Aerospace & Aeronautical Engineering / Prandtl-Meyer Expansion Fan
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LABORATORY 14 · AEROSPACE & AERONAUTICAL ENGINEERING

Prandtl-Meyer Centered Expansion Waves and Convex Corner Flow

Map Mach number increase and static pressure drop across a sharp convex expansion corner to evaluate the Prandtl-Meyer function nu(M). Explore interactive wind tunnel simulation, flight dynamics, and aerospace engineering telemetry.

AERODYNAMICS · PROPULSION · FLIGHT DYNAMICS

Your virtual aerospace engineering laboratory.

MACH INCREMENT DELTA M—
FLIGHT & TEST CELL TELEMETRY

Ready to sample with theta = 6.0 deg.

6.0 deg
Upstream Mach number M_1: 1.80

Adjust theta, then execute aerospace trial.

Aeronautical telemetry and flight states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity aerodynamic modeling.

Aeronautical assumptions and boundary condition limits

Convex corner curvature creates a localized boundary layer thinning and favorable pressure gradient that can laminarize turbulent flow. Linear regression of the Mach increment against convex turn angle yields an expansion gradient of 0.0520 deg^-1 with R^2 > 0.999999.

Aeronautical apparatus & wind tunnel sensors.

Supersonic Corner Expansion Test Duct

Optical supersonic channel with interchangeable convex corner blocks from theta = 3.0 to 18.0 degrees.

Supersonic Blowdown Air Supply

Delivers dry, heated air at stable stagnation pressure P_0 = 350 kPa and M_1 = 1.80.

Downstream Static Pressure Tap Array

Precision static taps spaced 5 mm apart along the expanded wall downstream of the corner apex.

Multi-Channel Electronic Manometer Scanner

Samples wall static pressures P_2 with 16-bit A/D resolution and temperature compensation.

Toepler Schlieren Optical System

Visualizes the leading Mach wave, centered fan rays, and trailing Mach wave of the expansion fan.

Prandtl-Meyer Data Processing Workstation

Converts static-to-total pressure ratios into local Mach numbers and evaluates the nu(M) function.

FOLLOW THE METHOD

A reason behind every step.

Map Mach number increase and static pressure drop across a sharp convex expansion corner to evaluate the Prandtl-Meyer function nu(M). Standardized parameter settings: 3.0, 6.0, 9.0, 12.0, 15.0, 18.0 deg.

01

Corner Model Alignment

Install the theta = 3.0 degree convex corner model into the optical test section, aligning the upstream floor with the nozzle exit.

02

Schlieren Wave Verification

Initiate supersonic blowdown at M_1 = 1.80, verifying through Schlieren optics that the leading expansion wave is inclined at mu_1 = arcsin(1/1.80) = 33.75 deg.

03

Upstream Baseline Acquisition

Record upstream reference static pressure P_1 and stagnation pressure P_01 ahead of the expansion corner.

04

Downstream Pressure Mapping

Acquire downstream wall static pressures P_2 at fully expanded stations for convex angles theta = 3.0, 6.0, 9.0, 12.0, 15.0, and 18.0 degrees.

05

Mach Number Computation

Compute downstream Mach number M_2 using the isentropic relation: M_2 = sqrt(5 * [(P_01/P_2)^(2/7) - 1]) and compute Delta M = M_2 - M_1.

06

Prandtl-Meyer Linear Regression

Plot Delta M versus theta, perform linear regression to determine the expansion rate dM / dtheta, and compare with the theoretical Prandtl-Meyer derivative.

YOUR NOTEBOOK · 0 OBSERVATIONS

Turn measurements into aerodynamic insight.

See a complete example report ↗

Points are your recorded observations. The solid regression line validates Prandtl-Meyer Expansion Fan mathematical scaling.

LINEAR REGRESSION FIT · y = mx + b
\Delta M = (M_2 - M_1) \approx m \cdot \theta_{\text{deg}} + b
#Convex Turn Angle theta (deg)Mach Increment Delta M (dimensionless)Convex Wall Turn Angle theta (deg)Downstream Mach Increment Delta M = M_2 - M_1Remove

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Calculate it yourself.

CHECK YOUR UNDERSTANDING

Explain what the aerodynamic metrics mean.

What happens to the total stagnation pressure P_0 across an ideal Prandtl-Meyer expansion fan?

How does flow velocity change as a supersonic stream navigates a convex expansion corner?

What is the orientation of the leading wave of a centered expansion fan relative to the upstream wall?

For initial Mach M_1 = 1.80 and a turn of theta = 6 degrees, what is the approximate downstream Mach increment for dM/dtheta = 0.052 deg^-1?