System and method for using pressure-sensitive paint (PSP) to analyze unsteady aerodynamic loads on vehicles

An apparatus for measuring and computing unsteady loads using unsteady pressure-sensitive paint (uPSP) data, the apparatus comprising:

• at least one processor;
• and
• memory comprising a set of instructions, wherein
• the at least one processor, when executed by the set of instructions, are configured to perform
• in-situ calibrating using an average of pixels of an image captured of a surface painted with pressure-sensitive paint
• dividing an average static pressure by an intensity for each region of interest (ROI) in the image in terms of time to produce a ratioed intensity measuring an intensity fluctuation;
• and
• producing a pressure-time history from the in-situ calibration and the measured intensity fluctuation;
• calculating a fluctuating force by multiplying the produced pressure-time history by an area of pixels in each ROI;
• converting a time signal to a frequency;
• producing a power spectral density (PSD) to compare frequency content to determine an amount of energy at a certain frequency band;
• and
• calculating an intensity time history for each ROI,
• wherein the calculating of the intensity time history for each ROI is performed by
• I
• ⁡
• (
• t
• )
• =
• ∑
• p
• =
• 1
• m
• I
• p
• (
• ROI
• q
• )
• where I is an intensity in relation to time t, q is a region of interest number, p is a pixel number, and m is total number of pixels averaged.

A method for measuring and computing unsteady loads using unsteady pressure-sensitive paint (uPSP) data, comprising:

• calculating, by a computing system, an average of pixels in space and time of a portion of an image captured of a surface painted with pressure-sensitive paint at a location near a static tap;
• performing, by a computing system, an in-situ calibration using the average of pixels of the portion of the image;
• dividing, by the computing system, an average static pressure by an intensity for each region of interest (ROI) in the image in terms of time to produce a ratioed intensity measuring an intensity fluctuation;
• and
• producing, by the computing system, a pressure-time history from the in-situ calibration and the measured intensity fluctuation;
• calculating, by the computing system, a fluctuating force by multiplying the produced pressure-time history by an area of pixels in each ROI;
• converting, by the computing system, a time signal to a frequency;
• producing a power spectral density (PSD) to compare frequency content to determine an amount of energy at a certain frequency band;
• calculating an intensity time history for each ROI,
• wherein the calculating of the intensity time history for each ROI is performed by
• I
• ⁡
• (
• t
• )
• =
• ∑
• p
• =
• 1
• m
• I
• p
• (
• ROI
• q
• )
• where I is an intensity in relation to time t, q is a region of interest number, p is a pixel number, and m is total number of pixels averaged.