An integrated methodology to assess the operational and environmental performance of a conceptual regenerative helicopter

This paper aims to present an integrated multidisciplinary simulation framework, deployed for the comprehensive assessment of combined helicopter powerplant systems at mission level. Analytical evaluations of existing and conceptual regenerative engine designs are carried out in terms of operational performance and environmental impact. The proposed methodology comprises a wide-range of individual modeling theories applicable to helicopter flight dynamics, gas turbine engine performance as well as a novel, physics-based, stirred reactor model for the rapid estimation of various helicopter emissions species. The overall methodology has been deployed to conduct a preliminary trade-off study for a reference simple cycle and conceptual regenerative twin-engine light helicopter, modeled after the Airbus Helicopters Bo105 configuration, simulated under the representative mission scenarios. Extensive comparisons are carried out and presented for the aforementioned helicopters at both engine and mission level, along with general flight performance charts including the payload-range diagram. The acquired results from the design trade-off study suggest that the conceptual regenerative helicopter can offer significant improvement in the payload-range capability, while simultaneously maintaining the required airworthiness requirements. Furthermore, it has been quantified through the implementation of a representative case study that, while the regenerative configuration can enhance the mission range and payload capabilities of the helicopter, it may have a detrimental effect on the mission emissions inventory, specifically for NOx (Nitrogen Oxides). This may impose a trade-off between the fuel economy and environmental performance of the helicopter. The proposed methodology can effectively be regarded as an enabling technology for the comprehensive assessment of conventional and conceptual helicopter powerplant systems, in terms of operational performance and environmental impact as well as towards the quantification of their associated trade-offs at mission level. Ali Fakhre, Ioannis Goulos, Vassilios Pachidis School of Engineering, Energy, Power and Propulsion Division, Cranfield University, Cranfield, Bedford, MK43 0AL, UK [email protected] The Aeronautical Journal, 2015, Vol 119, Issue 1211, pp1-24 Published by Cambridge University Press. This is the Author Accepted Manuscript. This article may be used for personal use only. The final published version (version of record) is available online at 10.1017/S0001924000010253. Please refer to any applicable publisher terms of use

Improvements in the rotorcraft fuel economy and environmental impact through multiple-landing mission strategy

This paper presents an integrated rotorcraft multidisciplinary simulation framework, deployed for the comprehensive assessment of combined rotorcraft–powerplant systems performance at mission level. The proposed methodology comprises a wide-range of individual modelling theories applicable to rotorcraft performance and flight dynamics, gas turbine engine performance, and estimation of gaseous emissions (i.e. nitrogen oxides, NOx). The overall methodology has been deployed to conduct a comprehensive mission level feasibility study for a twin-engine light (TEL) rotorcraft, modeled after the Airbus Helicopters Bo105 configuration operating on a multiple-landing flying (MLF) mission approach compared to rotorcraft employing a conventional flying (CF) mission approach. The results of the analyses allow mission level assessment of the both aforementioned approaches for a wide-range of useful payload (UPL) values, mission range as well as mission level outputs (e.g. fuel burn, mission time, and gaseous emissions i.e. NOx). Furthermore, evaluation of engine cycle parameters (i.e. overall pressure ratio (OPR), turbine entry temperature (TET), and engine mass flow) are also carried out with respect to both approaches. The results acquired through the parametric analyses suggest that the MLF mission approach has the potential to significantly reduce rotorcraft mission fuel burn as well as gaseous emission (i.e. NOx). It has also been established through the acquired results that rotorcraft employing the MLF mission approach requires lower engine operating power throughout the entire mission duration, and therefore operates on a relatively lower engine OPR, combustor entry temperature, mass flow, rotational speed, and the TET compared to rotorcraft employing CF mission approach. It is emphasized that such operation of the engine can potentially improve the rate at which the engine components (i.e. compressor, combustor, and turbine) may deteriorate, thus the MLF mission approach can potentially provide further benefit in terms of engine maintenance and overall engine life. Finally it has been emphasised that the mission total range is a critical parameter in determining the level of benefit that can be attained from the employment of MLF mission approach

