Simulation of Propellant Loading System Senior Design Implement in Computer Algorithm

Propellant loading from the Storage Tank to the External Tank is one of the very important and time consuming pre-launch ground operations for the launch vehicle. The propellant loading system is a complex integrated system involving many physical components such as the storage tank filled with cryogenic fluid at a very low temperature, the long pipe line connecting the storage tank with the external tank, the external tank along with the flare stack, and vent systems for releasing the excess fuel. Some of the very important parameters useful for design purpose are the prediction of pre-chill time, loading time, amount of fuel lost, the maximum pressure rise etc. The physics involved for mathematical modeling is quite complex due to the fact the process is unsteady, there is phase change as some of the fuel changes from liquid to gas state, then conjugate heat transfer in the pipe walls as well as between solid-to-fluid region. The simulation is very tedious and time consuming too. So overall, this is a complex system and the objective of the work is student's involvement and work in the parametric study and optimization of numerical modeling towards the design of such system. The students have to first become familiar and understand the physical process, the related mathematics and the numerical algorithm. The work involves exploring (i) improved algorithm to make the transient simulation computationally effective (reduced CPU time) and (ii) Parametric study to evaluate design parameters by changing the operational condition

Modeling of Compressible Flow with Friction and Heat Transfer Using the Generalized Fluid System Simulation Program (GFSSP)

The present paper describes the verification and validation of a quasi one-dimensional pressure based finite volume algorithm, implemented in Generalized Fluid System Simulation Program (GFSSP), for predicting compressible flow with friction, heat transfer and area change. The numerical predictions were compared with two classical solutions of compressible flow, i.e. Fanno and Rayleigh flow. Fanno flow provides an analytical solution of compressible flow in a long slender pipe where incoming subsonic flow can be choked due to friction. On the other hand, Raleigh flow provides analytical solution of frictionless compressible flow with heat transfer where incoming subsonic flow can be choked at the outlet boundary with heat addition to the control volume. Nonuniform grid distribution improves the accuracy of numerical prediction. A benchmark numerical solution of compressible flow in a converging-diverging nozzle with friction and heat transfer has been developed to verify GFSSP's numerical predictions. The numerical predictions compare favorably in all cases

Fluid Transient Analysis During Priming of Evacuated Line

Pressure surges are critical in the design of spacecraft propellant feed lines. The pressure transients that occur during priming of feed lines are very important in the design and analysis of liquid propulsion systems. During the start-up of the propulsion system of a spacecraft, the process of filling of an evacuated pipeline is called priming. Priming can generate severe pressure peaks due to the slam (water hammer) of the propellant against a closed thruster valve. The downstream conditions strongly affect the pressure surge. In space systems, satellites, or interplanetary probes, the propellant lines are vacuum-pumped or filled with low pressure helium or nitrogen before the launch. Before operations, these lines are primed with a vaporizing liquid, sometimes in the presence of a non-condensable gas (NCG), which produces water hammer phenomena. The objective of the current study is to use a finite volume based network flow solver (Generalized Fluid System Simulation Program, GFSSP) for the numerical simulation of Priming in (a) a straight feedline and (b) a flow network. The geometrical configurations and dimensions for the pipe and other components used for the current study are identical to experimental study of Prickett et al

Network Flow Simulation of Fluid Transients in Rocket Propulsion Systems

Fluid transients, also known as water hammer, can have a significant impact on the design and operation of both spacecraft and launch vehicle propulsion systems. These transients often occur at system activation and shutdown. The pressure rise due to sudden opening and closing of valves of propulsion feed lines can cause serious damage during activation and shutdown of propulsion systems. During activation (valve opening) and shutdown (valve closing), pressure surges must be predicted accurately to ensure structural integrity of the propulsion system fluid network. In the current work, a network flow simulation software (Generalized Fluid System Simulation Program) based on Finite Volume Method has been used to predict the pressure surges in the feed line due to both valve closing and valve opening using two separate geometrical configurations. The valve opening pressure surge results are compared with experimental data available in the literature and the numerical results compared very well within reasonable accuracy (< 5%) for a wide range of inlet-to-initial pressure ratios. A Fast Fourier Transform is preformed on the pressure oscillations to predict the various modal frequencies of the pressure wave. The shutdown problem, i.e. valve closing problem, the simulation results are compared with the results of Method of Characteristics. Most rocket engines experience a longitudinal acceleration, known as "pogo" during the later stage of engine burn. In the shutdown example problem, an accumulator has been used in the feed system to demonstrate the "pogo" mitigation effects in the feed system of propellant. The simulation results using GFSSP compared very well with the results of Method of Characteristics

