Engineering a conformal optical window of a square-to-circular transition isolator

Area of Science:

• Aerodynamics
• Optical Engineering

Background:

• Shock train structures in square-to-circular transition isolators are critical for aerodynamic performance.
• Accurate flow visualization is essential for understanding these complex phenomena.
• Existing methods face challenges in achieving high-fidelity measurements within these isolators.

Purpose of the Study:

• To develop and validate a high-precision conformal optical window for Schlieren measurements.
• To enable detailed flow visualization of shock train structures in a square-to-circular transition isolator.
• To improve the accuracy and reliability of aerodynamic measurements in complex geometries.

Main Methods:

• Manufacturing a high-precision conformal optical window using fly-cutting technology.
• Optimizing the window's outer surface based on super-elliptic curves and light refraction principles.
• Conducting Schlieren measurements using a Z-type apparatus and applying image filtering techniques.

Main Results:

• Achieved a transmitted wavefront error (RMS value) of 0.823λ (λ=632.8 nm) for the optical window.
• Successfully performed high-precision Schlieren measurements through the manufactured window.
• Obtained detailed visualizations of shock train structures within the transition isolator.

Conclusions:

• The developed high-precision optical window is effective for Schlieren measurements in square-to-circular transition isolators.
• This advancement facilitates more accurate studies of shock train phenomena.
• The methodology promotes enhanced Schlieren observation capabilities for complex aerodynamic flows.