Application Cases

Experiment Name: Dynamic Characteristic Testing and Calibration Experiment of Circular Foil Heat Flux Sensors (Gardon Gauges) Based on Laser Method

Experiment Principle: The Gardon gauge is regarded as a first-order system due to its thermal inertia. For step response, the time constant is the time required for the heat flux difference to reach 63.2% of the difference between the final steady-state value and the initial value. For pulse response, the time constant is the time for the heat flux difference to drop to 36.8% of the difference between the maximum value and the initial value. The heat flux is linearly related to the laser parameters. Under step excitation, the laser power is positively correlated with the steady-state heat flux, influenced by the coating absorptivity and the heated area of the sensor. Under pulse excitation, both the laser power and pulse width are positively correlated with the heat flux; together they determine the pulse energy, with higher energy resulting in greater heat flux. Additionally, the thermal diffusivity of constantan material increases slightly with temperature and is inversely proportional to the time constant, which can lead to a decrease in the sensor's time constant as the heat flux increases.

Experimental Block Diagram:

Experimental Setup Photos:

Experimental Procedure:

1. A dynamic heat flux calibration platform was constructed. The core components included modules for laser generation, signal modulation (waveform generator + broadband amplifier), beam shaping, signal conditioning, data acquisition (oscilloscope), and water cooling, ensuring stable experimental operation.

2. The laser beam was tested and verified: Continuous laser testing confirmed its intensity stability, and pulse laser testing verified the linear relationship between power, pulse width, and output energy. The rise time of the pulsed laser was also measured to ensure that the laser signal did not affect the experimental results.

3. Dynamic testing experiments were conducted: In step response experiments, different laser powers were adjusted to analyze their relationship with the sensor's steady-state heat flux and time constant. In pulse response experiments, various combinations of laser power and pulse width were used to investigate the correlation between these parameters and heat flux and time constant, identifying the ideal pulse excitation conditions.

Product Recommendation: ATA-1000 Series Broadband Amplifier

Figure: ATA-1000 Series Broadband Amplifier Specifications and Parameters

This document is compiled and published by Aigtek Antai Electronics. For more case studies and product details, please stay tuned. Xi’an Aigtek Antai Electronics has become a large-scale instrument and equipment supplier with a wide range of products in the industry. Demo units are available for free trial.