航空和空间技术周刊： 中国研制高超音速冲压发动鸡

China Developing Scramjet Propulsion

Sep 2, 2007
By Craig Covault


China is starting to ramp up its scramjet propulsion work—an initiative that will benefit high-speed missile programs while also helping the country to develop advanced aerospace materials, greater computational capabilities and a cadre of young engineers who have matured as a result of cutting-edge engine and aerodynamic challenges.

Building on its ramjet experience, China is embracing the much more difficult task of developing Mach 5 air vehicle concepts in which propulsion and aerodynamics are highly coupled.

As part of this effort, an integrated scramjet model is about to begin testing at up to Mach 5.6 in a new wind tunnel in Beijing.

In addition to the technology and engineering experience to be gained, the mid-term military payoff is likely to be more advanced high-speed tactical and medium-range Chinese missiles, especially for antiship warfare that could threaten U.S. aircraft carriers in the Pacific or operating in support of Taiwan.

“China has the greatest potential to compete militarily with the U.S. and field disruptive military technologies that could, over time, offset traditional U.S. military advantages,” the 2006 Pentagon Quadrennial Review said about overall Chinese military technology initiatives.

And over the next several decades, the scramjet work could eventually provide China with a tactical hypersonic global-strike capability beyond the country’s strategic ballistic missile force. The U.S. has similar goals for its own growing scramjet program.

The Chinese allowed a peek into multiple aspects of their scramjet efforts at the recent American Institute of Aeronautics and Astronautics Joint Propulsion Conference in Cincinnati. Chinese engineers from several research facilities presented about a dozen papers on their scramjet developments, as well as details on the new wind tunnel.

At the same forum, their papers revealed new rocket propulsion research, including work on hybrid systems that use a combination of propellants easier to handle and store than most propellants in wider use today. New insight also was offered on Chinese solid rocket motor technology work, important for both missile and space launch applications.

The Cincinnati meeting differed from a traditional U.S. industry gathering, because nearly a dozen engineers from Iran also submitted papers on Iranian solid and liquid rocket technologies. The Iranian engineers are based at the Sharif University of Technology and the KNT Technical University, both in Tehran. They apparently did not deliver the papers in person. However, as participants, the Iranians have access to all of the highly detailed U.S. aircraft and rocket propulsion presentations made at the conference.

A scramjet (supersonic combustion ramjet) flies at Mach 5 or faster using hydrogen fuel and oxygen out of the air for oxidizer. The engine must combine an advanced ramjet that changes configuration to swallow supersonic flow above about Mach 4.

Advanced ramjet technologies are also important for scramjet development, and the Chinese have been active in this area for decades.

Ironically, one the more interesting historical papers presented at the forum was a detailed description of how the U.S. Air Force and Lockheed combined top-secret ramjet propulsion technologies with segmented solid rocket boosters for the Mach 3 D-21B reconnaissance drones that were launched by modified SR-71s and B-52Hs in the late 1960s (see center photo). The D-21B was specifically developed to gather intelligence over China.

This was the first time details on the segmented rocket booster portion of the D-21B program have been presented publicly, says Robert Geisler of Geisler Industries, who led the analysis with retired Pratt & Whitney and ATK Tactical Propulsion engineers. Segmented boosters use individual circular sections like space shuttle solid rocket motors.

China already has such segmented solid rocket motor and ramjet capabilities today, but scramjets are a much greater challenge.

Although nowhere nearly as advanced as U.S. scramjet work, Chinese activities in this discipline will give the Defense Dept. additional impetus to argue for strong, ongoing U.S. hypersonic propulsion funding. Diverse U.S. technology programs are already underway to support development of the X-51 scramjet test vehicle (AW&ST July 23, p. 23).

As part of the Chinese effort, the engineers say new analytical centers are also being developed. For example, a Hypersonic Propulsion Test Facility has been built to support the scramjet program, according to Xinyu Chang, a senior researcher at the Laboratory of High-Temperature Gas Dynamics in Beijing, where the HPTF is located. Gas Dynamics lab research is specifically oriented to “the development of hypersonic flight vehicles, both aeronautics-and space-related,” according to data from the facility.

Broad studies there are “devoted to the fundamentals of hypersonic and high-temperature gas dynamics including detonation phenomena, supersonic combustion, chemical reactions, shock-wave/vortex interactions and thermal-chemical flow characteristics.” The lab helps lead several Chinese technology programs for scramjet propulsion. This includes basic hypersonic vehicle designs that could mate with a scramjet engine, as well as computational fluid dynamics work to assess the challenge of coupled ramjet/scramjet inlet flow fields at the front of the vehicle.

