Method and system for diagnosing high-enthalpy shock tunnel parameters

A method for diagnosing high-enthalpy shock tunnel flow field parameters, comprising:

• step 1, installing a plurality of piezoelectric sensors on a shock tube and a total pressure sensor at an end of the shock tube;
• installing a non-contact absorption spectrum system together with a collimator and a detector of an emission spectrum system near the total pressure sensor at the end of the shock tube, and installing the non-contact absorption spectrum system together with another collimator and another detector of the emission spectrum system in a test section;
• installing a pitot pressure probe, a static pressure probe, and a stagnation point heat flow probe on a bracket in the test section to measure pitot pressure, static pressure, and stagnation point heat flow in a flow field of the test section;
• and sending the data measured by the non-contact absorption spectrum system, the emission spectrum system, the pitot pressure probe, the static pressure probe, and the stagnation point heat flow probe to a first data processing system and a second data processing system (10) via optical fibers or data lines for data processing;
• step 2, measuring a time interval Δt for an incident shock wave passing through the piezoelectric sensors by using the piezoelectric sensors arranged on an upper wall of the shock tube, and calculating a velocity V of the incident shock wave by V=ΔL/Δt based on a distance ΔL between the piezoelectric sensors;
• step 3, measuring, by using the total pressure sensor arranged on a wall of the end of the shock tube, a total pressure P0 in a reservoir at the end of shock tube after the incident shock wave is reflected;
• step 4, measuring translational temperatures and NO and O component concentrations of gas in the reservoir at the end of the shock tube and free flow gas in a high-enthalpy nozzle by using the non-contact absorption spectrum system;
• step 5, measuring vibrational temperatures and component spectral information of the gas in the reservoir at the end of the shock tube and the free flow gas in the nozzle by using the emission spectrum system;
• step 6, installing a sphere on the cross bracket in the test section, and measuring a structure of the flow field around the sphere by using a laser schlieren system, to obtain a shock detached distance at a head of the sphere;
• step 7, obtaining the pitot pressure, the static pressure and the stagnation point heat flow of the flow field by the pitot pressure probe, the static pressure probe and the stagnation point heat flow probe;
• step 8, calculating parameters of the reservoir at the end of the shock tube under high temperature condition based on the velocity V of the incident shock wave measured in the step 2, the total pressure P0 in the reservoir at the end of the shock tube measured in the step 3, a thermodynamic numerical model of high temperature air and quasi-one-dimensional shock tube theory;
• comparing the parameters of the reservoir at the end of the shock tube with the temperature and NO AND O component concentration in the reservoir at the end of the shock tube measured in the step 4;
• if a difference between two data is greater than a predetermined threshold a, modifying the thermodynamic numerical model and performing iteration until the difference between the two data is equal to or less than the predetermined threshold a;
• step 9, calculating initial condition of a flow field in the high-enthalpy nozzle by taking the parameters of the reservoir at the end of the shock tube obtained after the iteration in the step 8 as input, calculating the flow field of the high-enthalpy nozzle by using a multi-component and multi-temperature thermochemical non-equilibrium numerical simulation method to obtain outlet parameters at the high-enthalpy nozzle, and comparing the outlet parameters at the high-enthalpy nozzle with the measured data in steps 3 to 7;
• if a difference between two data is greater than predetermined threshold b, modifying the numerical model and performing iteration until the difference between the two data is equal to or less than the predetermined threshold b.