Advancements in Designing, Producing, and Operating Off-Earth Infrastructure

Sending humans to the Moon and Mars in the near future requires appropriate infrastructure to support and subsequently sustain human activities. This includes infrastructure to shield from environmental conditions, generate energy, and facilitate mobility and communication. Construction of such infrastructure aims to use in-situ resources and reduce the use of supplies from Earth. The establishment and maintenance of the required infrastructure, equipment, and hardware involves the development of adequate manufacturing techniques, which can enable maximal use of the local resources. Those techniques can be based on processing of local materials into construction materials, extraction of useful elements from local materials or in combination with materials brought from Earth. The required manufacturing techniques address the range of needs for sustained human activities, from smaller scale manufactured items to large built structures. The design of such structures is associated with a number of space systems’ engineering challenges, ranging from the accurate definition of all resource budgets (mass, volume, power, data) to the design of the interfaces between all subsystems making use of these resources. The interplanetary spacecraft used to transport the required materials (and eventually, crew) from Earth to the final site would probably need to be designed ad-hoc for this specific application, given its peculiar mass and volume constraints, especially in case a reusable concept is adopted. Other engineering aspects involved in the design of the infrastructure systems include the selection of an appropriate power generation approach and the definition of the radiation environment in order to provide sufficient shielding to the habitats. This Spool CpA #4 issue investigates challenges of designing, engineering, constructing, operating, and maintaining off-Earth infrastructure

Cavitation and Flow Instabilities in a 3- Bladed Axial Inducer Designed by Means of a Reduced Order Analytical Model

The present paper illustrates the main results of an experimental campaign conducted using the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Alta S.p.A. The tests were carried out on the DAPAMITO inducer, a three-bladed axial pump designed and manufactured by Alta S.p.A. using a simplified analytical model for the prediction of geometry and noncavitating performance of typical space rocket inducers. The transparent inlet section of the facility was instrumented with several piezoelectric pressure transducers located at three axial stations: inducer inlet, outlet and the middle of the axial chord of the blades. At each axial station at least two transducers were mounted with given angular spacing in order to cross-correlate their signals for amplitude, phase and coherence analysis. However, probably because of the high value of the blade tip clearance, very few flow instabilities have been detected on the inducer, including: steady asymmetric cavitation caused by the different extension of the cavitating regions on the blades; cavitation surge at a frequency equal to 0.16 times the inducer rotational frequency; a higher-order axial phenomenon at 7.2 times the rotational frequency

Experimental Performance of a Tapered Axial Inducer: Comparison with Analytical Predictions

The present paper illustrates the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Alta S.p.A. for the characterization of the pumping and suction performance of a three-bladed, tapered-hub, variable-pitch inducer, indicated as DAPAMITO3. The test inducer has been sized and designed by means of the reduced order model recently developed at Alta S.p.A. for the definition of the geometry and the prediction of the non-cavitating performance of typical high-head space rocket inducers. The pumping performance of the inducer proved to be in good accordance with the model predictions. The effects of the blade tip clearance have been investigated and the corresponding performance degradation has been correctly predicted by means of a semi-empirical extension of the model. Finally, the effects of the working fluid temperature on both the non-cavitating and cavitating performance of the inducer have been analysed. At higher ..

Dialogues on Architecture

Dialogues on Architecture is a series of dialogues between researchers and practitioners, who are embracing the intellectual model of high technology and are involved in its advancement and application in architecture. Dialogue #4 focuses on the technology transfer between on- and off-Earth research and its impact on society, and in particular on industry and education. The dialogue takes place between Henriette Bier (HB), Paul Chan (PC), Advenit Makaya (AM), and Angelo Cervone (AC)

On the Preliminary Design and Performance Prediction of Centrifugal Turbopumps—Part 2

The ideal flow model for the preliminary design and performance prediction of radial turbopumps presented in the companion paper of the present volume (d’Agostino et al., 2017) is here interfaced with the calculation of the boundary layers inside the blade channels and other major forms of flow losses, with the aim of developing an effective tool for rapid parametric optimization of the machine performance and geometry under appropriate design constraints, such as assigned values of the specific speed, flow coefficient and blade solidity. A mixed-flow turbopump, with a six-bladed impeller, a vaneless diffuser, a single-spiral volute and nondimensional performance characteristics similar to those typically used in liquid propellant rocket engine feed systems, has been designed, parametrically optimized and manufactured in accordance with the indications of the present model. The pumping and suction performance of the machine have been determined in a series of tests in the Cavitating Pump Rotordynamic Test Facility (CPRTF). Under fully-wetted flow conditions the measured pumping characteristics of the machine (hydraulic head and efficiency as functions of the flow coefficient) proved to be in excellent agreement with the model predictions, thus successfully confirming the validity of the proposed model as an effective tool for rapid and efficient design of high-performance centrifugal turbopumps

