Characteristics of a plasma wind tunnel for the development of thermal protection materials

2017 ◽  
Vol 121 (1240) ◽  
pp. 821-834 ◽  
Author(s):  
B. G. Hong ◽  
B. R. Kang ◽  
J. C. Choi ◽  
P. Y. Oh
Keyword(s):  
Wind Tunnel ◽  
Plasma Flow ◽  
Thermal Protection ◽  
Plasma Source ◽  
Carbon Composites ◽  
Diagnostic Systems ◽  
Supersonic Plasma ◽  
The Matrix ◽  
National University ◽  
Arc Plasma Torch

ABSTRACTThermal plasma wind tunnels with power of 0.4 MW and 2.4 MW have been constructed at Chonbuk National University (CBNU) in Korea. This facility is capable of producing a heat flux greater than 10 MW/m2, a level that is relevant for testing thermal protection materials that are used for re-entry vehicles in space transportation. A segmented arc plasma torch was adopted as a plasma source; this was designed to have high thermal efficiency and long life, and to produce a supersonic plasma flow with enthalpy greater than 10 MJ/kg. We investigated the characteristics of the supersonic plasma flow using intrusive and non-intrusive diagnostic systems. Ablation characteristics of potential thermal protection materials such as carbon/carbon composites and graphite were investigated with the plasma wind tunnel. Cracks and pores in the materials accelerated the erosion. For carbon/carbon composites, the pores grew and the cracks which occurred at the interfaces between the carbon fibres and the matrix propagated, while for the graphite, the erosion started at the pores and peeled off the surface.

An Experimental Study on the Ablation Properties of Carbon/Carbon Composites Using Thermal Plasma

2020 ◽  
Vol 12 (9) ◽  
pp. 1271-1277
Author(s):  
Philyong Oh ◽  
Hoseok Kim ◽  
Boram Kang ◽  
Bong Guen Hong
Keyword(s):  
Heat Flux ◽  
Wind Tunnel ◽  
Thermal Protection ◽  
Carbon Composites ◽  
Vacuum Plasma Spray ◽  
Thermoelectric Generators ◽  
Test Results ◽  
Erosion Rates ◽  
Vacuum Plasma ◽  
The Matrix

The ablation properties of two carbon/carbon (C/C) composites currently considered as thermal protection materials for radioisotope thermoelectric generators (RTGs) were investigated using a plasma wind tunnel with a heat flux between the range of 2–4 MW/m2. The ablation properties were identified through an analysis of erosion rates and microstructures after testing. During ablation, erosion reactions of the matrix were faster than those of fibers and pores, and the defects and cracks between the fibers and matrix grew. The fibers eroded from their outer surface and ablation led to the formation of sharp tapered tips. Lower density C/C composites appeared to lose more matrix than higher density C/C composites. The erosion rate increased with heat flux. The ablation properties were compared with the test results using a vacuum plasma spray (VPS) facility and an E-beam facility. It was shown that both thermochemical and thermomechanical erosion occurred via oxygen in the plasma flow, and a rapid high-pressure heat stream occurred in tests using the plasma wind tunnel while only thermal ablation occurred in tests using the VPS and E-beam facilities.

scholarly journals Prediction of Effective Thermal Conductivities of Four-Directional Carbon/Carbon Composites by Unit Cells with Different Sizes

2021 ◽  
Vol 11 (3) ◽  
pp. 1171
Author(s):  
Chang Xu ◽  
Zhihong Sun ◽  
Guowei Shao
Keyword(s):  
Carbon Fiber ◽  
Longitudinal Direction ◽  
Unit Cell ◽  
Carbon Composites ◽  
Temperature Boundary ◽  
The Matrix ◽  
Unit Cells ◽  
Experimental Values ◽  
Different Diameters ◽  
Thermal Conductivities

Two-unit cells developed to predict the effective thermal conductivities of four-directional carbon/carbon composites with the finite element method are proposed in this paper. The smaller-size unit cell is formulated from the larger-size unit cell by two 180° rotational transformations. The temperature boundary conditions corresponding to the two-unit cells are derived, and the validity is verified by the temperature and heat flux distributions at specific positions of the larger-size unit cell and the smaller-size unit cell. The thermal conductivities of the carbon fiber bundles and carbon fiber rods are measured firstly. Then, combined with the properties of the matrix, the effective thermal conductivities of the four-directional carbon/carbon composites are numerically predicted. The results in transverse direction predicted by the larger-size unit cell and the smaller-size unit cell are both higher than experimental values, which are 5.8 to 6.2% and 7.3 to 8.2%, respectively. In longitudinal direction, the calculated thermal conductivities of the larger-size unit cell and the smaller-size unit cell are 6.8% and 6.2% higher than the experimental results, respectively. In addition, carbon fiber rods with different diameters are set to clarify the influence on the effective thermal conductivities of the four-directional carbon/carbon composites.

