Abstract
From the analysis of the isentropic limit of weak compression shock waves, oblique shock waves in which the post-shock Mach number is larger than the pre-shock Mach number, named non-ideal oblique shocks, are admissible in substances characterized by moderate molecular complexity and in the close proximity to the liquid–vapour saturation curve. Non-ideal oblique shocks of finite amplitude are systematically analysed, clarifying the roles of the pre-shock thermodynamic state and Mach number. The necessary conditions for the occurrence of non-ideal oblique shocks of finite amplitude are singled out. In the parameter space of pre-shock thermodynamic states and Mach number, a new domain is defined which embeds the pre-shock states for which the Mach number increase can possibly take place. The present findings are confirmed by state-of-the-art thermodynamic models applied to selected commercially available fluids, including siloxanes and hydrocarbons currently used as working fluids in renewable energy systems.
Highlights
The design of aerodynamic devices and systems often requires special care to account for shock wave formation and related losses
The goal of the present paper is to investigate classical compression shock waves of finite amplitude to complement the previous study of Gori et al (2017), where non-ideal oblique shock waves are studied using the simple van der Waals model
Sulphur hexafluoride exhibits a fairly simpler configuration as a result of its saturated vapour boundary being non-retrograde. In this case, according to the nomenclature used in figure 5, the portion of Pre-shock limit locus (PSLL) on the right-hand side of point AJτ (comprising pre-shock states for shock curves featuring dMH(β, A)/dβ = 0 when MB = MA) extends to a point on the VLE line
Summary
The design of aerodynamic devices and systems often requires special care to account for shock wave formation and related losses. The variation of the thermodynamic and kinematic quantities across the shock wave is determined by the Mach number of the flow ahead of the shock, relative to the shock front itself, in dilute-gas flows to which the theory of perfect gases can be reasonably applied. If instead the thermodynamic states of the fluid cannot be accurately described by means of the perfect-gas model, a more or less noticeable dependence on the pre-shock thermodynamic state, say the values of the pre-shock temperature and pressure, is observed. Most of the features of shock waves and, more in general, the nonlinear dynamics of compressible fluids, depends on the evolution of the speed. √ of sound c = (∂P/∂ρ)s along isentropic transformations, where P, ρ and s denote the fluid pressure, density and entropy, respectively. The sound-speed isentropic variation is expressed in non-dimensional form by the parameter Γ , ρ ∂c
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
