Juan Fu

Analysis of Self-Pressurization Phenomenon in a Cryogenic Fluid Storage Tank With VOF Method

The self-pressurization phenomenon is studied numerically with the Volume of Fluid (VOF) method in a cryogenic fluid tank. Heat and mass transfer modelling is used for the phase change calculation at the interface. Transient simulations of the vaporization and pressure rise in a cylindrical liquid hydrogen tank are performed. The computations are carried out by using the CFD software package, Ansys Fluent, and an in-house developed code to calculate the source term associated with the phase change. Effects of the heat flux, fill level and gravity acceleration are investigated. Numerical results indicate that the pressure starts to rise after a certain time of sidewall heating and pressure rises gradually once the vaporization occurs. The rise rate increases as time elapses and is larger at higher heat flux at the same time. Multiple loops are observed in the fluid flow and thermal stratification is developed. The stratification degree is nearly the same for different fill levels at the same heat flux while the pressure rise rate increases as the fill fraction becomes larger. High temperature area appears when the fluid mixing becomes weaker as gravity acceleration decreases. Heat transfer turns to nucleate boiling at the wall from convection. as evaporation occurs at the interface. (Less)

Ultrasonic flow meter for propellant on-orbit gauging based on folded multi-tone phase measurement: Model analysis

Ultrasonic flow meter which provides non-invasive no-moving-parts construction is one of the fasted-growing technologies in flow gauging. Based on the general elasticity theory, this paper investigates sound wave propagation in elastic solid, as well as the mathematical description of ultrasonic transducer with the help of electric-acoustic analysis. Moreover, wave phenomenon in moving fluid is introduced and a general solution of wave propagation in cylindrical bounded pipeline is obtained based on the perturbation theory. Furthermore, a mathematical modeling of the ultrasonic flow meter is established in the uniform fluid velocity profile using continuous wave and a novel solution based on modified multi-tone phase measurement is investigated with the advantage of cancellation of impact of complex cylindrical waveguide in different modes which is widely available in pulse-wave-based measurement application. In the end, phase lock loop (PLL) is introduced and analyzed in the signal processing of noise attenuation and phase shift tracking.

Aerospace Heat Exchangers

This chapter introduces several typical applications of heat exchangers in aerospace systems and presents several concepts of heat exchangers, which have been used in aerospace or may be considered as promising designs for aerospace industry.

Computational Methods for the Investigations of Heat Transfer Phenomena in Aerospace Applications

This chapter introduces computational methods, in particular, computational fluid dynamics (CFD), and also gives a brief description of their development. The basic concepts are presented and then the focus is on the so-called finite volume method. At the end of the chapter, examples related to aerospace-specific topics are given. The important topic of shock wave–boundary layer interaction is also discussed.

Heat Pipes for Aerospace Application

This chapter gives a review of heat pipes for aerospace applications and also presents the basic principles of the operation of heat pipes. Various types of heat pipes are discussed. Limitations, design and manufacturing considerations, and developments are discussed.

Microgravity Heat Transfer

The importance of reduced gravity on heat transfer processes is highlighted. In particular, solidification, melting, single-phase convection, condensation, and evaporation are discussed. A detailed analysis of microgravity effects on cryogenic liquid hydrogen tanks is presented.

Low-Density Heat Transfer: Rarefied Gas Heat Transfer

The basics of low density in gas flows are described. How to deal with noncontinuum effects is presented. The various flow regimes are presented. A few numerical examples are used to illustrate simple calculation procedures and the importance of rarefaction. The relevance of heat transfer in microchannels is also considered.

Aerodynamic Heating: Heat Transfer at High Speeds

A physical description of aerodynamic heating is presented. The theory is presented for a flat plate boundary layer flow, and important parameters such as adiabatic wall temperature and recovery factor are introduced. A method to calculate the heat flux is outlined. A simple illustrative numerical example is described. An engineering practical system is analyzed.

The Measurement of Dynamic Pressure in Tank During the Compression Process

The measurement of dynamic pressure is quiet different from that of static pressure. It depends on the frequency resonance characters which are first discussed in this paper. It is obvious that the output of the measured dynamic pressure is no long proportional linearly to the input with the static sensitivity. The amplitude and the phase of the output both vary with the frequency of the pressure and the natural frequency of transducer. The analysis gives some guidance to us how to select proper sensor for practical need and how to improve the performance of the sensor under the given amplitude error. Besides, when the transducer is not flush with the tank wall but connected to the storage tank by a long narrow lead-in tube, a correcting model is presented which shows that the transducer measured pressure differs from the pressure in the tank. The transducer acts as a spring and the liquid in the tube as a mass. Further, this work is compared to the experiential computing equation and the difference is illustrated.

Notice of Retraction Simulation of heat transfer and mass transfer in cryogenic propellant tank slight volume compression

A cryogenic liquid quantity gauge for low-g application is described, named the Compression Mass Gauge (CMG), operates on the principle of slightly changing the volume of the tank by an oscillating bellows. The resulting pressure change is measured and related by thermodynamics to the volume of vapor in the tank, from which the volume of liquid is computed. The mathematical model of propellant tank with slight volume compression process is built. The mass transfer and heat transfer models among gaseous proportion and cryogenic propellant are projected in order to obtain the variation laws about the parameters, such as pressure and temperature in the gaseous proportion, propellant flux of volatilization, tank wall temperature and so on. Differential equation group is comprised of actual gas state equation, conversation of energy equation, mass and heat transfer equations. The differential equation group is calculated by the means of four steps Runge-Kutta Method. The effect of the compression volume and propellant flux of volatilization to the parameters in gaseous proportion is discussed.