Restricted Shock Separation in Rocket Nozzles

Frey, Manuel; Hagemann, G.

doi:10.2514/2.5593

Cited by 147 publications

(62 citation statements)

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“…Numerical and experimental studies have been reported, for example, by Frey and Hagemann [15,24], Onofri and Nasuti [25], Pekkari [26], Schwane and Xia [27], and Shimizu et al [28]. Fundamental studies of shock-boundary layer interactions [29][30][31][32][33][34] in which (typically oblique) shocks are produced by a variety of shock generators, have, in turn, provided essential insight into the fluid dynamic features underlying shock-induced separation.…”

Section: Introductionmentioning

confidence: 99%

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

et al. 2011

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SummaryA long-standing, though ill-understood problem in rocket dynamics, rocket response to random, altitude-dependent nozzle side-loads, is investigated. Side loads arise during low altitude flight due to random, asymmetric, shock-induced separation of in-nozzle boundary layers. In this paper, stochastic evolution of the in-nozzle boundary layer separation line, an essential feature underlying side load generation, is connected to random, altitude-dependent rotational and translational rocket response via a set of simple analytical models. Separation line motion, extant on a fast boundary layer time scale, is modeled as an Ornstein-Uhlenbeck process. Pitch and yaw responses, taking place on a long, rocket dynamics time scale, are shown to likewise evolve as OU processes. Stochastic, altitude-dependent rocket translational motion follows from linear, asymptotic versions of the full nonlinear equations of motion; the model is valid in the practical limit where random pitch, yaw, and roll rates all remain small. Computed altitudedependent rotational and translational velocity and displacement statistics are compared against those obtained using recently reported high fidelity simulations [Srivastava, Tkacik, and Keanini, J. Applied Phys., 108, 044911 (2010)]; in every case, reasonable agreement is observed. As an important prelude, evidence indicating the physical consistency of the model introduced in the above article is first presented: it is shown that the study's separation line model allows direct derivation of experimentally observed side load amplitude and direction densities. Finally, it is found that the analytical models proposed in this paper allow straightforward identification of practical approaches for: i) reducing pitch/yaw response to side loads, and ii) enhancing pitch/yaw damping once side loads cease.

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Section: Introductionmentioning

confidence: 99%

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

et al. 2011

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“…Although in some circumstances this can actually increase the thrust, detrimental effects also are created, including a lateral component to the thrust vector and unsteady loads that may induce dangerous vibrations [13]. Many decades of research into this subject have yielded an increased understanding of nozzle separation physics [14][15][16][17] but it remains an active area of investigation for both rocket engines and thrusters used for attitude and roll control [18][19][20][21].…”

Section: Frs For Velocity Imaging In Aerosciences Applicationsmentioning

confidence: 99%

Filtered Rayleigh scattering diagnostic for multi-parameter thermal-fluids measurements : LDRD final report.

Beresh¹,

Grasser²,

Kearney³

et al. 2004

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Simulation-based life-cycle-engineering and the ASCI program have resulted in models of unprecedented size and fidelity. The validation of these models requires high-resolution, multiparameter diagnostics. Within the thermal/fluids disciplines, the need for detailed, high-fidelity measurements exceeds the limits of current Engineering Sciences capabilities and severely tests the state of the art; therefore, a diagnostic development effort is warranted. The focus of this LDRD is the development and application of filtered Rayleigh scattering (FRS) for highresolution, nonintrusive measurement of gas-phase velocity and temperature. This multiparameter technique adds significant experimental capability to several Sandia programs including Fire Science and Technology (FS&T) and Aerosciences programs in the Engineering Sciences Center (9100) and Reacting Flow Research at the Combustion Research Facility (8300).With FRS, the flow is laser-illuminated and Rayleigh scattering from naturally occurring sources is detected through a molecular filter. The filtered transmission may be interpreted to yield point or planar measurements of three-component velocities and/or thermodynamic state. Different experimental configurations may be employed to obtain compromises between spatial resolution, time resolution, and the quantity of simultaneously measured flow variables. This capacity for multi-parameter, non-intrusive instrumentation represents an unprecedented advance beyond presently available techniques in the Engineering Sciences Center and in the larger scientific arena. Furthermore, measurements may be made using naturally occurring scattering centers, eliminating potentially intractable difficulties associated with particulate or chemical seeding in a hypersonic or reacting environment. Molecular-filter absorption of scattered light from solid boundaries also makes FRS advantageous for detailed boundary-layer measurements. 4These advantages make FRS an attractive alternative to developed techniques and offer a substantial payoff impacting multiple thermal/fluids disciplines. Moreover, a virtually identical experimental configuration may be utilized for both aerodynamic and thermal diagnostic applications simply by adjusting the laser and molecular filter. These measurements are ideally suited for use in production-scale facilities, where many other techniques are difficult to implement.In this report, we present the results of a three-year LDRD-funded effort to develop FRS combustion thermometry and Aerosciences velocity measurement systems. The working principles and details of our FRS opto-electronic system are presented in detail. For combustion thermometry we present 2-D, spatially correlated FRS results from nonsooting premixed and diffusion flames and from a sooting premixed flame. The FRS-measured temperatures are accurate to within ±50 K (3%) in a premixed CH 4 -air flame and within ±100 K for a vortexstrained diluted CH 4 -air diffusion flame where the FRS technique is severely tested by large variation ...

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“…Later, Nasuti et al (5) , explained that an inviscid mechanism causes the generation of vortex which generates side loads. Frey et al (6) , have shown the existence of specific cap shock patterns which is a key driver for the transition from FSS to RSS and vice versa. The measurements of side loads were also conducted.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Studies of FSS-RSS Phenomena in an Over-Expanded Nozzle

Lee¹,

Kim²

2010

Journal of the Korean Society of Visualization

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Abstract. The interaction patterns between shock wave and boundary layer in a rocket nozzle are mainly classified into two categories, FSS(Free Shock Separation) and RSS(Restricted Shock Separation), both of which are associated with the thrust characteristics as well as side loads of the engine. According to the previous investigations, strong side loads of the engine are produced during the period of transition from FSS to RSS or vice versa. The present work aims at investigating the unsteady behavior of the separation shock waves in a two-dimensional supersonic nozzle, using experimental method and CFD. Schlieren optical method was employed to visualize the time-mean and time-dependent shock motions in the nozzle. The unsteady, compressible N-S equations with SST K-ω turbulence closure were solved using a fully implicit finite volume scheme. The results obtained show the separation shock motions during the transition of the interaction pattern.

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Restricted Shock Separation in Rocket Nozzles

Cited by 147 publications

References 7 publications

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

Filtered Rayleigh scattering diagnostic for multi-parameter thermal-fluids measurements : LDRD final report.

Experimental and Computational Studies of FSS-RSS Phenomena in an Over-Expanded Nozzle

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