Detonation-driven Shock Tunnel Research Articles

China’s Detonation-driven Shock Tube Wind Tunnels: A Case Study of Transnational Science in Aeronautics during the Cold War

From the perspective of the history of technology, this paper reviews the development of a hypersonic wind tunnel in China. The key figure is Yu Hongru 俞鸿儒, who began his research into shock tube wind tunnels in the 1950s, and proposed ways to use detonation driver technology. His insight, however, was stymied during China's “Cultural Revolution.” After China’s reform and opening-up began in the late 1970s, Yu 俞 designed a hypersonic tunnel driven by backward hydrogen-oxygen detonation utilizing a dumping section and carried out verification experiments with RWTH Aachen University. After 2000, the high-temperature gas dynamics team of the Institute of Mechanics of the Chinese Academy of Sciences built the first long test-duration detonation-driven shock tunnel. This case study draws extensively upon Chinese literature, documents, and interviews. It adds to the history exploring Cold War science and technology. While much research has focused on activities in the USA and the USSR, this article contributes to the less-explored history of scientific research and development in China after 1950, demonstrating the importance of knowledge flows within the wider concept of Cold War transnational science. In addition, this transnational emphasis contributes a non-western chapter to the western-centric history of aerospace technology development.

Numerical modeling of a high-enthalpy shock tunnel driven by gaseous detonation

A detonation-driven shock tunnel is useful as a ground test facility for hypersonic flow research. Numerical modeling of the shock tunnel is an easy way to extract precise test flow conditions and generate predictions of new operating conditions. In this study, a quasi-one-dimensional modeling of a detonation-driven shock tunnel is described. The model accounts for the viscous effects within a shock tube by adding a source term. The simulations of the particular conditions of the detonation shock tunnel are then presented and compared with the experimental results. The simulations provide good estimates for both the shock speed and pressure distributions. Detailed information on the gas dynamic processes over the full length of the facility is also obtained and discussed. The results also show that the approach is valid and ideal for the development of new tunnel operating conditions. It is also an ancillary tool for characterization of the reservoir parameters in a shock tube/tunnel, especially for the total temperature which are difficult to measure in such facilities.

Investigation of dual ignition for a detonation-driven shock tunnel in forward driving mode

A detonation-driven shock tunnel is useful as a ground test facility for hypersonic flow research. The forward detonation driving mode is usually used to achieve high-enthalpy flows due to its strong driving capability. Unfortunately, the strong detonation wave front results in diaphragm fragments that disturb the test flow and scratch the nozzle or test models. In this study, a dual ignition system was developed to burst a metal diaphragm without fragmentation in the forward driving mode. A series of experiments were conducted to validate the proposed technique. The influences of the delay time setting on the test conditions were investigated in detail. Numerical simulations were also conducted to obtain a better understanding of the wave processes in the shock tube. The results showed that the dual ignition system solved the diaphragm issues in the forward driving mode. The test time was shortened due to the additional ignition close to the primary diaphragm; the smaller the delay time, the shorter the effective test time. However, a small amount of time loss is considered worthwhile because the severe diaphragm problems have been solved.

Aerodynamic force and moment measurement of 10° half-angle cone in JF12 shock tunnel

An aerodynamic force and moment measurement was conducted in JF12 long-test-duration detonation-driven shock tunnel of Institute of Mechanics, Chinese Academy of Sciences. The test duration of JF12 is 100–130ms. The nominal Mach number is 7.0 and the exit diameter of the contoured nozzle is 2.5m. The total enthalpy is 2.5MJ/kg which duplicates the hypersonic flight conditions of Mach number 7.0 at 35km altitude. The test model is the standard aerodynamic force model of 10° half-angle sharp cone. The length of the test model is 1500mm and the weight is 57kg. The aerodynamic forces were measured with a six-component strain balance. The angles of attack were set to be −5°, 0°, 5°, 10° and 14°, respectively. The experimental results show that in the 100–130ms test duration, the signals of strain balance have 3–4 complete vibration cycles. So, the aerodynamic forces and moments can be obtained directly by averaging the signals of balance without acceleration compensation. The force measurement error of repeatability of JF12 is less than 2%. The aerodynamic force coefficients of JF12 are in good agreement with those of conventional hypersonic wind tunnels. For this test model at Mach number 7.0 and total enthalpy of 2.5MJ/kg, the real-gas effects on aerodynamic force characteristics are not very evident.

