G1900-1-3 Effect of heat transfer in supersonic region of Laval nozzle on thrust and specific impulse

Hydrogen is adopted as coolant for regenerative cooling nozzle and reactor reflector in nuclear thermal propulsion (NTP), which may be a promising technology for human space exploration in the near future due to its large thrust and high specific impulse. During the cooling processes, the hydrogen experiences the transition from subcritical state to supercritical state, which influences the heat transfer severely. This paper is intended to study the characteristic of convective heat transfer to supercritical hydrogen in a straight tube under high heat flux through numerical simulation, which is a common phenomenon in NTP operation. The thermophysical properties and transport properties including the equation of state, specific heat capacity, viscosity and thermal conductivity of hydrogen are evaluated firstly by compared with the data from National Institute of Standards and Technology (NIST). Then, the flow and heat transfer process is investigated using Reynolds Averaged Naiver-Stokes (RANS) model, and the approach is validated by the successfully predicted behavior called local heat transfer deterioration. Moreover, the mechanism of heat transfer deterioration is analyzed briefly according to the detailed information of flow field. This work herein contributes to the further NTP design and research.

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Effects of Heat Transfer in Divergent Section of Laval Nozzle on Exhaust Velocity and Area Ratio

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ◽

10.2322/tjsass.54.212 ◽

2011 ◽

Vol 54 (185/186) ◽

pp. 212-220

Author(s):

Yuki IWAKI ◽

Tsuyoshi TOTANI ◽

Masashi WAKITA ◽

Harunori NAGATA

Keyword(s):

Heat Transfer ◽

Laval Nozzle ◽

Area Ratio

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4105 Study on Heat Transfer Characteristics in a Throat of Laval Nozzle by Using Shock Tunnel

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2007.5.0_355 ◽

2007 ◽

Vol 2007.5 (0) ◽

pp. 355-356

Author(s):

Yusuke ODA ◽

Kenichiro TAKEISHI ◽

Shigenori MITSUI

Keyword(s):

Heat Transfer ◽

Laval Nozzle ◽

Shock Tunnel ◽

Heat Transfer Characteristics ◽

Transfer Characteristics

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Investigation of Heat Transfer and Scale Effects on the Performance of a Giffard Injector-Pumped Microrocket

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4005074 ◽

2011 ◽

Vol 3 (4) ◽

Author(s):

Natalya A. Brikner ◽

William G. Gardner ◽

Jonathan M. Protz

Keyword(s):

Heat Transfer ◽

Scale Effects ◽

Specific Impulse ◽

Weight Ratio ◽

Engine Performance ◽

Chamber Pressure ◽

Rocket Engines ◽

Static Structure ◽

Novel Approach ◽

Large Scope

A novel approach to propellant pressurization for microscale rocket engines is introduced. The Giffard injector is shown to be a viable alternative to turbomachinery for pressurizing the liquid propellants on board a microrocket, offering a design free of moving parts. Extending the authors’ previous work, the engine performance is computed for several fuel/oxidizer combinations. A large-scope study of the heat transfer throughout the regenerative cooling engine cycle examines the effects of combustion chamber pressure and engine size on performance. A boiler is designed that facilitates the heat transfer required for adequate cooling and is modeled using the effectiveness-number of transfer units method. The computed specific impulse and thrust-to-weight ratio of the design for the propellants considered are roughly 250 s and 2000, respectively. The power density of the proposed injector-pumped design is seen to behave like that of turbopumped microrockets up to a critical nozzle throat diameter of approximately 1 cm, beyond which the advantages of an entirely static structure are outweighed by decreasing performance.

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Study of Supersonic Micro-Channel for Cooling Electronic Devices

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73134 ◽

2013 ◽

Cited By ~ 2

Author(s):

Yuya Takahashi ◽

Junnosuke Okajima ◽

Yuka Iga ◽

Atsuki Komiya ◽

Wu-Shung Fu ◽

...

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Gas Flow ◽

Single Phase ◽

Laval Nozzle ◽

Cooling System ◽

Supersonic Nozzle ◽

Cooling Performance ◽

Micro Scale ◽

Mean Temperature

In this study, we focus on a micro-scale cooling device using a supersonic single phase gas flow. The single phase gas cooling system has advantages for cooling electronics device in a micro-scale. Generally, the forced convective heat transfer by single phase gas flow has a lower heat transfer coefficient than other heat transfer mechanisms. However, the heat transfer rate can be largely improved with a low temperature flow that is generated by isentropic expansion in supersonic nozzle. The objective of this study is to conduct a numerical evaluation of the possibility of this cooling system with a supersonic air flow through a heated micro-fin array. In order to calculate the supersonic flow inside the nozzle and evaluate the effect of the nozzle shape on the heat transfer, two types of nozzles are designed. One nozzle is a typical supersonic nozzle called Laval nozzle. The other is named Bump nozzle which has a simple arc shape at the throat. The channel size of both nozzles are about 200 μm in width and 2743.1 μm in length. In order to estimate the cooling performance, the numerical simulations were conducted by using ANSYS FLUENT 12.1 with the density-based Roe-FDS method. The inlet pressure, outlet pressure, and total pressure were set to 290 kPa, 100 kPa, and 367.1 kPa, respectively. The stagnation temperature and wall temperature were assumed 300 K and 350 K, respectively. The values of bulk mean temperature and Nusselt number were estimated. In both nozzles, the calculated bulk mean temperature was about 230 K and the Nusselt number was 7.54, which is the theoretical value of laminar forced convection between the parallel plates. The results showed that the Bump nozzle had almost the same cooling performance as the Laval nozzle in spite of its simple geometry in the each single channel. In addition, the Bump nozzle can have 4 times the number of channels the Laval nozzle configuration can occupy the same area because of its shape. This indicates that cooling performance of a device that includes the Bump nozzle geometry is higher than that of the Laval nozzle.

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