Two concepts have been adopted to optimize and enhance the prevailing DGB parachute construction. One is to extend the drag coefficient. The disk half is thus modified to a construction with a better drag coefficient, such because the hemisflo parachute construction and the triconical parachute construction. The opposite is to enlarge the band’s space to extend the parachute’s stability, comparable to including a tapered band on the decrease skirt of the cover. The precise parachute constructions are proven within the Determine. Credit score: House: Science & Know-how
Find out how to cope with the design, improvement, and qualification of the Tianwen-1 Mars parachute.
China’s Tianwen-1 Mars probe efficiently landed on the Utopia Plain at 7:18 a.m. Beijing Time, on Might 15, 2021. The success fee of Mars missions is about 50%, and most failures happen throughout the entry, descent, and touchdown (EDL) section. Parachutes of low-density supersonic play an important position within the EDL of Mars and immediately decide the success of all the mission. In a analysis paper lately revealed in House: Science & Know-how, Mingxing Huang from Beijing Institute of House Mechanics and Electrical energy carried out the design, improvement, and qualification of the Tianwen-1 Mars parachute, which may present a reference for the creation of future Mars exploration parachutes.
The writer first targeted on the evaluation and choice of Mars parachute sorts. In contrast with the parachutes that work on Earth, the parachutes of the Mars lander face extra issues. On one hand, the open flight of the Mars parachute is characterised by supersonic pace, low density, and low dynamic stress. Then again, atmospheric actions, comparable to Martian vortex exercise and dirt storms, could result in harsh parachute opening situations. Subsequently, difficulties in opening the parachute, unstable inflation, and diminished drag coefficient must be thought of within the design of parachute.
The entire different landers which have efficiently achieved gentle touchdown on Mars have used the DGB (Disk-Hole-Band) parachute, which has good stability and wonderful inflation efficiency within the supersonic and low-density working surroundings. On account of its demonstrated high-altitude efficiency and decrease technical threat, the DGB parachute with improved design modifications is chosen because the candidate for the Tianwen-1 Mars probe. In line with the ratio of the band space to all the cover, the DGB parachutes could be divided into the Viking kind and the MPF (Mars Pathfinder) kind. The Viking kind DGB parachute has a excessive drag coefficient and weak stability, whereas the MPF and its improved DGB parachute have a smaller drag coefficient however higher stability. Moreover, two concepts have been adopted to optimize and enhance the prevailing DGB parachute construction. One is to extend the drag coefficient. The disk half is thus modified to a construction with a better drag coefficient The opposite is to enlarge the band’s space to extend the parachute’s stability, comparable to including a tapered band on the skirt of the cover. Thus, 5 DGB parachute constructions, together with the MPF, Viking, hemisflo, triconical and tapered construction, have been chosen as candidates.
Entry, Descent, and Touchdown sequence of Tianwen-1 lander and Zhurong rover. Credit score: Huang Xiangyu et al. DOI: https://doi.org/10.34133/2021/9846185
Afterward, to optimize the construction for the Mars parachute, the subsonic, transonic, and supersonic wind tunnel exams have been carried out for the 5 DGB parachutes to acquire their drag coefficients and oscillation angles. Mixed with the wind tunnel check outcomes at totally different Mach numbers to pick a parachute with higher deceleration and stability efficiency, the tapered DGB parachute have been the most effective deceleration parachute for the Tianwen-1.
Lastly, to show the aptitude of full scale tapered DGB parachutes in Mars flight situations, 4 high-altitude flight exams have been carried out by sounding rockets in April 2018. Throughout the flight, the primary stage burned out at altitudes of roughly 17km~20 km, respectively, the payload part reached apogee between 49km and 64 km. When the payload received the goal dynamic stress and Mach quantity, the parachute was mortar-deployed.
The deployment, inflation, and supersonic and subsonic aerodynamics of the parachute have been analyzed by a collection of devices, together with a high-speed video system skilled on the parachute, a set of load pins on the interface of the parachute bridles and the payload, and a GPS and inertial measurement unit (IMU) onboard the payload. After decelerating to subsonic pace, the parachute and payload descended to the check vary for restoration.
The entire exams focused a particular dynamic stress at parachute deployment to succeed in a desired load on the parachute at full inflation. The parachutes have been mortar-fire deployed at dynamic pressures starting from 100Pa to 950Pa and Mach numbers between 2.05 and a pair of.35. Compared, the parachute of Tianwen-1 should be capable to get opened reliably inside the vary of Ma1.6~Ma2.3 and dynamic stress vary of 250Pa~850Pa. Underneath the high-altitude opening check performed on the earth and the precise working situations of Mars, the Reynolds numbers are each within the order of two×106.
The check outcomes point out that the drag coefficient of the tapered DGB parachute diversified from 0.39 to 0.70 with the Mach quantity elevated from Ma 0.2-Ma 2.4 and reached the utmost worth of 0.7 at Ma 1.5; the utmost AOA after parachute deployment is about 20°, which have all demonstrated that the efficiency of the tapered DGB parachute may meet the deceleration necessities of the Tianwen-1 Mars probe.
Reference: “Evaluation and Verification of Aerodynamic Traits of Tianwen-1 Mars Parachute” by Mingxing Huang, Wenqiang Wang and Jian Li, 20 March 2022, House: Science & Know-how.
DOI: 10.34133/2022/9805457
Funding: Beijing Institute of House Mechanics & Electrical energy
Post a Comment