Propulsion Architecture Research Articles

Opportunities and challenges for distributed propulsion and boundary layer ingestion

Purpose – The performance benefits of boundary layer ingestion (BLI) in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by numerous studies. Therefore, it is well known that increased inlet flow distortion due to BLI can dramatically reduce these benefits. In this context, a methodology that enables the assessment of different propulsion architectures, whilst accounting for these aerodynamic integration issues, is studied in this paper. Design/methodology/approach – To calculate the effects of BLI-induced distortion, parametric and parallel compressor approaches have been implemented into the propulsion system analysis. The propulsion architectures study introduces the concept of thrust split between propulsors and main engines and also examines an alternative propulsor configuration. In the system analysis, optimum configurations are defined using thrust-specific fuel consumption as figure of merit. Findings – For determined operating conditions, t...

Computational design of S-Duct intakes for distributed propulsion

Purpose The purpose of this paper is to identify efficient methods and tools for the design of distributed propulsion architectures.

Propulsion System Design of a Battery Electric Vehicle

Governments all around the world are mandating a greater level of vehicle electrification due to environmental and energy concerns. There are different levels of electrification in vehicles starting from mild hybrid to full battery electric vehicle (EV). These increasing levels of electrification result in rising levels of gasoline displacement with electricity and a subsequent improvement of fuel economy and reduction in emissions. Hybrids and their variants are being introduced. However, a full electrification of the vehicle is widely believed to be the future in addressing the above issues. General Motors (GM) has its own strategy for powertrain electrification, which includes a wide range of propulsion architectures from light hybrid systems, such as the eAssist, to fully electric systems, such as the Chevrolet Spark EV. The Spark EV has been introduced as a key part of GM?s overall strategy for powertrain electrification.

Fundamental Architecture and Analysis of an Antimatter Ultra-Intense Laser Derived Pulsed Space Propulsion System

Antimatter has been generated in large quantities by the Lawrence Livermore National Laboratory Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately 1020W/cm2 with pulse durations of roughly 1ps. With the Titan laser incident on a high atomic number target, such as gold, antimatter on the scale of 2 × 1010 positrons are generated. Roughly 90% of the generated positrons are ejected anisotropic and aft to the respective target. The mechanisms for the laser-derived positron antimatter generation involve electron interaction with the nuclei based on bremsstrahlung photons that yield electron-positron pairs as a consequence of the Bethe-Heitler process, which predominates the Trident process. Given the constraints of the current and near future technology space, a pulsed space propulsion configuration is advocated for antimatter derived space propulsion, similar in concept to pulsed radioisotope propulsion. Antimatter is generated through an ultra-intense laser on the scale of a Titan laser incident on a gold target and annihilated in a closed chamber, representative of a combustion chamber. Upon reaching a temperature threshold, the closed chamber opens, producing a pulse of thrust. The implication of the pulsed space propulsion antimatter architecture is that the energy source for the antimatter propulsion system can be decoupled from the actual spacecraft. In contrast to conventional chemical propulsion systems, which require storage of its respective propulsive chemical potential energy, the proposed antimatter propulsion architecture may have the energy source at a disparate location from the spacecraft. The ultra-intense laser could convey its laser energy over a distance to the actual spacecraft equipped with the positron antimatter pulsed space propulsion system. Hydrogen is considered as the propulsive fluid, in light of its low molecular weight. Fundamental analysis is applied to preliminarily define the performance of the positron antimatter derived pulsed space propulsion system. The fundamental performance analysis of the antimatter pulsed space propulsion system successfully reveals the architecture is viable for further evaluation.

Highly reusable space transportation: Advanced concepts and the opening of the space frontier

Revolutionary changes in how cargo and people are transported into space are needed to enable the affordable development and exploration of space in the 21st century. Diverse efforts to achieve major, but incremental Earth-to-orbit (ETO) improvements in the relatively near term have been undertaken in recent years in the US, including the Department of Defense evolved expendable launch vehicle system development project. The NASA-industry reusable launch vehicle (RLV) program is addressing this challenge for the mid-term. The RLV program will validate the technology to enable industry to develop all-rocket reusable launch systems that can deliver payloads from the current Civil Needs Data Base in the 20,000–40,000 pounds class and smaller to low Earth orbit (LEO) at costs of approximately $1000–$2000 per pound. This represents a factor of 5 (or more) reduction below existing launch services. This “next generation” improvement in launch capability is a vital element of the US National Space Transportation policy for current and planned government and commercial payloads. The longer-term challenge is also being addressed. During 1995–1997, NASA conducted the highly reusable space transportation (HRST) study project to address the longer-term challenge: how to achieve an additional factor of 10 reduction in launch costs—to approximately $100–$200 per payload pound to LEO—thus enabling a revolutionary expansion of space activity and enterprise. The HRST study has identified a “grand strategy” for achieving these cost goals, based on pursuing a revolutionary advance in main propulsion architectures and technology for ETO systems to enable a dramatic improvements in subsystem operability. The HRST study has examined diverse approaches, including combination propulsion systems, combined cycle propulsion, launch assist systems, and revolutionary rocket propulsion. An integrated assessment has been conducted, including both the concepts defined as part of the study as well as past concepts. This assessment suggests that the cost goals of HRST are achievable within the next 10–20 years if appropriate technology investments are pursued. This paper provides a summary report on the results and findings of the HRST study project.