162
6 Hypersonic Wind Tunnels
to supply a square or rectangular test section. In the latter configuration, the effect
of a plasma flow on different types of surface coating materials can be studied by
placing them on the flat wall of the test section. The effect of pressure gradients on
these materials can be also tested on an inclined plate placed at the outlet of the test
section.
The main features of this facility are:
– electrical power of 4 times 5 MW,
– stagnation pressure ranging from 5 to 60 bar,
– dimensionless stagnation enthalpy ranging from 60 to 170 (air),
– test time is approximately 1 min, with the possibility of variation of the operating
point during operation.
Since the plasma jet exhausts to the atmosphere the expansion ratios are limited
and the facility is used for:
– stagnation point test, where the test chamber is equipped with a contoured axisymmetric nozzle providing a uniform flow of Mach numbers of 1.7, 2, 4 or 2.6; the
models subjected to the plasma jet are typically 50 mm in diameter and can experience a stagnation pressure of 5–50 bar, where pressure, heat flow, temperature
and ablation measurements are performed;
– more global assessment in the closed square test section or inclined plate configuration where different nozzles with rectangular or square outlet sections allows
for a Mach 1.7 or 2.4; the test samples, typically 200 mm long and 40 mm wide,
can be subjected to pressures of 1–15 bar and heat fluxes of 1–25 MW/m
2 ; pressure, heat transfer, temperature (wall or material) or ablation measurements can
be performed.
The JPHP facility shown in Fig. 6.36 allows for higher pressure testing (greater
than 100 bar), so as to ensure representativeness for most possible missions for the
vehicles concerned.
The main characteristics of this facility which also operates on Huels principle
are:
– electric power 9 MW,
– stagnation pressure greater than 100 bar,
– dimensionless stagnation enthalpy from 60 to 140,
– test duration of the order of one minute.
Axisymmetric nozzles can provide Mach 1.7, 2.4 or 2.6 flows. A multi-test rotary
arm permits successive positioning of up to eight samples or pressure or temperature
probes in front of the plasma jet (stagnation point configuration). Test specimens
typically have a diameter of 50 mm and their temperature and ablation rate can be
measured throughout the run by optical means (cameras) or more intrusive techniques
(thermocouples).
In Huels type generators, the length of the electric arc is free and can therefore
fluctuate, which limits the accessible powers. In the latest technology, the segmented
generator uses a predefined arc length to reach higher power levels. The schematic
6 Hypersonic Wind Tunnels
to supply a square or rectangular test section. In the latter configuration, the effect
of a plasma flow on different types of surface coating materials can be studied by
placing them on the flat wall of the test section. The effect of pressure gradients on
these materials can be also tested on an inclined plate placed at the outlet of the test
section.
The main features of this facility are:
– electrical power of 4 times 5 MW,
– stagnation pressure ranging from 5 to 60 bar,
– dimensionless stagnation enthalpy ranging from 60 to 170 (air),
– test time is approximately 1 min, with the possibility of variation of the operating
point during operation.
Since the plasma jet exhausts to the atmosphere the expansion ratios are limited
and the facility is used for:
– stagnation point test, where the test chamber is equipped with a contoured axisymmetric nozzle providing a uniform flow of Mach numbers of 1.7, 2, 4 or 2.6; the
models subjected to the plasma jet are typically 50 mm in diameter and can experience a stagnation pressure of 5–50 bar, where pressure, heat flow, temperature
and ablation measurements are performed;
– more global assessment in the closed square test section or inclined plate configuration where different nozzles with rectangular or square outlet sections allows
for a Mach 1.7 or 2.4; the test samples, typically 200 mm long and 40 mm wide,
can be subjected to pressures of 1–15 bar and heat fluxes of 1–25 MW/m
2 ; pressure, heat transfer, temperature (wall or material) or ablation measurements can
be performed.
The JPHP facility shown in Fig. 6.36 allows for higher pressure testing (greater
than 100 bar), so as to ensure representativeness for most possible missions for the
vehicles concerned.
The main characteristics of this facility which also operates on Huels principle
are:
– electric power 9 MW,
– stagnation pressure greater than 100 bar,
– dimensionless stagnation enthalpy from 60 to 140,
– test duration of the order of one minute.
Axisymmetric nozzles can provide Mach 1.7, 2.4 or 2.6 flows. A multi-test rotary
arm permits successive positioning of up to eight samples or pressure or temperature
probes in front of the plasma jet (stagnation point configuration). Test specimens
typically have a diameter of 50 mm and their temperature and ablation rate can be
measured throughout the run by optical means (cameras) or more intrusive techniques
(thermocouples).
In Huels type generators, the length of the electric arc is free and can therefore
fluctuate, which limits the accessible powers. In the latest technology, the segmented
generator uses a predefined arc length to reach higher power levels. The schematic