Scramjet ignition technology and work on cooling the internal walls of a scramjet are also being assessed, the Chinese say. Computer modeling of scramjet combustion instability is also being modeled.

“At the present time, the emphasis on rocket-based combined cycle [RBCC] scramjet research has gradually transferred from research and performance studies to some ground experiments and structures design,” says Wang Houqing, a researcher at Northwestern Polytechnical University in Xian. NPU is one of China’s top aerospace research centers.

“A copper model scramjet is ready for testing” in the new Gas Dynamics Laboratory facility, says Xinyu.

“The facility is to provide high enthalpy [thermal dynamic] model scramjet testing,” he says.

The facility uses a hydrogen/air and oxygen replenishment combustion heater with a flow rate of 3.5 kg./sec., with temperature capabilities up to 2,000K. It can generate test velocities up to Mach 5.6, according to Xinyu.

Many different scramjet combustor configurations have been tested so far, he says. But the new facility will allow complete scramjet engine model configurations to be evaluated instead of just the combustor alone.

Other Chinese scramjet research presented at Cincinnati included:

•Aerodynamic performance of Chinese waverider designs integrated with an inlet. “Simulation studies were conducted to investigate forebody-inlet-isolator performance in an airframe-scramjet integrated hypersonic vehicle,” according to Liu Zhenxia, also at NPU.

•Multicode computational fluid dynamics runs for coupled ramjet/scramjet inlet flowfields. This work models the transition from “ram” to “scram” propulsion. The research is underway at the Beijing University of Aeronautics and Astronautics.

•Research of gas discharge coefficients. This work is being conducted at the College of Aerospace and Materials Engineering at the National University of Defense Technology in Changsha.

•Cross-section design of a controllable hypersonic inlet. The research is being done at the Nanjing University of Aeronautics and Astronautics.

•Scramjet combustion mode translation studies. This work is also part of the scramjet effort at the National University of Defense Technology.

•Hydrogen injection and scramjet ignition testing. The research is being done in the Defense Technology university.

•Thermal and structures studies. NPU is performing heat transfer analysis and overall scramjet thermal structure design, including analysis of different materials used in the scramjet concepts.

•Numerical simulation of combustion instability. This work is also being pursued in Xian.China Developing Scramjet Propulsion

Sep 2, 2007
By Craig Covault


China is starting to ramp up its scramjet propulsion work—an initiative that will benefit high-speed missile programs while also helping the country to develop advanced aerospace materials, greater computational capabilities and a cadre of young engineers who have matured as a result of cutting-edge engine and aerodynamic challenges.

Building on its ramjet experience, China is embracing the much more difficult task of developing Mach 5 air vehicle concepts in which propulsion and aerodynamics are highly coupled.

As part of this effort, an integrated scramjet model is about to begin testing at up to Mach 5.6 in a new wind tunnel in Beijing.

In addition to the technology and engineering experience to be gained, the mid-term military payoff is likely to be more advanced high-speed tactical and medium-range Chinese missiles, especially for antiship warfare that could threaten U.S. aircraft carriers in the Pacific or operating in support of Taiwan.

“China has the greatest potential to compete militarily with the U.S. and field disruptive military technologies that could, over time, offset traditional U.S. military advantages,” the 2006 Pentagon Quadrennial Review said about overall Chinese military technology initiatives.

And over the next several decades, the scramjet work could eventually provide China with a tactical hypersonic global-strike capability beyond the country’s strategic ballistic missile force. The U.S. has similar goals for its own growing scramjet program.

The Chinese allowed a peek into multiple aspects of their scramjet efforts at the recent American Institute of Aeronautics and Astronautics Joint Propulsion Conference in Cincinnati. Chinese engineers from several research facilities presented about a dozen papers on their scramjet developments, as well as details on the new wind tunnel.

At the same forum, their papers revealed new rocket propulsion research, including work on hybrid systems that use a combination of propellants easier to handle and store than most propellants in wider use today. New insight also was offered on Chinese solid rocket motor technology work, important for both missile and space launch applications.

The Cincinnati meeting differed from a traditional U.S. industry gathering, because nearly a dozen engineers from Iran also submitted papers on Iranian solid and liquid rocket technologies. The Iranian engineers are based at the Sharif University of Technology and the KNT Technical University, both in Tehran. They apparently did not deliver the papers in person. However, as participants, the Iranians have access to all of the highly detailed U.S. aircraft and rocket propulsion presentations made at the conference.