The dynamics of supersonic plasma flow interaction with the magnetic arch

2019 ◽  
Vol 61 (3) ◽  
pp. 035001 ◽  
Author(s):  
M E Viktorov ◽  
S V Golubev ◽  
A V Vodopyanov
Keyword(s):  
Plasma Flow ◽  
Flow Interaction ◽  
Supersonic Plasma ◽  
Magnetic Arch

scholarly journals INVESTIGATION ON CORROSION PROPERTIES OF CARBON-CARBON COMPOSITES

2020 ◽  
pp. 154-160
Author(s):  
Yu.A. Gribanov ◽  
I.V. Gurin ◽  
V.V. Gujda ◽  
A.N. Bukolov ◽  
V.V. Kolosenko
Keyword(s):  
Heat Transfer ◽  
Composite Material ◽  
Corrosion Resistance ◽  
Carbon Composite ◽  
Carbon Composites ◽  
Content Increase ◽  
Corrosion Properties ◽  
Corrosive Media ◽  
The Matrix ◽  
Accident Conditions

The corrosion resistance of carbon-carbon composite materials (C–C composites) was studied in a corrosive media of coolant NaF+ZrF4 salt (a model heat-transfer) at 700 °С in the air flow. It has been shown that C–C composite material is resistant to the model heat-transfer even under conditions of critical temperature accident. The main mechanism that leads to the C–C composite corrosion is a mechanism of composite material oxidation due to the contact with the air. The study has evidenced that the C–C composite burn-up rate well correlates with the pyrocarbon matrix content in the composite, the matrix content increase by 2530% results in the composite corrosion resistance increase by a factor of 2–4. So, by developing corrosion-resistant carbon-carbon composites one has a problem of finding an optimum fiber-matrix ratio in the composite. It has been confirmed experimentally that by silication of C–C composites with the use of the methods which were developed in NSC KIPT it is possible to increase the service life of products under simulated accident conditions by a factor of 7–7.5.

Advanced Oxidation Protection System for Carbon-Carbon Composites

1989 ◽  
Author(s):  
D. A. Eitman ◽  
R. W. Kidd ◽  
R. B. Dirling
Keyword(s):  
Advanced Oxidation ◽  
High Strength ◽  
Carbon Composite ◽  
Protection System ◽  
Carbon Composites ◽  
Oxidation Protection ◽  
Low Thermal Expansion ◽  
The Matrix ◽  
Strength And Stiffness ◽  
Orthotropic Properties

Carbon-carbon composites possess a number of desirable attributes including low density, high strength and stiffness at temperatures well beyond the capabilities of refractory alloys, low thermal expansion coefficient, tailorable orthotropic properties, absence of strategic materials, and resistance to thermal shock, fatigue, and brittle failures. However, for many applications of interest (such as aircraft and aerospace vehicle structure and engines) resistance to oxidation in high-temperature air or engine exhaust streams is a requirement which is not satisfied by unprotected carbon-carbon composites. The elements of an advanced oxidation protection system for carbon-carbon composites are described in this paper. The system is comprised of both an oxidation resistant coating intended to provide the primary barrier to oxygen ingress and inhibitors added to the matrix of the carbon-carbon composite to increase its oxidation resistance without significant losses in mechanical properties. The composite inhibition system is designed to be complementary to the coating and to enhance its long-term performance. A description of the principal elements of the system is presented along with recent test data and current research directions.

Exploration on application of dredging thermal protection in the leading edge of the wing

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040105
Author(s):  
Xiao-Jun Zhu ◽  
Feng Li
Keyword(s):  
High Temperature ◽  
Wind Tunnel ◽  
Heat Pipe ◽  
Thermal Protection ◽  
Wind Tunnel Test ◽  
Leading Edge ◽  
Temperature Zone ◽  
Temperature Heat ◽  
Thermal Protection Structure ◽  
High Temperature Heat Pipe

Aiming at the severe aerodynamic heating problem in the leading edge of the hypersonic vehicle, in order to ensure the sharp shape of the leading edge of the wing, a dredging thermal protection structure is proposed, and the built-in high-temperature heat pipe structure is used to provide thermal protection for the leading edge of the wing. By means of numerical simulation and arc wind tunnel test, the dredging thermal protection structure of the leading edge of the wing is analyzed, and the thermal protection effect of the built-in high-temperature heat pipe is obtained. The numerical results show that under certain thermal conditions, the temperature at the leading edge of the wing decreases by 304 K, and the minimum temperature of the tail increases by 130 K. The heat flow is dredged from the high-temperature zone to the low-temperature zone, and the thermal load of the leading edge of the wing is weakened. The same result can be obtained by the arc wind tunnel test, which verifies the accuracy of the numerical method and the feasibility of the dredging thermal protection structure with high-temperature heat pipe embedded in the leading edge of the wing.

Microstructure of Pyrolytic Carbon Matrix in Carbon/Carbon Composites after Graphitization

2007 ◽  
Vol 336-338 ◽  
pp. 1270-1273 ◽  
Author(s):  
Wan Chang Sun ◽  
He Jun Li ◽  
Shou Yang Zhang ◽  
Yong Huang
Keyword(s):  
Polarized Light ◽  
Carbon Matrix ◽  
Pyrolytic Carbon ◽  
Interplanar Distance ◽  
Carbon Composites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Before And After ◽  
The Matrix ◽  
Microstructure Parameters

The morphologies and textures of the pyrolytic carbon matrix in 2D-C/C composites after graphitization were investigated by means of polarized light microscope (PLM) and high resolution transmission electron microscope (HRTEM). The microstructure parameters of the pyrolytic carbon matrix before and after graphitization were characterized with X-ray diffraction (XRD) technology. It was found that the interplanar distance of (002) planes (d002) of pyrolytic carbon matrix decreases, and the microcrystalline stack height (LC) increases after graphitization. Graphitization treatment resulted in a coarsening of the surface texture and in the formation of circumferential cracks within the matrix. The lattice fringes of the pyrolytic carbon matrix are continuous and longer in each domain and the (002) peak spot is smaller and more intense after graphitization.

Sign in / Sign up

Export Citation Format

Share Document