Design of a cold gas micro thruster

Keywords: Micro satellites, Micro propulsion, MEMS technologie

Modular Micro Propulsion System

The miniaturization of space applicable devices by means of MEMS technology is pursued by many research groups. MEMS devices are often designed as stand alone and require individual packaging which often makes them still quite large. Focusing on the integration of several MEMS components has the advantage of reducing size and mass much more. An integrated and miniaturized cold gas propulsion system for micro satellites is presented which consists of a valve, a particle filter, a pressure sensor, a nozzle and a gas tank. By selecting a convenient package first and adjusting the MEMS part to fit the package, costs are reduced and modularity is obtained. The baseline of the system is a glass tube bonded on a silicon disc which contains a valve seat as shown in Figure 1. The valve is normally closed by an embossed membrane which is stacked inside the glass tube. A piezo-disc is glued to the boss of the membrane to actuate the valve. The glass tube is functioning as hermetically sealed package as well as fluidic interconnect with the macro world. The pressure sensor and particle filter are suspended in the glass tube. This integrated system is connected to a pressurized N2 gas tank which is developed by TNO [1]. The tank contains 8 cold gas generators which makes it possible to reduce the working pressure to 3.4bar withoutcompromising on the amount of gas. During the symposium the technical development and results will be presented

An example of active learning in Aerospace Engineering

This paper is a showcase for an on-going active learning capstone design project in the BSe. programme at the Faculty of Aerospace Engineering at Delft University of Technology. In multi-disciplinary teams supervised by tutors from different backgrounds students work towards an Aerospace (related) design. In the exercise students learn about applying knowledge, working in teams, sustainable development, project management, reporting, presenting and design in a semi-professional environment

Spaceplane flight simulation: Project definition

Aerospace Engineerin

Some typical solid propellant rocket motors

Typical Solid Propellant Rocket Motors (shortly referred to as Solid Rocket Motors; SRM's) are described with the purpose to form a database, which allows for comparative analysis and applications in practical SRM engineering.Spacecraft Systems EngineeringSpace EngineeringAerospace Engineerin

Some typical hybrid propellant rocket motors

Aerospace Engineerin

Development of a solar thermal thruster system

At the Delft University of Technology the use of solar radiation to heat a propellant to a high temperature is investigated as an alternative to resistance heating. The latter only allows for a solar power to heat conversion efficiency of about 25%, depending on the solar cells, whereas for solar heating 80% seems feasible. This paper addresses the theoretical and experimental investigations performed in the field of solar thermal propulsion at Delft University and more specific the solar thermal thruster development. The work performed includes the development of a theoretical model that assists the designer in the design and prediction of the performances of the solar thermal thruster. Also a demonstration solar thermal thruster has been developed and tested at different mass flow rates to verify the model. These tests have been performed using the Delft Aerospace Rocket Test Stand. Measurement parameters included thrust, propellant temperature, mass flow and pressure. In this paper we will present an overview of the theoretical model developed, the demonstration thruster as well as the test results. Finally, we present the main conclusions and recommendations related to the outcomes of the work.Space EngineeringAerospace Engineerin

Design, Simulation and Optimisation of a Low-Pressure Micro-Resistojet for Small Satellite Missions

Incorporating propulsion in small satellites is becoming a growing trend, due to its potential for enabling new and ambitious mission objectives. One of these objectives is formation flying, that will be pursued by TU Delft for the DelFFi mission as part of the larger QB50 project. For DelFFi, two identical spacecraft will use propulsion to allow for relative positioning. Due to the intrinsic limitations in mass, volume, power and propellant choice, pico-/nanosatellite propulsion poses different challenges when compared to larger spacecraft. The design of a MEMS (Micro Electro- Mechanical Systems) resistojet using water (ice) as propellant, operating at low pressures in the range of 50 to 200 Pa (below the vapour pressure of ice at temperatures below 270 K) will be described. The main results of a set of DSMC (Direct Simulation Monte Carlo) simulations performed with the open source dsmcFoam solver, showing the influence of geometry on thruster performance, in particular thrust and specific impulse, at a given input power will be presented. The low operating pressure allows for using the vapour pressure of ice as the only method of propellant feeding. The design presented in the paper will use few moving parts — one in the thruster and two or three in the propellant storage subsystem — and two heat inputs: one in the thruster and one to maintain the propellant temperature in the tank. The simulations, performed with various geometries and propellant storage conditions, show that the proposed design represents an alternative, low risk, micro-propulsion system suitable for small satellite missions, with the pressure inside the system never exceeding 600 Pa.Space Systems Egineerin

Numerical investigation of atomisation using a hybrid Eulerian-Lagrangian solver

This study investigates the potential of a newly released multi-phase solver to simulate atomisation in an air-blast type atomiser. The 'VOF-to-DPM' solver was used to simulate primary and secondary atomisation in an atomiser with a coaxial injector-like geometry. The solver uses a hybrid Eulerian/Eulerian-Lagrangian formulation with geometric transition criteria between the two models. In this study isothermal, non-reacting flow at room temperature was assumed. The primary focus was predicting Sauter mean diameter and droplet velocity data at a sampling plane downstream of the injector. The solver produces the expected data and predicts trends similar to those found in experimental measurements. The accuracy of the produced droplet diameters was roughly a factor 2 off compared to experiment. This is attributed primarily to mesh resolution. It was concluded that the solver has the potential to predict atomisation at a reasonable computational cost, but further study is needed to confirm its full capabilities.Accepted Author ManuscriptFluid MechanicsSpace Systems Egineerin

Does Systems Engineering in Space Projects Pay?

This paper attempts to answer the question whether it “pays” to apply Systems Engineering methods, tools and techniques within a space project. To this purpose a possible correlation has been investigated between the Systems Engineering effort applied within a number of space projects and the project result in terms of technical quality, cost and schedule. Use has been made of historical data derived from the results of Systems Engineering audits of projects, some recent audits performed along the same lines and assessments of project results in terms of technical quality, cost and schedule by the systems engineers involved in the projects. Basis for the audits is a checklist addressing 93 different aspects of Systems Engineering in the field of requirements, concept design, design & development, verification and technical management. In total nine data sets related to six projects in the industrial and the academic world were used. Although the data obtained are rather “noisy” there appears to be a clear positive correlation between the SE effort applied and the project result. It appears also that the positive effects mainly show up in the cost and schedule results of the project, the technical quality of the project result being generally of a rather satisfactory level. Examining the results in detail the Systems Engineering effort in the field of requirements, design & development and technical management has the strongest correlation with the project result. The effort in the field of (concept) design and verification shows a less strong correlation. The data have been “refined” by deleting the projects that were most strongly influencing the correlation in a positive sense. The overall results remained, however, the same. An overview is given of those aspects generally receiving little attention in the Systems Engineering effort. Further analysis of these results will be the subject of a follow-on study.Space EngineeringAerospace Engineerin