has been widely investigated to elucidate the phenomenon of boundary layer separation and shock interactions, aerospike nozzles have received little attention in the frame of this study. Verma 4 and Kapilavai et al 7 presented pioneering work upon flow separation behavior in aerospike nozzles that operated at NPRs below 10, and both of the two studies indicated that the presence of flow phenomenon was associated with nozzle flow separation, and unsteady shock oscillation induced by the interaction of the shock/boundary layer seen in conventional supersonic nozzles with diverging sections could also be expected in aerospike nozzles at off-design operating NPRs.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

Miaosheng

Li-zi

Liu

2015

Chinese Journal of Aeronautics

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A three-part numerical investigation has been conducted in order to identify the flow separation behavior--the progression of the shock structure, the flow separation pattern with an increase in the nozzle pressure ratio (NPR), the prediction of the separation data on the nozzle wall, and the influence of the gas density effect on the flow separation behavior are included. The computational results reveal that the annular conical aerospike nozzle is dominated by shock/shock and shock/boundary layer interactions at all calculated NPRs, and the shock physics and associated flow separation behavior are quite complex. An abnormal flow separation behavior as well as a transition process from no flow separation at highly over-expanded conditions to a restricted shock separation and finally to a free shock separation even at the deign condition can be observed. The complex shock physics has further influence on the separation data on both the spike and cowl walls, and separation criteria suggested by literatures developed from separation data in conical or bell-type rocket nozzles fail at the prediction of flow separation behavior in the present asymmetric supersonic nozzle. Correlation of flow separation with the gas density is distinct for highly overexpanded conditions. Decreasing the gas density or reducing mass flow results in a smaller adverse pressure gradient across the separation shock or a weaker shock system, and this is strongly coupled with the flow separation behavior. The computational results agree well with the experimental data in both shock physics and static wall pressure distribution at the specific NPRs, indicating that the computational methodology here is advisable to accurately predict the flow physics.

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“…Introduction P LUG nozzles have been extensively studied experimentally and analytically since the 1950s [1][2][3]. In the recent past, a renewed interest in plug nozzle flowfields has been generated for both rocket as well as aeronautic [4][5][6][7][8][9] applications. The generic character of an axisymmetric plug nozzle is shown in Fig.…”

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confidence: 99%

Experimental Testing and Numerical Simulations of Shrouded Plug-Nozzle Flowfields

Kapilavai¹,

Tapee²,

Sullivan³

et al. 2012

Journal of Propulsion and Power

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The static tests of an experimental, point-design, shrouded plug nozzle are the focus of current experimental and computational efforts. Unlike a conventional plug nozzle, the presence of a shroud results in converging-diverging nozzlelike behavior at off-design nozzle pressure ratios and a return to conventional plug nozzlelike behavior at design conditions. The static experimental tests brought to light unsteady characteristics related to shock/shock and shock/boundary-layer interactions at off-design and steady-operational characteristics at design conditions. Through a series of axisymmetric computations, the flow structure, unsteady characteristics, and static pressure distributions are analyzed in conjunction with the experiments. The computational results are in good agreement with experimental observations and are found to be a fast, efficient way of understanding the experimental data and, thereby, the nature of shrouded, plug-nozzle flowfields.

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Plug Nozzle Flowfield Analysis

Cited by 60 publications

References 1 publication

Three dimensional numerical investigation of the clustered linear aerospike nozzle’s flow affected by changing the distance between neighboring cell nozzles

Three dimensional numerical investigation of the clustered linear aerospike nozzle’s flow affected by changing the distance between neighboring cell nozzles

Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

Experimental Testing and Numerical Simulations of Shrouded Plug-Nozzle Flowfields

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