Evaluation of component level degradation in the Boeing 737-800 air cycle machine

An aircraft is composed of several highly integrated and complex systems that enable it to deliver safe and comfortable flight. Its functionality is therefore strongly dependent on the safe operation of these systems within their designed optimal efficiencies. The air cycle machine (ACM) is a subsystem of the pressurized air conditioner (PACK) system, its key function is to enable refrigeration of the air in order to comply with the wide range of cabin environment requirements for maintaining aircraft safety and passenger comfort. The operation of the ACM is governed by the PACK control system which can mask degradation in its component during operation until severe degradation or failure results. The required maintenance is then both costly and disruptive. The ACM has been reported as one of the most frequently replaced subsystem and has been therefore reported as a major driver of unscheduled maintenance by the operators. This paper aims to investigate the component level degradation in the ACM at various severities and quantify the impact of its performance characteristics and associated interdependencies at PACK system level. In this paper, Cranfield University’s in-house environmental control system (ECS) simulation framework called simscape ECS simulation under all conditions (SESAC) has been implemented to evaluate degradation in the ACM components in a representative Boeing 737-800 aircraft PACK model. The fault modes of interest are those highlighted by the operators and correspond to the ACM compressor, turbine, and interconnecting mechanical shaft efficiency degradation. Simulation results, in terms of temperature, pressure, and mass flow at various degradation severities, are presented and discussed for each component at PACK system level. The acquired results suggest that, for all three fault modes, the PACK controller can compensate for an ACM degradation severity of up to 20%, allowing the PACK to sustain the delivery of the demanded temperature and mass flow. For degradation severity of above 20%, the PACK is able to deliver the demanded temperature with a substantially reduced mass flow. This has a significant impact on the PACK’s ability to meet the cabin demand efficiently. The methodology reported and the findings conceived to serve as an enabler toward formulating an effective PACK fault diagnostics and condition monitoring solution at system level, and fault reasoning at vehicle level

A review of model based and data driven methods targeting hardware systems diagnostics

System health diagnosis serves as an underpinning enabler for enhanced safety and optimized maintenance tasks in complex assets. In the past four decades, a wide-range of diagnostic methods have been proposed, focusing either on system or component level. Currently, one of the most quickly emerging concepts within the diagnostic community is system level diagnostics. This approach targets in accurately detecting faults and suggesting to the maintainers a component to be replaced in order to restore the system to a healthy state. System level diagnostics is of great value to complex systems whose downtime due to faults is expensive. This paper aims to provide a comprehensive review of the most recent diagnostics approaches applied to hardware systems. The main objective of this paper is to introduce the concept of system level diagnostics and review and evaluate the collated approaches. In order to achieve this, a comprehensive review of the most recent diagnostic methods implemented for hardware systems or components is conducted, highlighting merits and shortfalls

Simultaneous Determination of Binary Mixture of Estradiol and Progesterone Using Different Spectrophotometric Methods