A scramjet (supersonic combustion ramjet) flies at Mach 5 or faster using hydrogen fuel and oxygen out of the air for oxidizer. The engine must combine an advanced ramjet that changes configuration to swallow supersonic flow above about Mach 4.

Advanced ramjet technologies are also important for scramjet development, and the Chinese have been active in this area for decades.

Ironically, one the more interesting historical papers presented at the forum was a detailed description of how the U.S. Air Force and Lockheed combined top-secret ramjet propulsion technologies with segmented solid rocket boosters for the Mach 3 D-21B reconnaissance drones that were launched by modified SR-71s and B-52Hs in the late 1960s (see center photo). The D-21B was specifically developed to gather intelligence over China.

This was the first time details on the segmented rocket booster portion of the D-21B program have been presented publicly, says Robert Geisler of Geisler Industries, who led the analysis with retired Pratt & Whitney and ATK Tactical Propulsion engineers. Segmented boosters use individual circular sections like space shuttle solid rocket motors.

China already has such segmented solid rocket motor and ramjet capabilities today, but scramjets are a much greater challenge.

Although nowhere nearly as advanced as U.S. scramjet work, Chinese activities in this discipline will give the Defense Dept. additional impetus to argue for strong, ongoing U.S. hypersonic propulsion funding. Diverse U.S. technology programs are already underway to support development of the X-51 scramjet test vehicle (AW&ST July 23, p. 23).

As part of the Chinese effort, the engineers say new analytical centers are also being developed. For example, a Hypersonic Propulsion Test Facility has been built to support the scramjet program, according to Xinyu Chang, a senior researcher at the Laboratory of High-Temperature Gas Dynamics in Beijing, where the HPTF is located. Gas Dynamics lab research is specifically oriented to “the development of hypersonic flight vehicles, both aeronautics-and space-related,” according to data from the facility.

Broad studies there are “devoted to the fundamentals of hypersonic and high-temperature gas dynamics including detonation phenomena, supersonic combustion, chemical reactions, shock-wave/vortex interactions and thermal-chemical flow characteristics.” The lab helps lead several Chinese technology programs for scramjet propulsion. This includes basic hypersonic vehicle designs that could mate with a scramjet engine, as well as computational fluid dynamics work to assess the challenge of coupled ramjet/scramjet inlet flow fields at the front of the vehicle.

Scramjet ignition technology and work on cooling the internal walls of a scramjet are also being assessed, the Chinese say. Computer modeling of scramjet combustion instability is also being modeled.

“At the present time, the emphasis on rocket-based combined cycle [RBCC] scramjet research has gradually transferred from research and performance studies to some ground experiments and structures design,” says Wang Houqing, a researcher at Northwestern Polytechnical University in Xian. NPU is one of China’s top aerospace research centers.

“A copper model scramjet is ready for testing” in the new Gas Dynamics Laboratory facility, says Xinyu.

“The facility is to provide high enthalpy [thermal dynamic] model scramjet testing,” he says.

The facility uses a hydrogen/air and oxygen replenishment combustion heater with a flow rate of 3.5 kg./sec., with temperature capabilities up to 2,000K. It can generate test velocities up to Mach 5.6, according to Xinyu.

Many different scramjet combustor configurations have been tested so far, he says. But the new facility will allow complete scramjet engine model configurations to be evaluated instead of just the combustor alone.

Other Chinese scramjet research presented at Cincinnati included:

•Aerodynamic performance of Chinese waverider designs integrated with an inlet. “Simulation studies were conducted to investigate forebody-inlet-isolator performance in an airframe-scramjet integrated hypersonic vehicle,” according to Liu Zhenxia, also at NPU.

•Multicode computational fluid dynamics runs for coupled ramjet/scramjet inlet flowfields. This work models the transition from “ram” to “scram” propulsion. The research is underway at the Beijing University of Aeronautics and Astronautics.

•Research of gas discharge coefficients. This work is being conducted at the College of Aerospace and Materials Engineering at the National University of Defense Technology in Changsha.

•Cross-section design of a controllable hypersonic inlet. The research is being done at the Nanjing University of Aeronautics and Astronautics.

•Scramjet combustion mode translation studies. This work is also part of the scramjet effort at the National University of Defense Technology.

•Hydrogen injection and scramjet ignition testing. The research is being done in the Defense Technology university.

•Thermal and structures studies. NPU is performing heat transfer analysis and overall scramjet thermal structure design, including analysis of different materials used in the scramjet concepts.

•Numerical simulation of combustion instability. This work is also being pursued in Xian.