Modeling and Simulation for PVDF-based Pyroelectric Energy Harvester

Energy harvesting technology allows the capturing of unused ambient energy such as solar, wind, thermal, strain and kinetic, energy of gas and liquid flows which is then converted into another form of usable energy. This paper focuses on the thermal-electrical energy harvesting based on pyroelectric effect. Pyroelectric materials generate a voltage, when subjected temperature variation. The pyroelectric polyvinylidene fluoride (PVDF) films were fabricated and characterized for pyroelectric and dielectric parameters. Using the foregoing parameters, the energy-harvesting capacity has been theoretically explored by capturing thermal energy available in the environment of Huntsville (pavement), Saudi Arabia (ambient) and MARS (ambient). The predicted maximum cumulative voltage by the end of a 300 hours cycle is approximately 0.13, 0.7 and 7.7 volts for Huntsville and Saudi Arabia and MARS, respectively for the PVDF based 10 cm2 pyro-elements. The results indicate that the electrical energy harvesting via pyroelectricity holds promise for powering autonomous low-duty electric devices. Furthermore, the mathematical modeling and numerical simulations can be helpful in designing of pyroelectric micro-power generators

Piezoelectric power harvesting devices: An overview

This article reviews the fundamental behavior of piezoelectric for applications in sensors and energy harvesting technologies. In fact, many devices and applications are evolving day-to-day depending on smart materials technology such as, scanning probe microscope (SPM) and cigarette lighters. Today, vibration based energy harvesting via piezoelectric materials has become one of the most prominent ways to provide a limited energy for self-powered wireless sensor and low power electronics. This review provides an insight that involves mathematical modeling of constitutive equations, lumped parameter model, mechanisms of piezoelectric energy conversion, and operating principle of a piezoelectric energy harvesting system. This article also focuses on the dielectric, piezoelectric, mechanical, and pyroelectric properties of piezoelectric and pyroelectric materials open to use from single crystal such as PMN-PT through ceramics PZT and polymers such as PVDF. Recent important literature is also reviewed along with energy harvesting devices proposed for use in industrial and biomedical applications

Multi-Node Modeling of Cryogenic Tank Pressurization System using Generalized Fluid System Simulation Program

This paper presents a multi-node model of autogenous pressurization of cryogenic propellant in a flight tank using the Generalized Fluid System Simulation Program (GFSSP), a general purpose flow network code developed at NASA/Marshall Space Flight Center. Tests were conducted to measure the pressure and temperatures at the various axial locations of the stratified ullage at 75% and 45% fill level. Liquid nitrogen was pressurized by gaseous nitrogen from a supply tank while the drain valve from the tank remained closed during the pressurization process. The ullage was discretized into 25 uniformly distributed nodes: 5 in the radial direction and 5 in the axial direction assuming the flow to be axisymmetric. Heat and mass transfer between the liquid and vapor has been modeled at the liquid vapor interface. Heat transfer between wall and vapor at the ullage has been accounted for by assuming heat transfer occurs by natural convection. The model also accounts for heat leak to the tank through the insulation and metal wall by heat conduction. The predicted pressures and temperatures are compared with the measured data