    أربع تقنيات طيفية مشتقة سريعة ودقيقة وبسيطة للغاية تم استخدامها  من أجل التقدير الكمي للمزيج الثنائي من استراديول والبروجسترون المصنّعة على شكل كبسولة. الطريقة الأولى هي قياس الصفرى للمشتق الأول تم اكتشاف السعات المشتقة عند طول موجة عبور صفرى239.27 و292.51 نانوميتر لتقدير استراديول و 249.19 نانوميتر للبروجسترون. الطريقة الثانية هى الطرح النسبي يتم التقدير البروجسترون عند 240 نانوميتر بعد طرح التداخل الذى يمارسه استراديول. الطريقة الثالثة هى طرح السعة المعدلة تم انشاؤه بأستخدام التحليل الطيفى المشتق والتلاعب الرياضي. الطريقة الرابعة هي تقنية نسبة الأمتصاص تم قياس الأمتصاصية لكلا الدواءين عند طولين موجيين نقطة الأمتصاص متساوية 2601=λ ونقطة امتصاص2402=λ لبروجسترون ويتم حساب التراكيز النهائية بواسطة معادلة Q. منحنى المعايرة خطي من 140 – 5 و 32 – 2 ميكرو غرام /مل لاستراديول وبروجسترون على التوالى. تم اختبار انتقائية التقنيات المقترحة بأستخدام توليفات تركيبة تم ا إنشاؤها فى المختبر وتم تقيمها بأستخدام طريقة الإضافة القياسية. بأستخدام ANOVAأحادى الأتجاه  تمت مقارنة مخرجات الطرق المقترحة ولم تضهرالنتيجة أي فروق ذات دلالة احصائية بين التقنيات المقترحة.Four rapid, accurate and very simple derivative spectrophotometric techniques were developed for the quantitative determination of binary mixtures of estradiol (E2) and progesterone (PRG) formulated as a capsule. Method I is the first derivative zero-crossing technique, derivative amplitudes were detected at the zero-crossing wavelength of 239.27 and 292.51 nm for the quantification of estradiol and 249.19 nm for Progesterone. Method II is ratio subtraction, progesterone was determined at λmax 240 nm after subtraction of interference exerted by estradiol. Method III is modified amplitude subtraction, which was established using derivative spectroscopy and mathematical manipulations. Method IIII is the absorbance ratio technique, absorbance of both medicines was measured at two wavelengths λ1= 260, -absorptive point and λ2=240max of progesterone. The Q equations were used to calculate the final concentrations. The calibration curve is linear from 5.0–140 and 2.0–32.0 µg/ml for estradiol and progesterone respectively. The proposed techniques' selectivity was tested using synthetic combinations created in the lab and assessed using the standard addition method. Using one-way ANOVA, the outputs of the proposed ways were compared, and the result showed no significant differences between the proposed techniques

Optimized powerplant configurations for improved rotorcraft operational performance

This paper presents an integrated multidisciplinary rotorcraft design and optimization framework, deployed for the design and assessment of a conceptual rotorcraft powerplant configuration at mission level. The proposed approach comprises a wide-range of individual modeling theories applicable to rotorcraft flight dynamics, gas turbine engine performance and weight estimation as well as a novel physics-based, stirred reactor model for the rapid estimation of gas turbine gaseous emissions. A novel Single-Objective and Multi-Objective Particle Swarm Optimizer is coupled with the aforementioned integrated rotorcraft multidisciplinary design framework. The combined approach is applied to the multidisciplinary design and optimization of a reference Twin Engine Light civil rotorcraft modeled after the Eurocopter Bo105 helicopter, operating on representative mission scenario. Through the application of Single-Objective optimization, optimum engine design configurations are acquired in terms of mission fuel consumption, engine weight and gaseous emissions at constant technology level. Multi-Objective studies are carried out in order to quantify the optimum interrelationship between mission fuel consumption and gaseous emissions for the representative Twin Engine Light rotorcraft operation and a variety of engine configurations. The proposed approach essentially constitutes an enabler in terms of focusing the multidisciplinary design of rotorcraft powerplants to realistic, three-dimensional operations and towards the realization of associated engine design tradeoffs at mission level

A review of aircraft auxiliary power unit faults, diagnostics and acoustic measurem