A big increase in shock tunnel test times

Why is it such difficult to develop hypersonic airbreathing propulsion? It is in need of a reliable ground test facility for ex-ploring the source of development obstruction. A big increase in shock tunnel test times for breaking the upper bound of Mach number 5 associated with airbreathing propulsion was proposed. Smaller diameter of detonation driver was adopted for decreasing Tailored incident shock Mach number, enabling the test times of detonation driven shock tunnel to be extended by a big margin. Test times of constructed detonation driven shock tunnel JF-12 were over 100 ms.

超長試験時間デトネーション駆動衝撃波風洞@中国科学院力学研究所(北京・中国)( グローバルAERO 海外空力機関訪問・滞在レポート 第5回)

超長試験時間デトネーション駆動衝撃波風洞@中国科学院力学研究所(北京・中国)( グローバルAERO 海外空力機関訪問・滞在レポート 第5回)

Performance Tests of JF-10 High-Enthalpy Shock Tunnel with a FDC Driver

JF-10 detonation-driven high-enthalpy shock tunnel was re-built with a forward detonation cavity (FDC) driver and the experimental data from its performance tests are summarized and reported in this paper. Test-duration of high-enthalpy flows produced with the improved JF10 is found to be extended by two times under the condition that the FDC driver is about 40% shorter than the original one. The uniform pressure area of the thus-obtained hypersonic flows in a 500 mm diameter conical nozzle is about 700 mm in length and 400 mm in diameter. Incident shock wave decay in the driven section appears to be much less by comparing with the original JF-10 shock tunnel. The performance improvement of JF-10 high-enthalpy shock tunnel was demonstrated to be very successful and high quality hypervelocity flows can be generated for aero-thermochemistry experiments.

Development and application of flexible substrate sensors in instantaneous heat flux measurement

A new type of sensor with the flexible substrate is introduced. It is applicable in measuring instantaneous heat flux on the model surface in a hypersonic shock tunnel. The working principle, structure and manufacture process of the sensor are presented. The substrate thickness and the dynamic response parameter of the sensor are calculated. Because this sensor was successfully used in measuring the instantaneous heat flux on the surface of a flat plate in a detonation-driven shock tunnel, it may be effective in measuring instantaneous heat flux on the model surface.

Experimental study on the flow field behind a backward-facing step using a detonation-driven shock tunnel

The supersonic combustion RAM jet (SCRAM jet) engine is expected to be used in next-generation space planes and hypersonic airliners. To develop the engine, stabilized combustion in a supersonic flow field must be attained even though the residence time of flow is extremely short. A mixing process for breathed air and fuel injected into the supersonic flow field is therefore one of the most important design problems. Because the flow inside the SCRAM jet engine has high enthalpy, an experimental facility is required to produce the high-enthalpy flow field. In this study, a detonation-driven shock tunnel was built to produce a high-enthalpy flow, and a model SCRAM jet engine equipped with a backward-facing step was installed in the test section of the facility to visualize flow fields using a color schlieren technique and high-speed video camera. The fuel was injected perpendicularly to a Mach 3 flow behind the backward-facing step. The height of the step, the injection distance and injection pressure were varied to investigate the effects of the step on air/fuel mixing characteristics. The results show that the recirculation region increases as the fuel injection pressure increases. For injection behind the backward-facing step, mixing efficiency is much higher than with a flat plate. Also, the injection position has a significant influence on the size of the recirculation region generated behind the backward-facing step. The schlieren photograph and pressure histories measured on the bottom wall of the SCRAM jet engine model show that the fuel was ignited behind the step.

