Measurement of the Thermal Conductivity of Noble Gases in the Temperature Range 1500 to 5000 Deg Kelvin

1966 ◽  
Vol 88 (1) ◽  
pp. 52-55 ◽  
Author(s):  
D. J. Collins ◽  
W. A. Menard
Keyword(s):  
Thermal Conductivity ◽  
Thermal Boundary Layer ◽  
Density Variation ◽  
Reflected Shock Wave ◽  
Transfer Rates ◽  
Temperature Range ◽  
Reflected Shock ◽  
End Wall ◽  
The Relationship ◽  
Best Fit

The thermal conductivities of argon, neon, and krypton in the temperature range 1500 to 5000 deg Kelvin have been deduced from the measurement of heat transfer rates from the heated gases to the end wall in the reflected shock wave. Pressures ranged from approximately 1/2 atm to 3 atm. The relationship between thermal conductivity and temperature was assumed to be of the form k = aTb. The constant “b” was determined by a best fit to the data and the constant “a” by the known values of “k” below 1500 K. The effect of density variation in the thermal boundary layer was found to be significant in reducing the data; some previous investigations have neglected this effect.

Development of Shock-Wave-Powered Actuators for High Speed Positioning

2011 ◽  
Vol 5 (6) ◽  
pp. 786-792 ◽  
Author(s):  
Akira Kotani ◽  
◽  
Toshiharu Tanaka ◽  
Atsushi Fujishiro ◽  
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
High Speed ◽  
Initial Conditions ◽  
Reflected Shock Wave ◽  
Compressive Wave ◽  
Reflected Shock ◽  
Temperature And Pressure ◽  
Driver Section ◽  
End Wall

A shock wave is a compressive wave which propagates at supersonic speed. A shock wave is generated by the emission of energy for a very short duration by high speed phenomena, such as explosions, discharges, collisions, high speed flights, etc. Shock tube experiments have played an important role in the field of high speed gas dynamics. A shock tube is usually divided by a diaphragm into a driver section and a driven section. Generally, the initial conditions of the driver and driven sections are high and low pressure, respectively. When the diaphragm breaks, a shock wave is generated in the driven section. The density, temperature and pressure of the gas behind the shock wave rise discontinuously. The shock wave arrives at the end wall of the tube, and a reflected shock wave is generated by the reflection from the wall. The quantities behind the reflected shock wave rise further. If the shock wave can be generated continuously without the diaphragm needing to be changed, this phenomenon could possibly be applied to an actuator having a piston that moves at high speed. In this study, equipment powered by a shock wave is produced, and its performance is examined. The results show that piston movement generated by a shock wave is faster than that which is not and that the piston speeds depend on the initial conditions. Also, the characteristic of the actuator powered by the shock wave is revealed.

scholarly journals Application of a magnetic mass spectrometer to ionization studies in impure shock-heated argon

1966 ◽  
Vol 25 (4) ◽  
pp. 641-656 ◽  
Author(s):  
B. Sturtevant
Keyword(s):  
Mass Spectrometer ◽  
Reflected Shock Wave ◽  
Impurity Level ◽  
Reaction Products ◽  
Ion Diffusion ◽  
Reflected Shock ◽  
Magnetic Mass ◽  
Thermal Layer ◽  
End Wall

A study of the unique role of impurities in the initial stages of ionization relaxation in shock-heated argon, using a sampling mass spectrometer to determine the ionic products of the reaction, is described. The ions are extracted from the shock tube through a small orifice in the end wall after they have diffused through the dense thermal layer adjacent to the wall from the ionizing gas behind the reflected shock wave. The ion diffusion is analysed in detail to assess the possibility that the sampling process alters the reaction products. It is shown that this is unlikely because the impurities are in dilute concentration and the reaction is studied in its initial stages. This mode of sampling is compared with others.The experiments were conducted in argon at temperature of 16,600 °K and pressure of 16 mmHg with an estimated impurity level of 300 parts per million. A surprisingly large number of different ions were detected during the initial stages of ionization. O+ and H+ were found in much greater amounts than any of the other products, each being about five times more abundant than A+. The results suggest that H2O is probably quite generally the most important impurity in thermal-ionization experiments, and that ionization ‘incubation’ is due to dissociation of molecular impurities (especially H2O) before ionization commences. Possible explanations of the well-known efficiency of small amounts of impurities in initiating ionization are discussed.

