An Evaluation of High Temperature Airframe Seals for Advanced Hypersonic Vehicles

DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.; Drlik, Gary J.

doi:10.2514/6.2007-5743

Cited by 8 publications

(9 citation statements)

References 7 publications

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“…The mechanical properties of C/SiC are related to the density, thus the compression characteristics of the C/SiC spring are also highly related to the density. When the spring dimensions are fixed (D = 18 mm, d = 2.0 mm, t = 5 mm, n = 5, twist number = 50 twist/m), the spring constant is 1.10 N/mm when the density is 1.74 g/cm 3 . The spring constant remains almost the same till the density reaches 1.81 g/cm 3 , which increases dramatically to 1.87 N/mm when the density is 1.83 g/cm 3 (Fig.…”

Section: Effects Of Density On Spring Constantmentioning

confidence: 99%

“…The seal of the gaps between panels is a key technology to fulfill TPS functions, and there are many routes to solve the problem. One route is to use flexible materials combined with springs, and these springs must be used at high temperatures . Up to now, few kinds of springs can be used above 1200°C in oxidative atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…One route is to use flexible materials combined with springs, and these springs must be used at high temperatures. 3 Up to now, few kinds of springs can be used above 1200°C in oxidative atmosphere. The expensive Inconel alloy spring is widely used for its simple fabrication process, excellent compression restoration, and stability, but it can only be applied at the temperatures below 900°C because of the potential oxidation, creep deformation, and stress relaxation.…”

Section: Introductionmentioning

confidence: 99%

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A Simple Way to Prepare C/SiC Spring

Chen

Zhang

et al. 2013

Int J Applied Ceramic Tech

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A new method to form helical C/SiC spring is proposed. Using paraffin mold as a sacrificial core, unidirectional carbon fiber bundles (infiltrated with resin) are wrapped around the mold to form helical spring, and after resin curing, the mold is removed, leaving a preform of C/SiC spring. Following densification is finished with precursor infiltration and pyrolysis (PIP) process. The spring constant of C/SiC spring reaches 7.88 N/mm and could be regulated by varying composite density and carbon fiber content. The spring properties could be improved by twisting the carbon fibers at 35-50 twist/m. The restoration ratio reaches 100%, but energy dissipation happens during unloading process. After oxidation in air at 1200°C for 10 min, the spring has an 82.4% spring constant remaining ratio.

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Section: Effects Of Density On Spring Constantmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Simple Way to Prepare C/SiC Spring

Chen

Zhang

et al. 2013

Int J Applied Ceramic Tech

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“…High‐temperature sealing materials and structures thus have become one of the bones of contention. Among the various thermal sealing structures, ceramic wafer seal structure 1 has excellent thermal protection effect. The general requirements of ceramic wafer sealing materials include low density, low thermal conductivity, low hardness, high strength, high Young's modulus, low shear modulus, and good high temperature stability 2 .…”

Section: Introductionmentioning

confidence: 99%

Mechanical and thermal properties of light weight boron‐mullite Al₅BO₉

et al. 2020

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Al5BO9 is a promising thermal sealing material for hypersonic vehicles due to its low density, theoretically predicted low shear modulus, and low thermal conductivity. However, experimental investigations on the mechanical and thermal properties of bulk Al5BO9 have not been carried out. Herein, we report the mechanical and thermal properties of bulk Al5BO9 prepared by spark plasma sintering of solid‐state reaction synthesized Al5BO9 powders. The bulk (B), shear (G), and Young's (E) moduli are 148 GPa, 85 GPa, and 214 GPa, respectively, which are close to the theoretical values. The Pugh's ratio G/B is 0.574, indicating its intrinsic damage tolerance, which is also revealed by Hertzian contact test. The Vickers hardness (Hv) is 10.8 GPa, being lower than mullite. The flexural strength, compressive strength, and fracture toughness are, respectively, 277 ± 35 MPa, 814 ± 75 MPa, and 2.4 ± 0.3 MPa·m1/2, which are close to those of mullite. Al5BO9 has anisotropic coefficient of thermal expansion (CTE) in three crystallographic directions, ie αa = (4.40 ± 0.21) × 10−6 K−1, αb = (7.11 ± 0.18) × 10−6 K−1, αc = (6.70 ± 0.29) × 10−6 K−1 from Debye temperature to 1473 K, which are underpinned by its structural feature, ie lower αa is resulted from the edge‐shared AlO6 octahedron chains along the [100] direction. The average CTE is (6.05 ± 0.06) × 10−6 K−1. The thermal conductivity declines with temperature as κ = 1336.39/T + 1.97, consisting with predicted trend from Slack's model. The low thermal conductivity and low density guarantee Al5BO9 a promising candidate as ceramic wafer in the seal structure for hypersonic vehicles.

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“…These seals are necessary to limit the ingestion of high temperature gases into the gaps between panels or in control surface locations. Incursion of high temperature gases into vulnerable areas could result in reduced vehicle stability or potentially even loss of the vehicle and crew [1,2]. X-51A Waverider hypersonic flight failed the first test just because the thermal seal between the rear of the fuel-cooled engine and its vehicle mounted nozzle was not as tight as it needed to be.…”

Section: Introductionmentioning

confidence: 99%

A model for gas permeation in three-dimensional braided seal

Jing

Jiao

2017

Journal of Industrial Textiles

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High temperature three-dimensional (3D) braided seals are required for advanced hypersonic airframe applications to avoid a lot of hot air leaking into the internal structure. The gas permeation of 3D braided seals at room temperature was studied. According to Darcy’s Law, we present a computational model based on K-C equation and Kozeny theory for prediction. The model is combined with microstructure of the 3D four-directional braided seal and 3D five-directional braided seal, to predict the gas permeation as a function of fiber volume fraction, compression ratio, and pressure drop across the seal. The comparison showed that the predictions are in good agreement well with the experimental data. The 3D four-directional braided seal and 3D five-directional braided seal were fabricated and their gas permeation was measured in order to verify the prediction model.

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An Evaluation of High Temperature Airframe Seals for Advanced Hypersonic Vehicles

Cited by 8 publications

References 7 publications

A Simple Way to Prepare C/SiC Spring

A Simple Way to Prepare C/SiC Spring

Mechanical and thermal properties of light weight boron‐mullite Al₅BO₉

A model for gas permeation in three-dimensional braided seal

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An Evaluation of High Temperature Airframe Seals for Advanced Hypersonic Vehicles

Cited by 8 publications

References 7 publications

A Simple Way to Prepare C/SiC Spring

A Simple Way to Prepare C/SiC Spring

Mechanical and thermal properties of light weight boron‐mullite Al5BO9

A model for gas permeation in three-dimensional braided seal

Contact Info

Product

Resources

About

Mechanical and thermal properties of light weight boron‐mullite Al₅BO₉