2009 ESMD Space Grant Faculty Project Final Report

The Constellation Program is the medium by which we will maintain a presence in low Earth orbit, return to the moon for further exploration and develop procedures for Mars exploration. The foundation for its presence and success is built by the many individuals that have given of their time, talent and even lives to help propel the mission and objectives of NASA. The Exploration Systems Mission Directorate (ESMD) Faculty Fellows Program is a direct contributor to the success of directorate and Constellation Program objectives. It is through programs such as the ESMD Space Grant program that students are inspired and challenged to achieve the technological heights that will propel us to meet the goals and objectives of ESMD and the Constellation Program. It is through ESMD Space Grant programs that future NASA scientists, engineers, and mathematicians begin to dream of taking America to newer heights of space exploration. The ESMD Space Grant program is to be commended for taking the initiative to develop and implement programs that help solidify the mission of NASA. With the concerted efforts of the Kennedy Space Center educational staff, the 2009 ESMD Space Grant Summer Faculty Fellows Program allowed faculty to become more involved with NASA personnel relating to exploration topics for the senior design projects. The 2009 Project was specifically directed towards NASA's Strategic Educational Outcome 1. In-situ placement of Faculty Fellows at the NASA field Centers was essential; this allowed personal interactions with NASA scientists and engineers. In particular, this was critical to better understanding the NASA problems and begin developing a senior design effort to solve the problems. The Faculty Fellows are pleased that the ESMD Space Grant program is taking interest in developing the Senior Design courses at the university level. These courses are needed to help develop the NASA engineers and scientists of the very near future. It has been a pleasure to be part of the evaluation process to help ensure that these courses are developed in such a way that the students' educational objectives are maximized. Ultimately, with NASA-related content used as projects in the course, students will be exposed to space exploration concepts and issues while still in college. This will help to produce NASA engineers and scientists that are knowledgeable of space exploration. By the concerted efforts of these five senior design projects, NASA's ESMD Space Grant Project is making great strides at helping to develop talented engineers and scientists that will continue our exploration into space

Multi-Node Modeling of Cryogenic Tank Pressurization System Using Generalized Fluid System Simulation Program

Cryogenic Tanks are pressurized by inert gas such as Helium or Nitrogen to maintain the required pressure of the propellant delivered to the turbo-pump of a liquid rocket engine. Thermo-fluid system simulation tools are used to analyze the pressurization process of a cryogenic tank. Most system level codes (GFSSP and ROCETS) use single node1 to represent ullage which is the gaseous space in the tank. Ullage space in a cryogenic tank is highly stratified because the entering inert gas is at ambient temperature whereas the liquid propellant is at a cryogenic temperature. A single node model does not account for the effect of temperature gradient in the ullage. High fidelity Navier-Stokes based CFD model of Tank Pressurization is not practical for running a long duration transient model with thousands and millions of nodes. A possible recourse is to construct a multi-node model with system level code that can account for ullage stratification

Anti-tumor effect of fruit rind of Myristica malabarica in an Ehrlich ascites carcinoma model

Background: Among the various modalities of anti-cancer treatment, cancer chemotherapy plays a very vital role. The alarming side effects being its main drawback leads to relentless research for newer agents. A new natural agent with promising anti-cancer properties from in-vitro studies leads to this study. Here we have evaluated the anti-tumor activity of a crude extract of fruit rind of Myristica malabarica in an Ehrlich ascites carcinoma model in mice.Methods: A murine model of cancer was established with i.p. inoculation of Ehrlich Ascites carcinoma (EAC) cells; animals were divided into five groups (including normal control) to observe the inhibitory effect of a crude extract of the fruit rind of Myristica malabarica/rampatri (0-100mg/kg b.w. i.p.) as compared with methotrexate (0.4mg/kg bw., i.p.). Blood and ascitic fluid were collected on the 10th day for analysis.Results: In the EAC model, there was an increase in tumor volume, tumor weight, and tumor packed cell volume, which was decreased by rampatri (50 and 100mg/kg bw) along with an increase in the mean survival time (MST). Rampatri caused minimal alterations in hematological parameters, renal functions remained unchanged but an increase in hepatic SGOT was demonstrated.Conclusions: The crude extract of rampatri (containing Malabaricones) exhibited significant anti-tumor activity with minimal effect on hematological and renal functions