Theory of heat transfer to a shock-tube end-wall from an ionized monatomic gas

1965 ◽  
Vol 21 (4) ◽  
pp. 659-672 ◽  
Author(s):  
James A. Fay ◽  
Nelson H. Kemp
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Shock Tube ◽  
Ambipolar Diffusion ◽  
Plasma Sheath ◽  
Heating Rates ◽  
Reflected Shock ◽  
End Wall ◽  
Monatomic Gas

This paper deals with the calculation of the convective heat transfer rate to the end-wall of a shock tube from a monatomic gas heated by a reflected shock. We consider a range of shock strengths for which the equilibrium thermodynamic state is one of appreciable ionization. The resulting boundary-layer problem involves the thermal conductivity and ambipolar diffusion coefficient for a partially ionized monatomic gas. The formulation here is restricted to the case of a catalytic wall and equal temperatures for all species. We ignore the effect of the plasma sheath at the wall. Consideration is given to three limiting cases for which similarity-type solutions of the boundary-layer equations may be found: (1) complete thermodynamic equilibrium behind the reflected shock and within the boundary layer; (2) equilibrium behind the reflected shock, but no gas-phase recombination in the boundary layer; (3) no ionization in either region. Numerical calculations are carried out for argon using estimated values of thermal conductivity and ambipolar diffusion, and compared with shock-tube experiments of Camac & Feinberg (1965). For no ionization, calculations were made with thermal conductivity varying as the ¾ power of the temperature, which fits the estimates of Amdur & Mason (1958) up to 15,000°K. Excellent agreement with experiment is obtained confirming an extrapolation of this power law up to 75,000°K. For ionized cases, based on estimates of Fay (1964), the theory predicts heating rates 20–40% lower than measured values. Some possible reasons for this discrepancy are discussed.

High Temperature Thermal Conductivity of Rare Gases and Gas Mixtures

1968 ◽  
Vol 90 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Richard A. Matula
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Shock Tube ◽  
Voltage Drop ◽  
Gas Mixtures ◽  
Reflected Shock Wave ◽  
Reflected Shock ◽  
Least Squares Fit ◽  
Theoretical Predictions ◽  
Relationship Of

The thermal conductivities of pure argon, pure xenon, and of three helium-argon mixtures have been determined in the temperature range 650–5000 deg K by measuring heat transfer rates from shock heated gases to the end wall of a shock tube. The heat transfer rate was measured by monitoring the time dependence of the voltage drop across a thin-film gage mounted in the end cap of the shock tube. During the course of the experiments, the pressure of the test gas behind the reflected shock wave ranged from approximately 1/3 to 2 atmospheres. In all cases, the temperature dependence (T) of the thermal conductivity (K) was assumed to follow a power law relationship of the form K/Kw = (T/Tw)b where Kw is the established value of the gas conductivity at the reference temperature (Tw) which was chosen near room temperature. The parameter b was evaluated by applying a least squares fit to the experimental data. Theoretical values of the conductivity of all of the gases studied were computed utilizing the Lennard-Jones (6–12) potential. In the case of the gas mixtures, an empirical combining rule was used to relate the force constants between unlike atoms to the known constants between like atoms. The experimental and theoretical results for the pure gases are in good agreement. The experimental and theoretical values of the mixture conductivities are within 10–20 percent, and as expected the theoretical predictions are least accurate for equimolar mixtures.

