Hot Gas Valve Research Articles

Modification of the Fiber-Matrix Interface in the Carbon Fiber Reinforced ZrB<sub>2</sub>- Based Ultra-High Temperature Ceramic Composites

Carbon fiber reinforced ultra-high temperature ceramic composite (Cf/UHTC) is a typical structural material currently used for aero-engine parts, hot gas valve parts, and thermal protection systems. However, for Cf/UHTC, one of the key issues is that the carbon fibers may be prone to react with the matrix of UHTC during the high-temperature sintering process. This paper mainly focused on restraining the serious fiber-matrix interfacial reaction. The carbon fiber reinforced ZrB2-based composite (Cf/ZrB2-based composite) was selected as the research material in the current work. Some processing methods were adopted to restrain the fiber-matrix interfacial reaction. Microstructure analysis, element distribution, and phase composition were characterized by using scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The results indicated that the matrix/fiber interfacial reaction in the Cf/ZrB2-based composite was closely related to the processing methods.

핀틀이 적용된 고온 가스 밸브의 비정상상태 해석 기법에 관한 연구

핀틀이 적용된 고온 가스 밸브의 비정상상태 해석 기법에 관한 연구

Normalized Pseudo-Control for Solid Divert & Attitude Control System

Faster trajectory correction and control mechanisms are required to correct the radar handing-over error coupled with homing guidance demands for Missile Interceptors. Solid Divert and Attitude Control System (SDACS), which typically have a very low time constant, is one of the most efficient and accurate way to meet these demands. The SDACS has challenges both with respect to the Hot Gas Valve (HGV) technology as well as actuator requirements. The paper proposes a novel method to simplify the controller design and reduce actuator needs for the rotary hot gas valves based SDACS. The proposed method formalizes a linear Pseudo-control to track the lateral acceleration and attitude correction commands. The pseudo-control requirements are tracked through the HGV rotations. The paper further proposes the normalization of the pseudo-control to make the controller generic making it invariant of the valve size and relative dimensions of the HGV’s static & moving part. The paper also proposes a technique to reduce the number of actuators required for the full SDACS system by use of these near affine pseudo-controls.

A study on the unsteady conjugate heat transfer of hot gas valve

Numerical simulations of a hot gas valve were conducted in this study to establish an analysis method. The far-field effect was also checked to select a computational domain. The existence of the far-field did not affect flow and temperature characteristics. The grid sensitivity was checked by varying the grid number from 25,000 to 120,000. The thrusts were similar according to the number of grid. However, differences in temperature distribution were observed.Three turbulence models were adopted to determine the influence of turbulence on thrust and temperature distribution: Spalart–Allmaras, RNG k–ε, and k–ω SST. The thrusts of the hot gas valve were similar in all simulation cases. However, an approximately 2% deviation in temperature distribution was observed at an operating pressure of 128 atm.Time step size and iteration were selected for the unsteady analysis. The analysis was conducted using only an S–A turbulent model and a valve grid. No significant difference was found. Hence, the time step size was set as 10 μs, and 50 iterations were performed. The unsteady analysis was conducted by increasing the time step size throughout the four sections considering the operating time of the hot gas valve. The time step size was increased when the quantitative result reached within 5% difference in each section. The flow, pressure, and temperature fields in the flow area reached the steady state with within 5% difference at 8 ms, 100 ms, and 5.5 s, respectively. The three fields in the flow area reached the steady state at 10 s from the operating time of the hot gas valve. However, an approximately 7% difference in temperature field was observed in the solid area. The calculation time was reduced by approximately 130 times compared to the existing calculation method.

핀틀이 적용된 고온 가스 밸브 유동장 해석 기법에 관한 연구

고온밸브의 열/유동 해석을 수행함에 있어 난류모델의 선정 및 해석영역의 변화가 해석 결과에 미치는 영향을 확인하기 위한 연구를 수행하였다. 격자 민감도를 확인하기 위해 100,000~1,700,000 개의 격자에 대해 계산을 수행 하였다. 각각의 난류모델 Spallart-Allmaras, RNG <TEX>$k-{\varepsilon}$</TEX>, <TEX>$k-{\omega}$</TEX> SST에서 추력 값은 동일하였지만 온도 분포에서 5% 이내의 차이가 존재 하는 것을 확인 할 수 있었다. 계산 영역을 설정함에 있어 외부 대기 영역은 유동과 온도에 큰 영향을 미치지 않았다. 격자수 변화에 따라 추력 값은 동일하였다. 외부 대기 영역이 존재할 때 격자수 변화에 따라 추력 값은 동일하였지만 온도 분포에서는 차이가 존재 하였다. Numerical simulations of the hot gas valve with a pintle have been conducted in order to investigate the effect of numerical methods and computational domains. The grid sensitivity is checked by varying the grid number from 100,000 to 1,700,000. The existence of ambient region doesn't make the significant differences of the flow-field and the temperature distribution. Three turbulence models are adopted to figure out its influence on the thrust and temperature distribution: Spallart-Allmaras, RNG <TEX>$k-{\varepsilon}$</TEX>, <TEX>$k-{\omega}$</TEX> SST. The thrusts of the hot gas valve are almost same in all cases of the simulation, however, there are about 5% difference in the temperature distribution. With the ambient region, the difference are observed in the temperature distribution with respect to the number of grids.

