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According to the "South China Morning Post" report, Chinese scientists published a paper pointing out the reasons for the failure of the United States' continuous hypersonic weapon test launches, and the hypersonic aerodynamic simulation and analysis software led by NASA may have fatal flaws.
American scientists could not have imagined that there was a problem with the Vulcan-CFD software
Hypersonic technology is a technology that many countries around the world are trying their best to break through, and at present, China and Russia have long been equipped with hypersonic missiles, among which Russia's hypersonic missiles have also participated in the Russian-Ukrainian war and destroyed many targets! In addition to China and Russia, North Korea and Iran have also claimed to have mastered the technology of hypersonic missiles, among which North Korea has recently test-fired the "Hwasong-16B" gliding hypersonic missile with a wave-riding body
However, among these hypersonic breakthroughs, there is one less buzzword that appears most frequently: "the United States" The United States began to develop hypersonic weapons earlier than any of the above-mentioned countries, and invested more money and technical strength than any other country, but it has repeatedly failed and failed, and even three consecutive failures still insist on development, this spirit can really be described as persistent, but in the United States, where science and technology are so powerful, a small superb weapon has never been able to do it, and even the Americans do not know what the reason is.
A team led by Professor Liu Jun, a researcher at the Hypersonic Technology Laboratory, published in the Journal of Aerodynamics on March 14, showed that an overlooked fatal flaw in the complex equation of high-temperature ablation used by Americans to study hypersonic simulation and analysis may be the real source of the problem:
In the hypersonic state, the air has been unable to sense the arrival of the aircraft through the compressed airflow, and the compressed airflow will form a sharp shock wave with the shape of the body, which has a large compression wave energy and will produce a very high temperature near the nose cone of the aircraft, so the aircraft often needs to make high-temperature resistant materials in this position to prevent it from being burned by hypersonic pneumatic heating.
But the material in this position is not only high temperature resistance, but also needs to transmit electromagnetic waves or infrared or even visible light, the reason is very simple, the current breakthrough of countries are hypersonic missiles, since it is used as a missile, it must not be made blind, so the nose cone will be loaded with communication antennas, radar, infrared and visible light and other photoelectric detection equipment, so the requirements for this position are perverted.
There are many materials that can transmit waves and light, but most of them are not resistant to high temperatures, so scientists with clever brains have come up with amazing operation methods, such as using "sweating materials" to deal with high-temperature ablation, which is simply to make a lot of evaporating components on the surface of the wave-transmitting material, and evaporation takes away a lot of heat at high temperatures, keeping the nose cone fairing of the warhead and the wave-transmitting material. Of course, it is not only in this way, countries with high material technology, such as China, have made materials that are resistant to high temperature and wave transmission without "sweating", and the structure is simple and saves weight.
But even so, it is necessary to analyze the material erosion at this location under simulated hypersonic conditions to understand the high temperature distribution and diffusion range, and to determine the maximum temperature that can be reached, because under such extreme conditions, both oxygen and nitrogen react and have a great impact on the surface of the shell, so to develop a hypersonic vehicle, a large number of wind tunnel tests are required.
Data typically acquired in hypersonic wind tunnels are analysed using Vulcan-CFD, a set of continuous flow fields that can be simulated from subsonic to hypersonic conditions, using governing equations including chemical and thermal non-equilibrium processes, as well as various turbulence models for Reynolds averaged and large eddy simulations. Finite rate chemical and/or thermodynamic non-equilibrium is allowed. The element-centric solver can handle unstructured meshes with multiple structured or mixed elements (tetrahedral, prismatic, pyramidal, and hexahedral). The software was developed in the hypersonic aspiration propulsion component of NASA's Langley Research Center, and the latest version is 7.2.0, and the software is so influential that it is used for advanced data analysis in most wind tunnels around the world!
However, the team led by Professor Liu Jun, a researcher at the Hypersonic Technology Laboratory, found that Vulcan-CFD has a very serious problem with the detail processing of hypersonic flow fields, and the team said in the paper that the software's lack of attention to this detail makes it impossible for simulation analysis to accurately predict the chemical composition and temperature changes of the aircraft surface, which could have a significant impact on simulation, design or analysis efforts that rely on the aircraft surface.
The simple understanding is that it is impossible to accurately restore the actual environment in which the hypersonic fairing is located, and all the fairings designed for this simulation need have great defects, and some "unreinforced" areas may be washed out by high-temperature airflow more serious than those outside the test, resulting in wave transmission failure and even loss of contact to runaway crashes, etc., failure is inevitable, and success becomes a fluke, so several hypersonic failures of the US military so far prove this.
You should be very curious, since this kind of software has a great impact, why China's hypersonic speed has not been affected at all? The reason may make you laugh faint, because the software has long been blocked by NASA to China technology blockade and is not allowed to be used by Chinese, and the use of the software abroad is strictly restricted, such as only scientific research institutions in the United States can buy and use, of course, such as Europe, America and Japan and other scientific research institutions have a very low threshold, as long as the United States registered an institution or cooperative institution can be used.