A Reduced Order Model for Optimal Centrifugal Pump Design

A reduced order model for preliminary design and noncavitating performance prediction of radial turbopumps has been illustrated in a previous paper presented by the same authors. The model expresses the 3D incompressible, inviscid, irrotational flow through helical blades with slow axial variations of the pitch and backsweep by superposing a 2D cross-sectional axial vorticity correction to a fully-guided flow with axisymmetric stagnation velocity in the meridional plane. Application of the relevant governing equations yields a set of constraints for the axial evolution of the blade pitch and backsweep that allows for the closed form definition of the impeller geometry and flowfield in terms of a reduced number of controlling parameters. In turn, mass and momentum conservation are used to account for the mixing of the flow leaving the impeller and its coupling with 2D reduced order models of the flow in the diffuser (if any) and the volute, thus generating the information necessary for completing the geometric definition of the machine and for determining its ideal noncavitating performance in accordance with the resulting flowfield. In the present paper, the above ideal flow model has been interfaced with the calculation of boundary layers inside the blade channels and other major forms of flow losses, with the aim of developing an effective tool for rapid parametric optimization of the machine geometry and performance under appropriate design constraints such as target values of the specific speed, flow coefficient and impeller blading solidity

Towards the Use of Commercial-off-the-Shelf Small-Satellite Components for Deep-Space CubeSats: a Feasibility and Performance Analysis

The aim of this paper is to assess the feasibility of using currently available commercial-off-the-shelf (COTS) small-satellites components in deep-space scenarios, studying their applicability and performance. To evaluate the performances, an asteroid fly-by mission is briefly introduced, but several of the selection criteria and ideas can be extended to other deep space mission concepts. This particular mission scenario requires to follow three main trends: miniaturization, standardization and automation. For this reason the mission represents a good test bench scenario to analyze the products of the current small-satellites industry. Once the reference mission has been defined, the preliminary ΔV is computed and the micro-propulsion system is selected. Afterwards, for several satellite subsystems the requirements are compared with the expected performance of a set of small-satellite components currently available on the market. Once the most promising hardware solutions are identified, mass and volume budgets are defined. Subsequently, drawbacks and limits of using COTS components for deep-space exploration are highlighted, focusing on the readiness level of each subsystem. Finally, recommendations are given on what methods and hardware are needed in the near future to overcome the limiting factors and to allow deep-space exploration using low-cost CubeSats

High Mass Flux Tests on Catalytic Beds for H2O2 Monopropellant Thruster

The present paper illustrates the results of an experimental campaign carried out using LR-III-106 catalyst developed by ALTA S.p.A. in collaboration with the Chemical Department of Pisa University. The catalytic bed has been integrated into a hydrogen peroxide monopropellant thruster prototype and tested in ALTA’s Green Propellant Rocket Test Facility. Endurance tests on LR-III-106 catalyst had been already performed with the same thruster prototype at a lower mass flux (G≈12 kg/m^2 s): the bed was able to decompose up to 13 kg of 90% hydrogen peroxide, equivalent to 2500 s of thruster continuous operation, exhibiting C-Star efficiency higher than 95%. The tests reported in the present paper have been aimed at investigating the performance of the catalyst and the thruster with a mass flux increased up to 55 kg/m^2 s. The bed has shown high decomposition and propulsive efficiencies, well in excess of 90%. The cold start-up transient has been reduced to about 1 s, one..

Experimental Characterization of a 5 N Hydrogen Peroxide Monopropellant Thruster Prototype

In the framework of the LET-SME program funded by the European Space Agency, ALTA S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) jointly investigated the use of advanced catalytic beds on ceramic supports as a cost-effective alternative to metal screen reactors for the decomposition of high-concentration hydrogen peroxide in small monopropellant rockets. To this purpose ALTA S.p.A. designed and realized a reconfigurable test bench for the characterization of the operation and propulsive performance of small rocket thrusters. The present paper illustrates the experimental campaign carried out on a 5 N thruster prototype operating with two platinum catalysts on g− alumina supporting spheres, especially developed by ALTA in collaboration with the Chemistry and Industrial Chemistry Department of Pisa University, Italy. The results indicated that Pt/Al2 O3 is an effective catalyst combination for the decomposition of 87.5% propellant grade hydrogen peroxide, with good stability and performance comparable to silver screen beds of equal geometric envelope and operational conditions. Incomplete hydrogen peroxide decomposition and the onset of flow oscillations in the reactor were observed at the tested levels of bed loading, residence time and flow pressure. Thermal stresses due to the large temperature gradients occurring during the decomposition of high grade hydrogen peroxide (87.5% by weight) caused the ceramic pellets to break and the progressive occlusion of the bed. Based on the analysis of the test results, several ways to overcome these problems in future investigations have been tentatively identified, together with the necessary modifications to the present experimental set-up