Research On The Effect Of Real-gas Effect On Hypersonic Inlet

In hypersonic flight,physical and chemical phenomena such as dissociation,ionization,radiation and ablation occur in the air,and the real-gas effect is not negligible.In this paper,a gas model simulating the real-gas effect is established.The effects of the calorically perfect gas model and the chemically reacting gas model on the oblique wedge flow and the shock wave boundary layer interaction are compared and analyzed,and numerical simulation researches were carried out on the flow characteristics of the hypersonic inlet at Mach 10.Firstly,the chemically reacting gas model was established based on the Park-I's seven-component six-reaction model dynamics model.Based on the experimental results,the grid-independent,turbulence model and wall conditions were numerically verified and a credible numerical simulation method is obtained.Then,the influence of real-gas effect on the oblique wedge flow and the shock wave boundary layer interaction are studied under different gas models.The results show that the influence of real-gas effect makes the wall temperature drop and density rise.The boundary layer thickness and shock angle of wedge from the numerical results of chemically reacting gas model are smaller than that from calorically perfect gas model.With the increase of Mach number of free stream,the difference of boundary layer thickness increases gradually.With the increase of wedge angle,the difference of shock angle between the calorically perfect gas model and the chemically reacting gas model decreases.The boundary layer is easier to be separated under the calorically perfect gas model.The separation bubble size is larger than that under the chemically reacting gas model.With the increase of the angle of shock generator,the real-gas effect is more significant,the degree of oxygen dissociation increases,and the difference between the dimensionless dimensions of the separation bubble under the two gas models is larger.Then,the effects of different gas models on the flow characteristics of the hypersonic inlet at Mach 10 are studied.Compared to the numerical results from the calorically perfect gas model,the results from the chemically reacting gas model show that the Mach number of the throat become larger,the total pressure recovery coefficient increases by 2.2%,the flow coefficient of the inlet increases by 0.93%,and pressure ratio of the throat is reduced.The self-starting Mach number of the inlet decrease from Mach 10.1 to Mach 8.0 under the chemically reacting gas model which makes the inlet easier to start;The effect of the real-gas effect is most obvious on the smaller total compression angle.When the shoulder transition radius is around 1500 mm,the effect of real-gas effect on the performance of intake port is the largest.Finally,the effects of different conditions on the performance of the inlet under the chemically reacting gas model are studied.The results show that the real-gas effect is not significant at the condition of cold wall.The degree of dissociation reaction is deepened at the condition of hot wall.As the oxygen mass fraction in the free stream increases,the Mach number of the inlet throat,the pressure recovery coefficient decreases,and the flow coefficient increases.Under the condition of wind tunnel inflow,the boundary layer is thinner which makes the dissociation reaction hardly occur.Compared with the condition of real flight,the Mach number of the throat decreases and the throat pressure ratio increases.At the same time,the total pressure recovery coefficient increases by 7.1% and the flow coefficient increases by 2.1% at the condition of the wind tunnel.