Calculate oblique shock wave angle, downstream Mach number, pressure/density/temperature ratios, and stagnation pressure loss for supersonic flow.
An oblique shock wave forms when supersonic flow encounters a wedge, ramp, or deflection. Unlike a normal shock (perpendicular to flow), an oblique shock is inclined at angle β to the freestream, deflecting the flow by angle θ while compressing, heating, and decelerating the gas.
This calculator solves the oblique shock relations. Given the upstream Mach number and deflection angle, it determines the shock angle β using an iterative solver, then computes all downstream properties: Mach number, static pressure ratio, density ratio, temperature ratio, stagnation pressure ratio, and entropy rise.
The tool handles the full range of supersonic Mach numbers from 1+ to hypersonic. It correctly identifies when the deflection angle exceeds the maximum for attached shocks (indicating a detached bow shock). A maximum deflection angle reference table helps engineers design inlet ramps and compressor cascades.
Oblique shock analysis is essential for supersonic inlet design, aircraft nose/wing shaping, ballistic reentry, and wind tunnel nozzle design.
Oblique shock calculations are essential for aerospace engineering but involve transcendental equations that cannot be solved in closed form. This calculator handles the iterative solution automatically.
It is invaluable for students, aerospace engineers, and researchers working with supersonic and hypersonic flows. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain.
tan(θ) = 2·cot(β)·(M₁²sin²β − 1) / (M₁²(γ + cos2β) + 2). M₁ₙ = M₁·sin(β). Normal shock applied to M₁ₙ. p₂/p₁ = 1 + 2γ/(γ+1)·(M₁ₙ² − 1). ρ₂/ρ₁ = (γ+1)M₁ₙ² / ((γ−1)M₁ₙ² + 2). T₂/T₁ = (p₂/p₁)/(ρ₂/ρ₁). M₂ = M₂ₙ/sin(β − θ).
Result: β ≈ 37.8°, M₂ ≈ 1.99, p₂/p₁ ≈ 2.82
For M₁ = 3, θ = 20°: the weak shock solution gives β ≈ 37.8°. M₁ₙ = 3·sin(37.8°) = 1.84. Pressure ratio = 3.78. Downstream Mach after shock = 1.99.
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For a given M₁ and θ, two β solutions exist. The weak shock (smaller β) keeps the flow supersonic downstream. The strong shock (larger β, close to 90°) makes it subsonic. In practice, the weak shock almost always occurs.
When the deflection angle θ exceeds the maximum for the given Mach number. The shock detaches from the surface and becomes a curved bow shock standing upstream of the body.
A special case of an oblique shock with β = 90°. It produces the maximum pressure jump and always makes the downstream flow subsonic.
Shocks are irreversible — they generate entropy. The entropy rise is proportional to the stagnation pressure loss: Δs/R = −ln(p₀₂/p₀₁). Stronger shocks lose more stagnation pressure.
Supersonic inlets use a series of weak oblique shocks to gradually decelerate the flow, followed by a weak normal shock. This reduces total stagnation pressure loss compared to a single normal shock.
Air at moderate temperatures: γ = 1.4. Monatomic gases (He, Ar): γ = 1.667. Diatomic at high temperature (vibration excited): γ ≈ 1.3. CO₂: γ ≈ 1.3.