However, the result was a slap in the face, and the Chinese came up with their own testing software to avoid this giant pit! And NASA's Vulcan-CFD software because the impact is too great, no one questions its authority, as a result, this tool software because of negligence in processing data caused the United States hypersonic technology to advance only half a step for more than ten years, NASA's jet propulsion laboratory JPL was still led by Qian Xuesen, but now it has been reduced to the level of misguided children, I don't know if Bill Nelson, who sprays Chinese stealing technology every day, will be red and ashamed to death after seeing this news.
The U.S. hypersonic test has failed repeatedly: it is so exaggerated that netizens can't hold back
The United States is closest to the actual combat of the three major hypersonic programs, LRHW and ARRW gliding hypersonic missiles and HAWC air-breathing hypersonic missiles, of which LRHW and ARRW have been test-launched many times, the following are the records of the test launches of these two missiles, the first is LRHW:
- In June 2022, the LRHW missile failed during the CPS weapon test after the assembly was completed, and the missile failed to ignite successfully;
- Three consecutive tests failed in March, September and October 2023, and Breaking Defense also reported that it lost two missiles in two tests in March and September, and that the October test found a failure before ignition, and the test was terminated to save the missile.
LRHW is a high-tech missile project promoted by the U.S. Army and Navy, this missile uses axisymmetric bicone gliding hypersonic warhead, gliding performance is average, but it can solve the problem of whether there is one, as early as 2021, the U.S. Army was equipped with training bombs and was in full swing training, at that time it was thought that the missile was close to being equipped, but after a delay of 3 years, the missile still failed again and again, and the enthusiasm for this training was gone.
The U.S. Navy originally planned to equip the LRHW on the Zumwalt-class destroyers, but with the number of Zum construction plummeting and the budget seriously exceeded, and because the LRHW was far away, the Navy had long lost confidence that the LRHW could be equipped, and now it is close to the door, which may be a success, but it is more likely to be canceled. Another one that has repeatedly failed is ARRW:
- On April 5, 2021, the ARRW missile booster was tested for the first time, but failed to disengage from the B-52's pylons during the test;
- On July 28, 2021, the U.S. Air Force conducted the second test of ARRW's booster, but the booster failed to ignite after release;
- On December 15, 2021, the AGM-183A missile (booster + warhead) was tested, and the missile failed to disengage from the carrier aircraft, and the test failed;
- On May 14, 2022, the U.S. Air Force tested the AGM-183 ARRW hypersonic missile for the fourth time, and successfully ignited after being launched from a B-52 bomber, and finally flew at five times the speed of sound, and the test was a complete success;
- On March 13, 2023, the U.S. Air Force tested the AGM-183 ARRW hypersonic missile for the fifth time, but the data link was interrupted, the missile was missing, and most of the test data may have been lost;
AARW is a hypersonic gliding missile project led by the U.S. Air Force and developed by Lockheed Martin, with a range of 1,600 kilometers and a wave-riding warhead, similar to North Korea's recently unveiled "Hwasong-16B" This is also a project that the Air Force has high hopes for, because of the determination to contain China's determination to solve the Taiwan Strait issue, the B-52 carrying hypersonic missiles taking off from Guam Airport is the biggest threat and the lowest cost, but the repeated failures have seriously discouraged the US Air Force, so it threatened to cancel it in April 2023, but at that time, a number of ARRW missiles had already been produced, and they could only be tested to obtain the most data. However, the subsequent test launches only gave the US Air Force a "valuable new understanding" of the missile:
- On August 19, 2023, the Air Force conducted another test of ARRW and said it had "gained valuable new insights into ARRW's capabilities."
- On October 12, 2023, the Air Force conducted another test of ARRW and said it had "gained valuable new insights into the capabilities of this emerging cutting-edge technology."
- Another test launch was made on December 9, 2023, which, according to the WIKI information, was successful, but according to US media reports, AGM-183A was not successful and is currently to be verified.
The last test launch was on March 24 this year, taking off from Guam and flying about 4,000 kilometers eastward, entering the launch position in the waters southwest of Hawaii, and then the missile was launched to the Reagan missile test site in the southwest of Kwajalein Atoll, simulating a threat to China's southeast coast.
HAWC is an air-breathing hypersonic weapon being developed by the U.S. Air Force, using a transcendental ramjet engine, which may be the fastest advanced weapon in the United States at present, according to WIKI information, HAWC has been successfully tested three times in March 2022, July 18, 2022 and January 30, 2023, the reason may be that the air-breathing hypersonic speed is at 5~Mach 6, the current American Vulcan-CFD test software can be covered, or the error is not large, but the maximum speed of gliding is Mach 10~20, which is very likely to be unable to cover, and eventually lead to failure.
Extended reading: Why tell them?
Regarding this paper, the author is very curious, the Americans have defective software, so let them continue to defect, why tell them? Is this a leak? The author thinks that it should also be regarded as a kind of paper, although the paper does not give specific data, but as NASA has been immersed in the field of hypersonic for decades, many things are just a layer of window paper that will be broken!
So this reminder is likely to bring an innovation to the Vulcan-CFD software, and the version of this software will be upgraded from 7.2.0 to 7.2.1 after a while, which is not a good thing, although the Americans will break through hypersonic technology sooner or later, but one day later is a day, and the Americans will pay the maximum cost of time and capital!