Periodic Pressure Field Measurement Using Pulse Light and Synchronized Camera
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Solution Overview
Problem
Existing pressure measurement systems using pressure sensitive paint face challenges in achieving high-frequency pressure field measurements due to reduced light input and low signal-to-noise ratios, especially when trying to filter out light from the light source, which affects the accuracy of pressure calibration.
Innovation Solution
A periodic pressure field measurement system and method utilizing a pulse light source, CCD camera, and synchronizer, where the camera captures images of pressure sensitive paint under controlled exposure times and light conditions, eliminating the need for filters by using the fluorescence lifetime to enhance signal-to-noise ratios and improve pressure calibration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the exposure time of the camera is shortened to meet high-frequency pressure field measurement requirements, then the measurement frequency is improved, but the light input of the camera decreases, resulting in low signal-to-noise ratio and reducing pressure calibration accuracy
Solution Approach 1:
The patent employs periodic action by using a pulse light source that emits light in periodic pulses synchronized with the camera exposure. This allows the camera to capture fluorescence signals during the pulse duration even with short exposure times, maintaining both high measurement frequency and adequate signal strength for accurate pressure calibration.
Solution Approach 2:
The patent changes the parameter of light delivery from continuous to pulsed mode. By controlling the pulse duration and frequency of the light source to match the camera exposure settings, the system optimizes the light input during the critical exposure window, enabling high-frequency measurements without sacrificing signal-to-noise ratio.
2Object-affected harmful factors
If a filter is used to filter out light from the light source, then the light filtering effect is improved, but the filter has limited filtering capability and cannot completely eliminate light intensity from the light source, resulting in low signal-to-noise ratio
Solution Approach 1:
The patent extracts the harmful light source interference by using temporal separation - the pulse light source emits light only during the camera exposure period, while the camera captures images only during the fluorescence emission window. This time-based extraction eliminates the need for optical filters and completely removes light source interference from the captured images.
Solution Approach 2:
The patent converts the potential harm of light source interference into a benefit by synchronizing the pulse light emission with the camera exposure. The light source pulse duration is carefully controlled to match the exposure window, so that the light source illumination becomes the desired excitation signal rather than interference, enabling complete elimination of harmful effects.
3Speed
If the exposure time is reduced for high-frequency measurement, then the measurement speed is improved, but the light input decreases, affecting the quality of fluorescence images
Solution Approach 1:
The patent uses periodic pulsed illumination synchronized with camera exposure. The pulse light source delivers concentrated light energy during the brief exposure window, maintaining adequate illumination intensity even with reduced exposure times, thus preserving image quality while achieving high measurement speed.
Solution Approach 2:
The system performs preliminary synchronization between the pulse light source and camera exposure timing. By pre-establishing the temporal relationship between light emission and image capture, the system ensures maximum light input during the critical exposure moment, optimizing both speed and quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for high signal-to-noise ratio fluorescence image pairs, reducing system errors and enabling accurate dynamic pressure distribution measurements without the need for light source filtering, thus improving measurement accuracy and range.
Implementation Method 1
the photosensitive molecules in the paint obtain energy from an originally stable ground state so as to be transitioned to a high-energy-level excited state... the light intensity of the pressure sensitive paint can reflect a value of the pressure on the surface of the measured model
Implementation Method 2
The photosensitive molecules in the unstable excited state are impacted by oxygen molecules diffused from the measured surface to lose the energy in the excited state so as to be deactivated to return to the ground state... the higher the concentration of the oxygen molecules, i.e., the higher the pressure in the atmosphere, the stronger the oxygen quenching effect
Data Source
AI summary
Surface pressure measurements on rotating models are important for flow phenomenon identification, understanding flow mechanisms and model aerodynamic design. The disclosure discloses a periodic pressure field measurement system based on the superposed lifetime of pressure sensitive paint, including pressure sensitive paint, a pulse light source, a camera, a synchronizer and a computer. A lifetime superposition method is disclosed in the disclosure for measuring periodic pressure fields of pressure sensitive paint. The disclosure has the beneficial effects: the disclosure acquires, on the basis of a relationship between the fluorescence lifetime of the pressure sensitive paint and the pressure, fluorescence image pair sequence of the pressure sensitive paint with a high signal to noise ratio under a high-frequency pulsating pressure through the strobe light source and the low-frame-rate CCD camera, and obtains the global dynamic pressure distribution according to the measurement principle of the lifetime method, which can effectively reduce system errors.