Effect of Geometry on Exit Temperature from Serpentine Exhaust Nozzles

Crowe, Darrell S.; Martin, Christopher L.

doi:10.2514/6.2015-1670

Cited by 14 publications

(9 citation statements)

References 22 publications

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“…According to the energy equation of ideal and adiabatic fluid, the relationship between the local sound velocity and the critical sound velocity is (11) Dividing equation ( 11) by c * and omitting the small quantities above second-order, the following perturbation velocity potential equation can be obtained, which is suitable for the region near the sonic line of the curved section…”

Section: Distribution Of Sonic Linementioning

confidence: 99%

“…The further computational studies by Harloff 9,10 showed that the condition of irrotational and inviscid flow would not lead to the secondary flow. Flow features of convergent–divergent S-nozzles were computed by Crowe, 11,12 and results displayed that the local supersonic regions were induced near two turns. The transverse flow was induced because of the change of cross-section and curvature of the S-nozzle.…”

Section: Introductionmentioning

confidence: 99%

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Influences of key parameters on flow features in the curved ducts with equal area

Sun

2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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Curved ducts are widely used in aircraft engines to improve some capability of aero-engines. Complex internal flow characteristics would be induced by the curvature in such components. In this study, the influence of parameters, including the arc angle α, the curvature radius R i, and the height H, on the local accelerating and transonic flow in the curved ducts with equal area were studied numerically and theoretically under different nozzle pressure ratios (NPRs). The range of the Re number based on the height of the duct and the velocity at the inlet was [Formula: see text] ∼ [Formula: see text]. The shear stress transport κ-ω turbulent model was proved by the test data to suitably simulate the flow field in curved ducts because it could accurately predict the flow separations under adverse pressure gradients. The uncertainty of the pressure scan value to obtain the test data was ±0.05%. Numerical results showed that the effect of α on the flow characteristics of the curved ducts is little. The maximum Ma number in the curved section reduces with the increase of R i, and that grows with the increase of H. The range of the maximum Ma number was 1.20∼1.80. The critical NPRs, which decided the special flow features, were found in the curved ducts. The critical NPR rises with the increase of R i; however, the effect of H on the critical NPR is irregular due to the flow separations located near the lower wall induced by the large adverse pressure gradient. The theoretical results based on the small perturbation theory of transonic flow in the polar coordinate system proved that the distribution of sonic line was just dependent on the inner diameter R1, the outer diameter R2, and the arc angle θmax of the curved section. The critical mass flow and the critical NPR2 are only related to R1 and R2.

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Section: Distribution Of Sonic Linementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influences of key parameters on flow features in the curved ducts with equal area

Sun

2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Low observable serpentine nozzle is one of the key technologies to improve the stealth performance of the exhaust system of aero-engine. Along with the long-term high-speed flight of the aircraft, the serpentine nozzle will continue to work under the multi-physical field load environment composed of aerodynamic load, thermal load and structural load [1,2]. The geometric configuration of the serpentine nozzle is more complex than that of the traditional axisymmetric nozzle.…”

Section: Introductionmentioning

confidence: 99%

Investigation on influence mechanism of length-to-diameter ratio on fluid-structure interaction characteristic of serpentine nozzle

Li,

Zhou,

Shi

et al. 2024

J. Phys.: Conf. Ser.

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The effect of different length-to-diameter ratios on the fluid-structure coupling characteristics of double serpentine nozzle for turbofan engine was studied by using serial bidirectional loose coupling method. The results show that the structural deformation of the serpentine nozzle is mainly located at the downstream channel of the first bend of the nozzle and the upper wall of the exit of the nozzle, and with the increase of the length-to-diameter ratio, the deformation amount of the nozzle gradually increases. The maximum deformation of the upper and lower walls of the serpentine nozzle occurs in the downstream region of the first bend of the serpentine nozzle. The fluid-structure coupling effect has an influence on the flow field characteristics and aerodynamic performance of the serpentine nozzle. When the length-to-diameter ratio is 2.4, the influence of fluid-structure coupling effect is lowest, and the total pressure recovery coefficient decreases by 0.40%, the flow coefficient decreases by 5.34%, and the thrust coefficient decreases by 0.92%. When the length-to-diameter ratio is 3, the influence of fluid-structure coupling effect is highest, and at this time, the total pressure recovery coefficient decreases by 0.48%, the flow coefficient decreases by 5.95%, and the thrust coefficient decreases by 1.12%.

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“…Several studies presented simulations and experimental observations of the flow evolution within curved and S-shaped ducts for ideal gases (see e.g. Vakili et al 1983;Harloff et al 1993;Crowe & Martin 2015;Sun & Ma 2022). In many applications, however, the thermodynamic operating conditions require accounting for complex thermodynamic models, and entail the possibility of observing thermodynamic and gasdynamic non-ideal effects.…”

Section: Introductionmentioning

confidence: 99%

Ideal and non-ideal planar compressible fluid flows in radial equilibrium

Gajoni,

Guardone

2023

J. Fluid Mech.

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Two-dimensional compressible flows in radial equilibrium are investigated in the ideal dilute-gas regime and the non-ideal single-phase regime close to the liquid–vapour saturation curve and the critical point. Radial equilibrium flows along constant-curvature streamlines are considered. All properties are therefore independent of the tangential streamwise coordinate. A differential relation for the Mach number dependency on the radius is derived for both ideal and non-ideal conditions. For ideal flows, the differential relation is integrated analytically. Assuming a constant specific heat ratio $\gamma$ , the Mach number is a monotonically decreasing function of the radius of curvature for ideal flows, with $\gamma$ being the only fluid-dependent parameter. In non-ideal conditions, the Mach number profile also depends on the total thermodynamic conditions of the fluid. For high molecular complexity fluids, such as toluene or hexamethyldisiloxane, a non-monotone Mach number profile is admissible in single-phase supersonic conditions. For Bethe–Zel'dovich–Thompson fluids, non-monotone behaviour is observed in subsonic conditions. Numerical simulations of subsonic and supersonic turning flows are carried out using the streamline curvature method and the computational fluid dynamics software SU2, respectively, both confirming the flow evolution from uniform flow conditions to the radial equilibrium profile predicted by the theory.

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Effect of Geometry on Exit Temperature from Serpentine Exhaust Nozzles

Cited by 14 publications

References 22 publications

Influences of key parameters on flow features in the curved ducts with equal area

Influences of key parameters on flow features in the curved ducts with equal area

Investigation on influence mechanism of length-to-diameter ratio on fluid-structure interaction characteristic of serpentine nozzle

Ideal and non-ideal planar compressible fluid flows in radial equilibrium

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