pyskyfire.regen.channel_height

Functions

make_channel_height_fn(→ Callable[[float], float])

Construct a smooth channel-height profile along a thrust chamber contour.

Module Contents

pyskyfire.regen.channel_height.make_channel_height_fn(contour: Contour, region_fractions: Sequence[float], flat_heights: Sequence[float], pinch_factors: Sequence[float], transition_widths: float | Sequence[float], logistic_k: float = 10.0) → Callable[[float], float]

Construct a smooth channel-height profile along a thrust chamber contour.

Builds a continuous, piecewise-logistic blend of per-region channel heights across the chamber and nozzle. Each region is defined by a normalized axial coordinate fraction relative to the throat, and can optionally “pinch” channel height with radius.

The returned function evaluates the local channel height at any axial coordinate x along the contour.

Parameters:
contourContour

Thrust-chamber contour defining the wall coordinates x and r(x).

region_fractionsSequence[float]

Normalized axial coordinates marking region boundaries:

  • -1.0 → chamber inlet

  • 0.0 → throat

  • +1.0 → nozzle exit

flat_heightsSequence[float]

Base (unpinched) channel heights for each region [m].

pinch_factorsSequence[float]

Fraction in [0, 1] describing how strongly each region’s height scales with local radius. 0 means constant height, 1 means fully proportional to radius.

transition_widthsfloat or Sequence[float]

Axial transition width(s) controlling how quickly heights blend between adjacent regions. If a single scalar is given, it is used for all boundaries.

logistic_kfloat, optional

Steepness of the logistic blending function. Higher values yield sharper transitions. Default is 10.0.

Returns:
Callable[[float], float]

A callable function channel_height(x) that returns the local channel height [m] at axial coordinate x.

Raises:
ValueError

If the number of transition widths does not match len(flat_heights) - 1.

Notes

The normalized coordinate mapping is:

  • Negative region fractions → chamber side

  • Positive region fractions → nozzle side

Transitions are blended smoothly using a logistic weighting function centered at each region boundary. Channel heights can pinch with radius according to pinch_factors.

Examples

>>> channel_height_fn = psf.regen.make_channel_height_fn(
            contour=contour,
            region_fractions=[-1.0, 0.25, 1.0],
            flat_heights= [0.0032, 0.00134],
            pinch_factors= [0.6, -5.0],
            transition_widths=[0.1]
>>> fn(0.12)  # Evaluate channel height at some axial x
0.0034