How scientists analyzed the aerodynamic features of the Tianwen-1 Mars parachute

China’s Tianwen-1 Mars probe correctly landed on the Utopia Basic at 7:18 a.m. Beijing Time, on 15 May well 2021. The good results charge of Mars missions is about 50%, and most failures take place through the entry, descent, and landing (EDL) stage. Parachutes of very low-density supersonic engage in a very important purpose in the EDL of Mars and straight figure out the achievement of the entire mission. In a investigation paper not too long ago published in House: Science & Technological innovation, Mingxing Huang from Beijing Institute of Space Mechanics and Electrical energy carried out the design, growth, and qualification of the Tianwen-1 Mars parachute, which can offer a reference for the development of future Mars exploration parachutes.

The writer to start with concentrated on the evaluation and collection of Mars parachute kinds. In comparison with the parachutes that get the job done on Earth, the parachutes of the Mars lander face much more troubles. On just one hand, the open flight of the Mars parachute is characterised by supersonic velocity, low density and minimal dynamic stress. On the other hand, atmospheric things to do, these types of as Martian vortex activity and dust storms, may well lead to severe parachute opening problems. Thus, issues in opening the parachute, unstable inflation, and lessened drag coefficient should be considered in the style of parachute.

All the foreign landers efficiently reached tender landing on Mars have used the DGB (Disk-Gap-Band) parachute, which has good security and exceptional inflation performance in the supersonic and low-density operating natural environment. Owing to its demonstrated large-altitude functionality and lower complex hazard, the DGB parachute with improved layout modifications is picked as the candidate for the Tianwen-1 Mars probe. In accordance to the ratio of the band area to the complete cover, the DGB parachutes can be divided into the Viking form and the MPF (Mars Pathfinder) sort.

The Viking type DGB parachute has a large drag coefficient and weak stability, while the MPF and its enhanced DGB parachute have a scaled-down drag coefficient but better security. Moreover, two strategies ended up adopted to improve and improve the current DGB parachute construction. 1 is to raise the drag coefficient. The disk part is therefore modified to a construction with a greater drag coefficient The other is to enlarge the band’s location to increase the parachute’s security, this kind of as including a tapered band on the skirt of the cover. As a result, five DGB parachute constructions, together with the MPF, Viking, hemisflo, triconical and tapered construction, had been picked as candidates.

Later on, to enhance the construction for the Mars parachute, the subsonic, transonic, and supersonic wind tunnel tests had been carried out for the 5 DGB parachutes to obtain their drag coefficients and oscillation angles. Merged with the wind tunnel take a look at outcomes at different Mach figures to pick out a parachute with much better deceleration and steadiness general performance, the tapered DGB parachute ended up the finest deceleration parachute for the Tianwen-1.

Finally, to demonstrate the functionality of whole scale tapered DGB parachutes in Mars flight problems, four significant-altitude flight tests were carried out by sounding rockets in April 2018. In the course of the flight, the 1st phase burned out at altitudes of somewhere around 17km~20 km, respectively, the payload portion achieved apogee amongst 49km and 64 km. When the payload acquired the focus on dynamic strain and Mach selection, the parachute was mortar-deployed.

The deployment, inflation, and supersonic and subsonic aerodynamics of the parachute had been analyzed by a suite of devices, which includes a superior-velocity video method trained on the parachute, a established of load pins at the interface of the parachute bridles and the payload, and a GPS and inertial measurement device (IMU) onboard the payload. Right after decelerating to subsonic pace, the parachute and payload descended to the take a look at variety for restoration. All the tests focused a precise dynamic pressure at parachute deployment to arrive at a wished-for load on the parachute at comprehensive inflation.

The parachutes had been mortar-fire deployed at dynamic pressures ranging from 100Pa to 950Pa and Mach numbers amongst 2.05 and 2.35. In comparison, the parachute of Tianwen-1 ought to be in a position to get opened reliably in just the selection of Ma1.6~Ma2.3 and dynamic tension array of 250Pa~850Pa. Underneath the superior-altitude opening check carried out on the Earth and the precise functioning circumstances of Mars, the Reynolds figures are both equally in the buy of 2×10⁶. The test benefits reveal that the drag coefficient of the tapered DGB parachute assorted from .39 to .70 with the Mach selection amplified from Ma .2-Ma 2.4 and arrived at the maximum value of .7 at Ma 1.5 the utmost AOA immediately after parachute deployment is about 20°, which have all shown that the general performance of the tapered DGB parachute could meet up with the deceleration requirements of the Tianwen-1 Mars probe.

Offered by
Beijing Institute of Engineering Push