Experimental studies of supersonic film cooling with shock wave interaction

Bao

Advances in Mechanical Engineering

2014

Supersonic film cooling is an efficient method to cool the engine with extremely high heat load. In order to study supersonic film cooling in a real advanced engine, a two-dimensional model of the hypersonic inlet in a scramjet engine with supersonic film cooling in the isolator is built and validated through experimental data. The simulation results show that the cooling effect under different coolant injection angles does not show clear differences; a small injection angle can ensure both the cooling effect and good aerodynamic performances (e.g., flow coefficient) of the hypersonic inlet. Under selected coolant injection angle and inlet Mach number, the cooling efficiency increases along with the injection Mach number of the coolant flow, only causing a little total pressure loss in the isolator. Along with the increase of the inlet Mach number of the hypersonic inlet, the cooling efficiency does not present a monotonic change because of the complex shock waves. However, the wall temperature shows a monotonic increase when the inlet Mach number increases. The mass flow rate of coolant flow should be increased to cool the engine more efficiently according to the mass flow rate of the main stream when the inlet Mach number increases.

Section: Introductionmentioning

confidence: 84%

Numerical Analysis of Supersonic Film Cooling in Supersonic Flow in Hypersonic Inlet with Isolator

Bao

Advances in Mechanical Engineering

2014

“…The inlet static pressures of the film coolant and the mainstream are equal in order to avoid the effect of inherent shock waves caused by the inequality of the static pressure between the mainstream and the film coolant at the exit of the slot. 34 The mainstream is air and the film coolant is high-temperature gaseous n-Decane. The main flow parameters are shown in Table 4.…”

Section: Modelmentioning

confidence: 99%

“…However, they found that film cooling almost had no effect on the peak heat flux at the shock impingement position. The experiments of Kanda et al 34 considered the transfer characteristic of energy, mass, and momentum in the shock wave interaction region under different shock strengths and different impingement positions. The shock wave interaction had little effect on film cooling effectiveness and mixing between the mainstream and the film coolant from their research.…”

Section: Introductionmentioning

confidence: 99%

Interaction mechanism between shock waves and supersonic film cooling with cracking reaction

Zuo

Proceedings of the Institution of Mechanical Engineers, Part G:

Qin

et al. 2019

In order to understand the interaction mechanism between shock waves and supersonic film cooling with cracking reaction, supersonic film cooling using gaseous hydrocarbon fuel as coolant in terms of cracking reaction of the coolant, with and without shock waves interaction, is investigated numerically. Theoretically, cracking reaction may be accelerated by the shock wave interaction, which may enhance the mixing of the coolant and absorb heat, which will lead to contradictory effects on supersonic film cooling. However, it turns out that, with shock waves interaction, cracking reaction only absorbs more heat but barely has any effect on the mixing either locally or further downstream due to the momentum change caused by the reaction is extremely small and the energy change plays the dominate role. It is worth mentioning that oblique shock wave causes energy accumulation in the shock wave interaction region, which deteriorates supersonic film cooling. However, with the cracking reaction considered, the negative effect brings by the oblique shock wave is weakened by the cracking reaction due to the increment of chemical heat absorption caused by the energy change. It is found that the absolute temperature in the shock wave interaction and the relative temperature increment caused by the shock wave interaction to be the decisive factors of the chemical heat absorption increment, especially for high absolute temperature or relative temperature increments, and the effect of the local reactant concentration plays the dominant role. Furthermore, the extent of weakened chemical reaction on the negative effect due to the oblique shock wave depends not only on the chemical heat absorption but also on the local absolute temperature.

Journal of Spacecraft and Rockets

“…The experiments of Kanda et al [9] also demonstrated the damaging effects of shock waves on supersonic film cooling. However, Ochs et al [10] investigated the influence of an oblique shock wave on film cooling in a supersonic wind tunnel, with the results showing that the shock wave had little effect on the film-cooling effectiveness.…”

Section: Introductionmentioning

confidence: 95%

Effect of Coolant Inlet Conditions on Supersonic Film Cooling

Peng

Jiang

2015

The influence of the coolant gas inlet height and Mach number on supersonic film cooling were analyzed numerically while keeping the mainstream inlet conditions and coolant mass flow rate unchanged for a given coolant gas. The results indicate that, for the same coolant gas without a shock wave or with a weak shock wave, the supersonic film cooling mainly depends on the coolant gas flow rate and has little relationship to the coolant inlet height or the Mach number. For the cases with a strong shock wave, reducing the coolant inlet height (i.e., increasing the Mach number) improved the supersonic film cooling. The main reason is that the coolant gas velocity increases when the coolant inlet height is reduced for a given coolant mass flow rate, which increases the coolant flow momentum, and so the coolant gas more effectively resists the interference of the shock wave. The results also show that helium is more easily affected by the coolant inlet conditions than methane or nitrogen when the inlet Mach number is the same for the same inlet height. Nomenclature c = mass concentration, kg∕m 3 c p = specific heat, J∕kg · K D = diffusion coefficient, m 2 ∕s E t = total energy, J∕kg e = internal energy, J∕kg k = turbulent kinetic energy, m 2 ∕s 2 Ma = Mach number m = flow rate, kg∕s Pr = Prandtl number p = pressure, Pa r = recovery factor T = temperature, K u, v = velocity, m∕s x = distance from the slot along the surface, m y = coordinate normal to the surface, m Sc = Schmidt number s = coolant stream inlet height, mm γ = specific heat ratio η = adiabatic effectiveness μ = dynamic viscosity, Pa · s ρ = density, kg∕m 3 ω = dissipation of turbulent kinetic energy, 1∕s τ = shear stress, kg∕m · s 2 Subscripts aw = adiabatic c = coolant stream r = recovery condition ∞ = freestream