Evaluation of real-gas phenomena in high-enthalpy aerothermal test facilities - A review

We propose an approach for the design of the subsonic part of plane and axisymmetric Laval nozzles for real gases. The proposed approach is based on the hodograph method and allows one to solve the inverse design problem directly. Real gas effects are taken into consideration using the chemical equilibrium model. We present nozzle contours computed with the proposed method for a stoichiometric methane-air mixture. Results confirm that real gas effects have a strong influence on the nozzle shape. The described method can be used in the design of nozzles for rocket engines and for high-enthalpy wind tunnels.

Download Full-text

The interaction of a shock wave with a laminar boundary layer at a compression corner in high-enthalpy flows including real gas effects

Journal of Fluid Mechanics ◽

10.1017/s0022112097005673 ◽

1997 ◽

Vol 342 ◽

pp. 1-35 ◽

Cited By ~ 36

Author(s):

S. G. MALLINSON ◽

S. L. GAI ◽

N. R. MUDFORD

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Shock Wave ◽

Gas Flows ◽

Perfect Gas ◽

Experimental Conditions ◽

Real Gas ◽

High Enthalpy ◽

Compression Corner ◽

Real Gas Effects

The high-enthalpy, hypersonic flow over a compression corner has been examined experimentally and theoretically. Surface static pressure and heat transfer distributions, along with some flow visualization data, were obtained in a free-piston shock tunnel operating at enthalpies ranging from 3 MJ kg−1 to 19 MJ kg−1, with the Mach number varying from 7.5 to 9.0 and the Reynolds number based on upstream fetch from 2.7×104 to 2.7×105. The flow was laminar throughout. The experimental data compared well with theories valid for perfect gas flow and with other relevant low-to-moderate enthalpy data, suggesting that for the current experimental conditions, the real gas effects on shock wave/boundary layer interaction are negligible. The flat-plate similarity theory has been extended to include equilibrium real gas effects. While this theory is not applicable to the current experimental conditions, it has been employed here to determine the potential maximum effect of real gas behaviour. For the flat plate, only small differences between perfect gas and equilibrium gas flows are predicted, consistent with experimental observations. For the compression corner, a more rapid rise to the maximum pressure and heat transfer on the ramp face is predicted in the real gas flows, with the pressure lying slightly below, and the heat transfer slightly above, the perfect gas prediction. The increase in peak heat transfer is attributed to the reduction in boundary layer displacement thickness due to real gas effects.

Download Full-text

High-enthalpy flow over a rearward-facing step – a computational study

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.29 ◽

2012 ◽

Vol 695 ◽

pp. 405-438 ◽

Cited By ~ 12

Author(s):

N. R. Deepak ◽

S. L. Gai ◽

A. J. Neely

Keyword(s):

Reynolds Number ◽

Computational Study ◽

Finite Rate ◽

Real Gas ◽

High Enthalpy ◽

Flow Features ◽

The Face ◽

Real Gas Effects ◽

Computational Fluid Dynamics Cfd ◽

Two Temperature

AbstractHypersonic, high-enthalpy flow over a rearward-facing step has been numerically investigated using computational fluid dynamics (CFD). Two conditions relevant to suborbital and superorbital flow with total specific enthalpies of $26$ and $50~\mathrm{MJ} ~{\mathrm{kg} }^{\ensuremath{-} 1} $, are considered. The Mach number and unit Reynolds number per metre were 7.6, 11.0 and $1. 82\ensuremath{\times} 1{0}^{6} $, $6. 23\ensuremath{\times} 1{0}^{5} $ respectively. The Reynolds number based on the step height was correspondingly $3. 64\ensuremath{\times} 1{0}^{3} $ and $12. 5\ensuremath{\times} 1{0}^{2} $. The computations were carried out assuming the flow to be laminar throughout and the real gas effects such as thermal and chemical non-equilibrium are studied using Park’s two-temperature model with finite-rate chemistry and Gupta’s finite-rate chemistry models. In the close vicinity of the step, detailed quantification of flow features is emphasised. In particular, the presence of the Goldstein singularity at the lip and separation on the face of the step have been elucidated. Within the separated region and downstream of reattachment, the influence of real gas effects has been identified and shown to be negligible. The numerical results are compared with the available experimental data of surface heat flux downstream of the step and reasonable agreement is shown up to 30 step heights downstream.

Download Full-text