Mitsubishi Heavy Industries (Italy)

View Video Presentation: https://doi.org/10.2514/6.2022-1440.vid Engineering analysis using finite element models of complex aerospace structural components is computationally expensive and consists of multiple inputs and outputs. The analysis becomes more demanding when the system inputs and outputs vary over space and time, and the problem becomes very high-dimensional. Surrogate models are often employed to replace the physics-based model to achieve computational efficiency in analyses such as uncertainty quantification and optimization. This report develops a surrogate modeling approach for such high-dimensional problems. Several methods for reducing the output dimension are explored and compared, namely, singular value decomposition (SVD), random projection (RP), and randomized SVD; and variance-based sensitivity analysis and active subspace discovery are considered for input dimension reduction. The combination of dimension reduction methods that provide the best accuracy and computational effort are identified. This is followed by the construction of Gaussian process surrogate models or machine learning (ML) models in the low-dimensional space. The errors in the surrogate model prediction, both in the low-dimensional latent space and the high-dimensional original space, are quantified. Two examples, aircraft fuselage panel and gas turbine engine, are used to analyze the effectiveness of the proposed approach.

The Centrifuge Accommodation Module (CAM) is designed to be one of the modules of the International Space Station (ISS) for performing on-orbit science experiments over an extended period of time. The common cabin air assembly (CCAA) is utilized as the hardware for air temperature and humidity control (THC) for the CAM module cabin. The CCAA unit contains a variable speed fan, heat exchanger, temperature control valve, water separator, temperature sensor, and electrical interface box. A temperature and humidity simulation model was developed to perform the THC analysis for the CCAA unit inside the CAM. This model applies both fixed control volume and a quasi-steady-state approach for computing critical information for evaluating/assessing CCAA system performance and capabilities. The results of the CAM module cabin air temperature and humidity control analysis for both nominal and peak heat load conditions, taking into account the coolant flow rate, are described in detail and presented in this paper. It is believed that the cabin air temperature and humidity results can provide essential technical support to verify CCAA system capability for the CAM module operation on orbit.

The H-II Transfer Vehicle (HTV), designed and built in Japan, is one of unmanned cargo transfer spacecrafts and the HTV-1 was launched in September, 2009 as a first flight. The HTV-1 was docked to the ISS a week after the launch and had been attached to the ISS for 45 days to carry cargoes to the ISS and re-entried November, 2009. The first mission was successful and that was a big step as a major milestone in the history of Japanese aerospace development. In this paper, the HTV thermal control architecture and verification results are summarized firstly. Also, flight data evaluation, flight operation and road to the HTV-2, second mission planned in January, 2011, from the standpoint of thermal control system (TCS) are described. It was confirmed that the cycle of design, manufacturing and operation for the HTV-1 worked well and we have started to prepare for the HTV-2.

View Video Presentation: https://doi.org/10.2514/6.2023-4479.vid The objectives of this study are to clarify flow features and noise sources around inboard slat-tip region and then to propose efficient methods to reduce the noise. In this study, numerical simulations were performed to investigate the flowfield and noise sources around a realistic inboard slat-tip using a CFD model of a regional jet type aircraft. The results clarified the three-dimensional flow features and three potential noise sources near the inboard slat-tip. Three noise reduction methods proposed to reduce the potential noise sources and their combination were evaluated through numerical simulations and a wind tunnel test: A rounded-tip, a blade-seal cut, and a fence bent forward. The effectiveness of each noise reduction method has been clarified through the wind tunnel test. It has been shown that even minor modifications to the inboard side-edge by the rounded-tip or fence bent forward have a noticeable impact on noise reduction around the inboard side-edges. The numerical simulations and wind tunnel test results have shown that the combination of the rounded-tip and the blade-seal cut is also effective to reduce the noise around the inboard slat-tip.

The development duration of commercial aircraft has become longer than ever due to the increasing complexity of aircraft systems and new technologies. This longer duration increases exposure to changes in design inputs, such as requirements or product planning. This paper proposes an integrated commercial aircraft conceptual design process that utilizes the Set-Based Approach, analyses of various fidelities, and estimation methods suitable for new architectures to minimize the negative impacts caused by changes in design inputs. The proposed process takes advantage of the Convergent Design Process with the Set-Based Approach, which handles a large number of design candidates in parallel, thereby reducing the risk of design rework. Also, the fidelity of analyses is increased according to the required accuracy and speed as the design progresses. This process is enabled by three types of digital models: descriptive, analytical, and process models. It is applied to a case study of a 90-seat class commercial aircraft design. The results show that the proposed process gradually converges the design space, and that introducing high-fidelity analyses early in the design process reduces the risk of design rework.

CFD-based aeroelastic analysis has high accuracy to predict aeroelastic instability. To utilize this analysis in practical design process, it is important to validate the accuracy and identify the challenges by applying this analysis to practical geometry such as the wing with control surfaces. On the other hand, there are few studies about aeroelastic analysis targeted at such geometry. In this paper, two types of the CFD-based aeroelastic analysis were conducted to validate the accuracy and clarify the challenges to reveal the feasibility for handling the practical geometry: the Horizontal Tail (HT) flutter model consisting of the HT and the elevator, and the complete aircraft with control surfaces. In the analysis for the HT flutter model, the accuracy of the analysis was validated by comparing the flutter boundary with the wind tunnel test data. In the analysis for the complete aircraft with control surfaces, the challenges for the CFD-based aeroelastic analysis were identified; oscillated CFD mapped surfaces around noncontinuous modal shape and mesh quality degradation near gaps. To deal with them, two approaches were suggested; the mapping method which can generate smooth mapped CFD surfaces from noncontinuous mode shapes and the analysis approach which decreases mesh deformation by using regenerated deformed surface meshes. With these approaches, the CFD-based aeroelastic analysis at high dynamic pressure did not crash and the modal damping can be calculated from obtained modal displacement. They are effective to analyze about practical geometries stably with the CFD-based aeroelastic analysis.

In recent years, energy saving of the propulsion plant is progressing as environmental transformation which surround a LNG carrier. In addition to the conventional steam propulsion system, the medium-speed diesel engine in which the gas combustion which is superior in plant efficiency is possible is increasing. So, in our company, the reheat furnace which arranged the reheat burner was formed in the exhaust gas exit of the main boiler (with no reheat) of a conventional type as a boiler of a reheat system, and the structure which overheats reheat steam was developed by making a main boiler exhaust gas warm. Thereby, while forming steam temperature into high temperature and high pressure, it contributed to 15% of improvement in efficiency to the conventional steam propulsion plant by adopting a reheat cycle. At the running test in the real ocean space, these measures were able to prove the target performance of steam temperature.

In recent years, energy saving of the propulsion plant is progressing as environmental change which surround LNG carriers, and the vessel which carries the medium-speed dual fuel engine which is superior in plant efficiency to the conventional steam propulsion plant is increasing. So, in our company, the reheat furnace which arranged the reheat burnur was formed in the exhaust gas exit of the main boiler (with no reheat) of a conventional type as a boiler of a reheat system, and the structure which overheats reheat steam was developed by making a main boiler exhaust gas warm. Thereby, while forming steam temperature into high temperature and high pressure, it contributed to 15% of improvement in efficiency to the conventional steam propulsion plant by adopting a reheat cycle. At the runnig test in the real ocean space, these measures were able to prove the target performance of steam temperature.