Combustion Processes in Model SCRAM Jet Combustor Using Detonation Driven Shock Tunnel

Experiments were conducted in order to investigate mixing and combustion processes in a model SCRAM (Supersonic Combustion RAM) jet combustor equipped with a backward-facing step. A detonation-driven shock tunnel was used to generate high-enthalpy flow of Mach number three. Firstly, an influence of installing a sidewall on the combustor model was investigated. Secondly, flow-fields around the step were visualized using high-speed video camera with an aid of schlieren technique. A hydrogen fuel was injected perpendicular to the supersonic flow behind the backward-facing step and a height of the step and an injection distance were varied in order to investigate the effects of these parameters on a characteristic of the combustion. As a result, the injected hydrogen was ignited behind the step and increasing the height of step became effective to the ignition and flame holding behaviors. Furthermore, a non-dimensional injection distance with respect to height of the step was considered to be an important parameter to influence an ignition and combustion processes in the model SCRAM jet combustor.

Performance of a detonation driven shock tunnel

A detonation driven shock tunnel is useful as a ground test facility for hypersonic flow research. By attaching a convergent section ahead of the primary diaphragm in the driver section, the downstream operation mode became available to generate a high-enthalpy test flow. A 100 mm diameter shock tunnel was for the first time installed in the Laboratory of High-Temperature-Gas Dynamics (LHD), Institute of Mechanics, Chinese Academy of Sciences, and after its continuous refitments, a high performance detonation driven shock tunnel was achieved to generate high-enthalpy and high-Reynolds number test flows. A new method to burst a metal diaphragm with the downstream operation mode is discussed.

デトネーション駆動型衝撃風洞を用いた後ろ向きステップ周りの流れ場に関する実験的研究

As a research to develop a SCRAM-jet engine is actively conducted, a necessity to produce a high-enthalpy flow in a laboratory is increasing. In order to develop the SCRAM-jet engine, stabilized combustion in a supersonic flow-field should be attained, in which a duration time of flow is extremely short. Therefore, a mixing process of breathed air and fuel, which is injected into supersonic flow-fields is one of the most important problem. Since, the flow inside SCRAM-jet engine has high-enthalpy, an experimental facility is required to produce such high-enthalpy flow-field. In this study, a detonation-driven shock tunnel was built and was used to produce high-enthalpy flow. At first, a performance of this facility was investigated in order to obtain a Tayloring condition. Furthermore, SCRAM-jet combustor model equipped backward-facing step was installed at test section and flow-fields were visualized using color-schlieren technique. The fuel was injected perpendicular to the flow of Mach number three behind step. The height of backward-facing step and injection pressure were changed to investigate effects of the step on a mixing characteristic between air and fuel. The schlieren photograph and pressure histories show that the fuel was ignited behind step and the height of step is important factor to ignite a fuel in a supersonic flow-field.

Forward-Running Detonation Drivers for High-Enthalpy Shock Tunnels

To improve the quality of driving flows generated with detonation-driven shock tunnels operated in the forward-running mode, various detonation drivers with specially designed sections were examined. Four configurations of the specially designed section, three with different converging angles and one with a cavity ring, were simulated by solving the Euler equations implemented with a pseudo kinetic reaction model. From the first three cases, it is observed that the reflection of detonation fronts at the converging wall results in an upstream-traveling shock wave that can increase the flow pressure that has decreased due to expansion waves, which leads to improvement of the driving flow. The configuration with a cavity ring is found to be more promising because the upstream-traveling shock wave appears stronger and the detonation front is less overdriven. Although pressure fluctuations due to shock wave focusing and shock wave reflection are observable in these detonation-drivers, they attenuate very rapidly to an acceptable level as the detonation wave propagates downstream. Based on the numerical observations, a new detonation-driven shock tunnel with a cavity ring is designed and installed for experimental investigation. Experimental results confirm the conclusion drawn from numerical simulations. The generated driving flow in this shock tunnel could maintain uniformity for as long as 4 ms. Feasibility of the proposed detonation driver for high-enthalpy shock tunnels is well demonstrated.