Exploration of Hybrid Electric Propulsion in Regional Aircraft

Flight Performance and Propulsio

Plasmas for Transition Delay

This paper describes the experimental investigation of the properties of Dielectric Barrier Discharge (DBD) actuators aimed at transition delay techniques. A wide range of geometrical configurations are tested as well as several electrical operational conditions. For the majority of the measurements statistical data for the induced flow field are obtained and for a limited selection of actuators, high sample-rate time resolved measurements are also conducted. All measurements are made in still flow in order to eliminate free-stream effects on the induced velocities. Results show the formation of a thin near-wall jet which could be used as a flow control device.Aerodynamics & Wind EnergyAerospace Engineerin

Flow separation control by off surface elements

Comparative wind tunnel experiments were performed on passive flow separation control on a at plate model equipped with a flap. The purpose of these tests was to investigate the flow control capabilities of off-surface mounted elements. A comparison was made of delta-shaped vortex generators of 1 to 1/3 boundary layer height and cylinders close to the wall. Surface pressure as well as PIV measurements were performed to investigate the influence of the layout of the VGs as well as the diameter of the cylinder and the position of the elements. The results showed that the off-surface devices performed better than the on-surface VGs for the fully separated case, and were equally good in improving the state of boundary layer that is on the verge of separation. It was also found that the off-surface devices could be positioned over a wider range with respect to the separation point. The experiments furthermore indicated that for the optimum cylinder configuration the vortex shedding frequency was consistent with the frequencies found in literature on periodic flow excitation.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin

Automatic classification of municipal call data for quantitative urban drainage system analysis

Flooding in urban areas can be caused by heavy rainfall, improper planning or component failures. Quantification of these various causes to urban flood probability supports prioritisation of flood risk reduction measures. In many cases, a lack of data on flooding incidents impedes quantification of probability and risk. In the proposed paper we use municipal call data that describe citizens’ observations of urban flooding incidents to quantify flood probabilities in a quantitative fault tree analysis. Given the unstructured nature of call information, calls are first assigned to classes that correspond with causes of flooding as represented in the fault tree. Since manual classification of calls is very timeconsuming, pattern recognition routines are used to automatically classify the call data. The aim of this study is to assess whether by automatic classification of citizen’s calls, sufficient accuracy can be obtained to allow for use of the results in quantitative risk analysis. This is illustrated by application of automatic classification results in a quantitative fault tree analysis for urban flooding, for two cases with datasets of approximately 6000 calls. The results show that straightforward automatic classification routines can reach error rates below 20%. Largest classification errors occur for small classes, where few data are available to train the classifiers. Automatic classification errors lead to small deviations in the outcomes of quantitative fault tree analysis. Still, conclusions about the ranking of contributions to urban flooding that are to be drawn from fault tree analysis, remain intact.Water ManagementCivil Engineering and Geoscience

Experimental Study on the Body Force Field of Dielectric Barrier Discharge Actuators

An experimental investigation on thrust and body force of Dielectric Barrier Discharge (DBD) /plasma actuators aimed at low power flow control applications is presented. A parametric study on thrust is conducted for a wide range of geometrical configurations as well as several electrical operational conditions. Direct measurements of the induced thrust are taken using a highly sensitive load cell. Simultaneous readings of current and voltage are also performed, providing the power consumption. Furthermore a novel technique for determination of the spatial distribution of the body-force is proposed, developed and tested. The technique involves the use of a high-speed PIV system to resolve all terms of the Navier-Stokes equation representation of the flow field including body force. Results reveal the existence of an explicit relation between voltage, thrust and consumed power. Furthermore the influence of the geometrical configuration of the actuator on the thrust is shown. The body force obtained with the proposed technique agrees well with the thrust measurements.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin

Gemeente Breda zet stedelijke wateropgave op de kaart

Water ManagementCivil Engineering and Geoscience

A Thrust-Elevator Interaction Criterion for Aircraft Optimal Longitudinal Control

The aim of this research is to investigate the combined use of throttle and aerodynamic control vanes for aircraft optimal control. A new disruptive aircraft configuration concept is presented, featuring control vanes downstream of two rear-mounted ducted propellers. The aerodynamic interaction between the horizontal vane and the throttle is analyzed in the scope of a longitudinal control study. A static criterion is proposed to discern the efficiency of the interaction, with respect to a generic pitch command. A traditional control allocation logic is used to exploit the throttle as a secondary pitch effector, and a modified version based on the interaction criterion is proposed; its behavior is tested through an open-loop design space exploration of actuator time constants and effectors prioritization weights. A flexible control system architecture is designed to compare the aircraft closed-loop response in conjunction with a phugoid damper loop. Results show that the best tracking performance is obtained with pilot commands allocated to the elevator, and phugoid damper commands to both elevator and throttle. The traditional allocation method achieves the best tracking performance at the expense of the largest control effort. The modified allocation alleviates the effort while still achieving better performance than the non-coupled control.Flight Performance and Propulsio

Decision-tree analysis of factors influencing rainfall-related building structure and content damage

Water ManagementCivil Engineering and Geoscience

A spatial analysis of rainfall damage data using c-band weather radar images

Intense rainfall may locally cause considerable damage in cities, e.g. because of sewer floods. A better understanding of relationships between rainfall characteristics and rainfall-related damage can help insurers and flood authorities to respond more adequately to rainfall extremes. This paper aims to study to what extent weather radars can be helpful to predict damage locations and characteristics. For the Netherlands, damage data were analysed based on daily insurance records. A database of C-band radar images was used to extract characteristics of rainfall events. These characteristics were linked to various damage statistics at district level and per day. Results are based on the 150 days with largest damage amounts nationwide. Rainfall and damage locations clearly showed similar spatial patterns when visualized on maps, particularly for the case maximum hourly rainfall intensity and rainfall volume. Through linear regression with log-transformed damage variables, highest correlation was found between claim ratio and maximum hourly rainfall intensity (r=0.38). The average damage per claim does not show any significant correlation with rainfall variables, except a weak relationship with maximum hourly rainfall intensity (r=0.12). This means that more intense rainfall mainly affects the number of households claiming damage, while it hardly influences the amount of damage per individual household.Water ManagementCivil Engineering and Geoscience

A statistical analysis of insurance damage claims related to rainfall extremes

In this paper, a database of water-related insurance damage claims related to private properties and content was analysed. The aim was to investigate whether the probability of occurrence of rainfall-related damage was associated with the intensity of rainfall. Rainfall data were used for the period of 2003–2009 in the Netherlands based on a network of 33 automatic rain gauges operated by the Royal Netherlands Meteorological Institute. Insurance damage data were aggregated to areas within 10-km range of the rain gauges. Through a logistic regression model, high claim numbers were linked to maximum rainfall intensities, with rainfall intensity based on 10-min to 4-h time windows. Rainfall intensity proved to be a significant damage predictor; however, the explained variance, approximated by a pseudo-R2 statistic, was at most 34% for property damage and at most 30% for content damage. When directly comparing predicted and observed values, the model was able to predict 5–17% more cases correctly compared to a random prediction. No important differences were found between relations with property and content damage data. A considerable fraction of the variance is left unexplained, which emphasizes the need to study damage generating mechanisms and additional explanatory variables.Water ManagementCivil Engineering and Geoscience