Navronis v0.4.0 — Day 4: Supersonic Nozzle Aerodynamics & Altitude Engine

Navronis v0.4.0 — Day 4: Supersonic Nozzle Aerodynamics & Altitude Performance

We are thrilled to announce the Day 4 Public Release of Navronis (v0.4.0), expanding the liquid rocket propulsion preliminary sizing pipeline to high-speed exhaust expansion, supersonic contour generation, and trajectory altitude performance.

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What's New in Day 4 (v0.4.0):

1. 1D Isentropic Area-Mach Supersonic Inversion (NASA SP-125):

   • High-precision root solver mapping geometric nozzle area ratio $\varepsilon = A_e / A_t$ to supersonic exit Mach number $M_e$.
   • Static pressure ($P_e$), static temperature ($T_e$), and sonic exit velocity ($v_e$) across any arbitrary combustion gas combination.

2. Rao (1958) 80% Parabolic Bell Contour:

   • Quadratic Bézier parabolic spline connecting the circular throat arc ($ heta_n �pprox 30^\circ$) to a shallow exit lip angle ($ heta_e �pprox 8^\circ$).
   • Yields over 1% higher delivered thrust coefficient than a standard 15° cone of equivalent length.

3. 2D Divergence Loss Factor ($\lambda$):

   • Exact analytical model for conical nozzles $\lambda = (1 + \cos\alpha)/2$ and Rao parabolic bells using the mean-angle formulation.

4. Turbulent Boundary Layer Displacement ($\delta^*$):

   • Schlichting (1979) 1/7th-power turbulent boundary layer displacement thickness $\delta^* = \delta / 8$ and flow area blockage correction.

5. Stark (2005) Tri-Criteria Flow Separation Screening:

   • Evaluates Summerfield (1954), Schmucker (1973), and Kalt & Badal (1965) simultaneously.
   • Preserves rigorous physics closure: returns CONFLICT_UNRESOLVED when empirical models contradict rather than arbitrarily selecting a winner.

6. 1976 U.S. Standard Atmosphere Trajectory Solver:

   • Barometric altitude marching from sea level ($z = 0$) through the stratosphere ($z = 86\text{ km}$), computing ambient pressure, density, and delivered $I_{sp}(z)$.

7. Merged PR #9 from @tenten48tenten (Closes #1):

   • Contraction ratio bounds audit, Huzel-Huang Eq. 4-5 analytical closed-form equivalence, and supercritical Bartz property monotonicity.

8. Live Interactive Web App Update:

   • Dynamic SVG CAD rendering now visualizes the full supersonic nozzle bell contour to scale, with live altitude sliders and shock separation warning indicators.

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Verification:

• 62 / 62 Unit Tests Passing (100% pass rate in 3.15s).
• Full provenance transparency via .explain() on every computed parameter.