An example of successful international cooperation in rocket motor technology

The history of over 25 years of cooperation between Pratt & Whitney, San Jose, CA, USA and Snecma Moteurs, Le Haillan, France in solid rocket motor and, in one case, liquid rocket engine technology is presented. Cooperative efforts resulted in achievements that likely would not have been realized individually. The combination of resources and technologies resulted in synergistic benefits and advancement of the state of the art in rocket motors and components. Discussions begun between the two companies in the early 1970's led to the first cooperative project, demonstration of an advanced apogee motor nozzle, during the mid 1970's. Shortly thereafter advanced carboncarbon (CC) throat materials from Snecma were comparatively tested with other materials in a P&W program funded by the USAF. Use of Snecma throat materials in CSD Tomahawk boosters followed. Advanced space motors were jointly demonstrated in company-funded joint programs in the late 1970's and early 1980's: an advanced space motor with an extendible exit cone and an all-composite advanced space motor that included a composite chamber polar adapter. Eight integral-throat entrances (ITEs) of 4D and 6D construction were tested by P&W for Snecma in 1982. Other joint programs in the 1980's included test firing of a “membrane” CC exit cone, and integral throat and exit cone (ITEC) nozzle incorporating NOVOLTEX® SEPCARB® material. A variation of this same material was demonstrated as a chamber aft polar boss in motor firings that included demonstration of composite material hot gas valve thrust vector control (TVC). In the 1990's a supersonic splitline flexseal nozzle was successfully demonstrated by the two companies as part of a US Integrated High Payoff Rocket Propulsion Technology (IHPRPT) program effort. Also in the mid-1990s the NOVOLTEX® SEPCARB® material, so successful in solid rocket motor application, was successfully applied to a liquid engine nozzle extension. The first cooperative effort for the new millennium, a scale-up of the supersonic splitline flexseal nozzle, was begun in 2001. Key details of the above numerous cooperative successes are presented.

Experience gained from the eva II and KVK operation

This paper deals with tasks, structure and experience gained from the two helium test facilities, EVA II and KVK, which are part of the main tools within the framework of component development for a high-temperature reactor. Special techniques (internal insulation, cooling by using cold gas) for the components became necessary to separate high temperatures (950°C) from the pressure-loaded component parts. The question of helium atmosphere and its interaction with high-temperature materials could be sufficiently investigated. Well-developed oxide layers were obtained on the helium side. Excellent reliability and flexibility of the facilities have been obtained. The following components have been tested in due time and at moderate costs: • • Steam reformers • • Helium heat exchangers • • Steam generators • • Hot gas valves • • Hot gas ducts • • Blowers In addition to the experimental results practical experience gained with helium technology is of essential importance for further work relating to HTR development and design.

高温ヘリウムガスライン用圧力制御弁の開発試験

高温ヘリウムガスライン用圧力制御弁の開発試験

Direct Mixing and Combustion Efficiency Measurements in Ducted, Particle-Laden Jets

Using water-cooled probes and hot-gas valves, gas-particle samples were withdrawn from the secondary duct of an air-augmented laboratory burner. Using a boron-loaded propdlant, air/fuel ratio and secondary duct pressure were varied from 12/1 to 32/1 and from 82 to 127 psia, respectively. From sample analysis of chlorine, argon (air tracer), boron, and boron oxide, radial and axial profiles of air, gaseous fuel, participate fuel and percent of boron combustion were determined. Particles and gases mixed at significantly different rates. Measured gasphase mixing rates were comparable to model predictions, which assumed particles to be in equilibrium with gases. Boron combustion efficiency varied markedly with duct position, air/fuel ratio and secondary chamber pressure. Low boron combustion efficiency resulted principally from delayed ignition of the gaseous fuels after dilution by air reduced resulting gas-phase temperatures below the boron ignition temperature. This was especially true at low secondary duct pressures.

Technical Literature Digest (MAY 1963)

Development of a Solid Rocket Propellant System Capable of Withstanding Extended Storage in a Space Environment. Thiokol Chemical Corp., Elkton Div. Quart. Progr. Rept. 2, Rept. E19462, Dec. 12, 1962, 55 pp. Development of a Hot Gas Valve, W. C. Stone. Rohm & Haas Co., Redstone Arsenal Res. Div. Rept. S-37, Nov. 30, 1962, 14 pp. The Testing and Development of a Ground Muffler for Jet Engine Exhaust Noise, D. Middleton. Gt. Brit. Aeronaut. Res. Council, Current Paper 610, Dec. 1961 (1962), 26 pp. (ARC 23,507). Some Three-Dimensional Effects of Rotating Stall, S. L. Dixon. Gt. Brit. Aeronaut. Res. Council, Current Paper 609, May 1961 (1962), 35 pp. (ARC 22,863). NASA-Industry Conference on the Science and Technology of Space Exploration, Chicago, Nov. 1-3, 1962, NASA SP-11. Vol. 2, 532pp. New Problems Encountered with Pumps and Turbines, M. J. Hartmann and C. L. Ball, pp. 23-36, 22 refs. Current Research and Development on Thrust Chambers, E. R. Jonash and W. A. Tomazic, pp. 43-52, 23 refs. Dynamics and Control of Chemical Rockets, J. C. Sanders and L. M. Wenzel, pp. 53-56. Advances in Astronautical Propulsion (Seminar on Astronomical Propulsion, Milan, 1960), Proceedings, edited by C. Casci (Pergamon Press, New York, 1962), 366 pp. Design and Application of Large SolidPropellant Propulsion Systems, J. Buchanan, pp. 47-62. Physico-Chemical Problems Related to Solid Propellant Propulsion (Abstract), M. Summerfield, pp. 63-70, 27 refs. Design, Development and Operation of Liquid Rocket Vehicles, A. 0. Tischler, pp. 71-106, 220 refs. Horizons in Liquid-Propellant Rocket Propulsion, S. S. Penner and L. L. Bixson, pp. 107-146, 42 refs.