The Effective Thermal Conductivity of Porous Polymethacrylimide Foams

2014 ◽  
Vol 609-610 ◽  
pp. 196-200 ◽  
Author(s):  
Peng Yue ◽  
Lin Qiu ◽  
Xing Hua Zheng ◽  
Da Wei Tang
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Formation Mechanism ◽  
3Ω Method ◽  
Temperature Range ◽  
Different Temperatures ◽  
The Relationship

A freestanding sensor-based 3ω method was employed to measure the effective thermal conductivity of porous polymethacrylimide (PMI) foams with different densities at different temperatures. Experimental data showed that within the measuring temperature range, the effective thermal conductivity increased with temperature. Moreover, the formation mechanism of the relationship between the effective thermal conductivity and temperature was analyzed in this paper.

A conjugate axisymmetric model of a high-pressure shock-tube facility

2014 ◽  
Vol 24 (4) ◽  
pp. 873-890 ◽  
Author(s):  
Mouna Lamnaouer ◽  
Alain Kassab ◽  
Eduardo Divo ◽  
Nolan Polley ◽  
Rodrigo Garza-Urquiza ◽  
...  
Keyword(s):  
Shock Tube ◽  
Hot Spots ◽  
Conjugate Heat Transfer ◽  
Reflected Shock Wave ◽  
Transfer Model ◽  
Pressure Shock ◽  
Content Type ◽  
Reflected Shock ◽  
Boundary Layer Interaction ◽  
End Wall

Purpose – An axisymmetric shock-tube model of the high-pressure shock-tube facility at the Texas A&M University has been developed. The shock tube is non-conventional with a non-uniform cross-section and features a driver section with a smaller diameter than the driven section. The paper aims to discuss these issues. Design/methodology/approach – Computations were carried out based on the finite volume approach and the AUSM+ flux-differencing scheme. The adaptive mesh refinement algorithm was applied to the time-dependent flow fields to accurately capture and resolve the shock and contact discontinuities as well as the very fine scales associated with the viscous effects. The incorporation of a conjugate heat transfer model enhanced the credibility of the results. Findings – The shock-tube model is validated with simulation of the bifurcation phenomenon and with experimental data. The model is shown to be capable of accurately simulating the shock and expansion wave propagations and reflections as well as the flow non-uniformities behind the reflected shock wave as a result of reflected shock/boundary layer interaction or bifurcation. The pressure profiles behind the reflected shock wave agree with the experimental results. Originality/value – This paper presents one of the first studies to model the entire flow field history of a non-uniform diameter shock tube with a conjugate heat transfer model beginning from the bursting of the diaphragm while simultaneously resolving the fine features of the reflected shock-boundary layer interaction and the post-shock region near the end-wall, at conditions useful for chemical kinetics experiments. An important discovery from this study is the possible existence of hot spots in the end-wall region that could lead to early non-homogeneous ignition events. More experimental and numerical work is needed to quantify the hot spots.

Reflexion of a weak shock wave with vibrational relaxation

1974 ◽  
Vol 65 (2) ◽  
pp. 337-363 ◽  
Author(s):  
Ching-Mao Hung ◽  
Richard Seebass
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Asymptotic Expansions ◽  
Thermal Boundary Layer ◽  
Weak Shock ◽  
Reflected Shock Wave ◽  
Adiabatic Wall ◽  
Reflected Shock ◽  
Isothermal Wall ◽  
Non Equilibrium

The structure of a shock wave in a vibrationally relaxing gas undergoing reflexion from a plane wall is examined. The shock wave is assumed to be weak, and departures from thermodynamic equilibrium are assumed small; both an adiabatic and an isothermal wall are considered. The flow field is divided into three regions: a far-field region, an interaction region, and, for the isothermal-wall case, a thermal boundary layer. Different asymptotic expansions are determined for the various regions through the method of matched asymptotic expansions. In the region far from the wall, a non-equilibrium Burgers equation governs the motion and the incident and the reflected shock wave structures. During reflexion, a non-equilibrium wave equation applies; its first-order terms are equivalent to an acoustic approximation. Heat conduction to the wall is modelled by an isothermal wall boundary condition which requires the introduction of a thermal boundary layer adjacent to the wall. This thermal boundary layer is thin and the adiabatic-wall result provides the outer solution for treating this layer. This thermal layer affects the structure of the reflected wave.

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