The Auxiliary Power Unit (APU) is an integral part of an aircraft, providing electrical and pneumatic power to various on-board sub-systems. APU failure results in delay or cancellation of a flight, accompanied by the imposition of hefty fines from the regional authorities. Such inadvertent situations can be avoided by continuously monitoring the health of the system and reporting any incipient fault to the MRO (Maintenance Repair and Overhaul) organization. Generally, enablers for such health monitoring techniques are embedded during a product's design. However, a situation may arise where only the critical components are regularly monitored, and their status presented to the operator. In such cases, efforts can be made during service to incorporate additional health monitoring features using the already installed sensing mechanisms supplemented by maintenance data or by instrumenting the system with appropriate sensors. Due to the inherently critical nature of aircraft systems, it is necessary that instrumentation does not interfere with a system's performance and does not pose any safety concerns. One such method is to install non-intrusive vibroacoustic sensors such that the system integrity is maintained while maximizing system fault diagnostic knowledge. To start such an approach, an in-depth literature survey is necessary as this has not been previously reported in a consolidated manner. Therefore, this paper concentrates on auxiliary power units, their failure modes, maintenance strategies, fault diagnostic methodologies, and their acoustic signature. The recent trend in APU design and requirements, and the need for innovative fault diagnostics techniques and acoustic measurements for future aircraft, have also been summarized. Finally, the paper will highlight the shortcomings found during the survey, the challenges, and prospects, of utilizing sound as a source of diagnostics for aircraft auxiliary power units

Multi-objective optimization of a regenerative rotorcraft powerplant: quantification of overall engine weight and fuel economy

A computationally efficient and cost effective simulation framework has been implemented to perform design space exploration and multi-objective optimization for an advanced regenerative rotorcraft powerplant configuration at mission level. The proposed framework is developed by coupling a comprehensive rotorcraft mission analysis code with a design space exploration and optimization package. The overall approach is deployed to design and optimize the powerplant of a reference twin-engine light rotorcraft, modelled after the Bo105 helicopter, manufactured by Airbus Helicopters. Firstly, a sensitivity analysis of the regenerative engine is carried out to quantify the interrelationship between the engine thermodynamic cycle design parameters, engine weight, and overall mission fuel economy. Secondly, through the execution of a multi-objective optimization strategy, a Pareto front surface is constructed, quantifying the optimum trade-off between the fuel economy offered by a regenerative engine and the associated weight penalty. The optimum sets of cycle design parameters obtained from the structured Pareto front suggest that the employed heat exchanger effectiveness is the key design parameter affecting the engine weight and fuel efficiency. Furthermore, through quantification of the benefits suggested by the acquired Pareto front, it is shown that, the fuel economy offered by the simple cycle rotorcraft engine can be substantially improved with the implementation of regeneration technology, without degrading the payload-range and airworthiness (One- Engine-Inoperative) requirements of the rotorcraft

Signal processing of acoustic data for condition monitoring of an aircraft ignition system

Degradation of the ignition system can result in startup failure in an aircraft’s auxiliary power unit. In this paper, a novel acoustics-based solution that can enable condition monitoring of an APU ignition system was proposed. In order to support the implementation of this research study, the experimental data set from Cranfield University’s Boeing 737-400 aircraft was utilized. The overall execution of the approach comprised background noise suppression, estimation of the spark repetition frequency and its fluctuation, spark event segmentation, and feature extraction, in order to monitor the state of the ignition system. The methodology successfully demonstrated the usefulness of the approach in terms of detecting inconsistencies in the behavior of the ignition exciter, as well as detecting trends in the degradation of spark acoustic characteristics. The identified features proved to be robust against non-stationary background noise, and were also found to be independent of the acoustic path between the igniter and microphone locations, qualifying an acoustics-based approach to be practically viable

Understanding the role of sensor optimisation in complex systems

Complex systems involve monitoring, assessing, and predicting the health of various systems within an integrated vehicle health management (IVHM) system or a larger system. Health management applications rely on sensors that generate useful information about the health condition of the assets; thus, optimising the sensor network quality while considering specific constraints is the first step in assessing the condition of assets. The optimisation problem in sensor networks involves considering trade-offs between different performance metrics. This review paper provides a comprehensive guideline for practitioners in the field of sensor optimisation for complex systems. It introduces versatile multi-perspective cost functions for different aspects of sensor optimisation, including selection, placement, data processing and operation. A taxonomy and concept map of the field are defined as valuable navigation tools in this vast field. Optimisation techniques and quantification approaches of the cost functions are discussed, emphasising their adaptability to tailor to specific application requirements. As a pioneering contribution, all the relevant literature is gathered and classified here to further improve the understanding of optimal sensor networks from an information-gain perspective