Kinetic Energy Measurement of a 1kW Arcjet by Pitot Probe and Laser Absorption Spectroscopy

Transcription

1 26th AIAA Aerodynamic Measurement echnology and Ground esting Conference<BR> June 2008, Seattle, Washington AIAA Kinetic Energy Measurement of a 1kW Arcjet by Pitot Probe and Laser Absorption Spectroscopy S. Nomura (he university of okyo) A. Diallo (he university of okyo) M. Matsui (he university of okyo) H. akayanagi (he university of okyo) G. Herdrich (Stuttgart University) K. Komurasaki (he university of okyo) Y. Arakawa (he university of okyo) Copyright 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

2 Background Diagnostics of the high enthalpy flow Laser Absorption Spectroscopy (LAS) Estimation of specific enthalpy h 0 C ref p d h chem 1 2 V 2 hermochemical equilibrium calculation Assumption; Frozen flow at nozzle expansion Arcjet Recombination is not considered Validation by experiment

3 Estimation of γ γ is also estimated on the assumption of the frozen flow 1 0 ref C p d h chem at the plenum ref C p d 1 2 V 2 h at the plume chem chemical potential is canceled 2 0 ref C p d ref C p d 1 2 V 2 measured total temperature is obtained 3 0 R, frozen flow

4 Specific heat ratio For example Ar:O 2 = 4:1 Plenum pressure; 0.55atm otal temperature; 4000K Frozen flow γ=1.64 Full recombination γ=1.52 γ Frozen flow Experimental value Full recombination o validate γ estimated by equilibrium calculation, it is necessary to estimate γ at the precision of less than±0.01 by experiments. Mach number measurement

5 Mach Probe Mach Probe M 1 sin Estimated error of Mach number

6 Pitot Probe Mach number over p pitot /p static for various γ Estimated error of Mach number (γ=5/3) Pitot probe is more feasible for the measurement of Mach number than Mach Probe

7 Objectives Estimation of γ by comparison of Pitot probe measurement and LAS measurement Experimental validation of γ estimated by equilibrium calculation Validation of the assumption of frozen flow at the nozzle expansion

8 Arcjet Schematic of Arcjet Parameters Values hroat diameter, mm 2 Nozzle diameter, mm 30 input power, kw 1.2(35A) thermal efficiency 0.39 argon flow rate, slm 4 Working gas is pure argon. Specific heat ratio should be 5/3.

9 Pitot probe measurement 6 Appearance of pitot probe measurement Schematic of pitot probe Miniature pitot probe; Bore diameter 2mm Assumption p static =p ambient =34Pa

10 Pitot probe results Radial distribution of pressure ratio(x=43mm) Radial distribution of Mach number(x=43mm,γ=5/3) At the center of the plume, M =2.17 ±0.03

11 LAS Results Velocity distribution (x=43mm) arget line; Argon nm (4s 2 [1/2] 4p 2 [1/2]) At the center value error 5% emperature distribution (x=43mm) Velocity 1870±90 m/s emperature 2244±60 K 3%

12 Mach Number At the center value error M pitot 2.17±0.03 1% M LAS 2.11±0.1 5% Good agreement between Pitot probe and LAS Mach number by the probe is averagely 7% higher than Mach number by LAS.

13 Estimation of γ γ=5/3 At the center of the plume, γ=1.30, M LAS /M Pitot =1±0.06. he deviation is too large to estimate γ.

14 Precision improvement of the γ estimation In order to estimate γ at the precision of 2 decimal digits, the deviation of M LAS /M pitot should be less than ± (Now ±0.06) More accurate measurement is needed. 6% 0.1% M pitot M LAS error 1% 5% Improvement of LAS measurement accuracy

15 Accuracy of LAS Accuracy of LAS Error of temperature D D D FSP 2 ) ( 2 k k ) / )ln( / ( ) / ( I I I I I I k k

16 Ar-O 2 Flow Parameters hroat diameter, mm 2 Nozzle diameter, mm 30 input power, kw gas flow rate, slm Values 0.70(35A) Ar;4 O 2 ;1 γ=1.54 LAS M=4.03±0.03 Pitot probe M=3.27±0.002 γ; Can t be estimated

17 Conclusion Good agreement between Pitot probe and LAS on the condition of pure argon. M LAS is averagely 7% higher than M pitot. he measurement error should be one order of magnitude smaller than now. It is not able to estimate γ on the condition of argon and oxygen. In order to estimate γ, to correct the pitot pressure would be necessary.

18 Stability

19 (Background) Aerodynamic heating at the planetary entry Earth (N 2, O 2 ) Space plane Sample return mission JAXA Re-entry image of HOPE-X Development of hermal Protection System (PS) Simulation of the entry condition on the ground High enthalpy wind tunnel Arc-heater wind tunnel

20 γ- Plenum pressure 0.55atm Ar:O 2 4:1