<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJkYXRlaW4iIHZhbHVlPSJhbGwiIC8+PHBhcmFtIG5hbWU9InN1YmplY3Rsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJ0ZXJtc2xvZ2ljIiB2YWx1ZT0ib3IiIC8+PHBhcmFtIG5hbWU9ImxvY2F0aW9uIiB2YWx1ZT0iMCIgLz48L3BhcmFtcz48ZmlsdGVycz48ZmlsdGVyIGZpZWxkPSJpbmRleHRlcm1zIiB2YWx1ZT0iJnF1b3Q7QmxhZGUmcXVvdDsiIG9yaWdpbmFsX3ZhbHVlPSImcXVvdDtCbGFkZSZxdW90OyIgLz48L2ZpbHRlcnM+PHJhbmdlcyAvPjxzb3J0cz48c29ydCBmaWVsZD0icHVibGlzaGVkIiBvcmRlcj0iZGVzYyIgLz48L3NvcnRzPjxwZXJzaXN0cz48cGVyc2lzdCBuYW1lPSJyYW5nZXR5cGUiIHZhbHVlPSJwdWJsaXNoZWRkYXRlIiAvPjwvcGVyc2lzdHM+PC9zZWFyY2g+" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>On the performance of marine propeller in regular waves, Part II: Single Blade loads in rough sea states</title>
      <link>https://trid.trb.org/View/2710172</link>
      <description><![CDATA[This work continues the analysis of the single blade loads generated during motion in moderate waves investigated in Ortolani et al. (2024) (0.012<Hw/LPP<0.022) to rough waves (0.035<Hw/LPP<0.053) at the same moderate-to-medium speed (i.e., Froude number FN=0.17 and 0.25) and wave lengths λ=0.8, 1.0 and 1.6. Along the same lines of part I, the accuracy of the instantaneous measure, and its averaged mean and fluctuation in the propeller and wave cycle is assessed by uncertainty analysis and validated in contrast to thrust and torque obtained by standard set-up. The evolution of the loads and their correlation with the motion is inspected through a phenomenological perspective. In contrast to the analysis provided in Part I, the propeller hydrodynamics is affected by ventilation phenomena, that have been documented by means of qualitative flow visualization. The analysis shows how this mechanisms affects the evolution of the mean and fluctuating components of the single blade loads in the wave and propeller cycle. Together with the complementary Part I, the present study contributes to the establishment of a systematic, uncertainty-quantified reference dataset on wave-induced single-blade propeller loads over a broad range of realistic ship operating conditions.]]></description>
      <pubDate>Mon, 08 Jun 2026 15:48:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2710172</guid>
    </item>
    <item>
      <title>Comparison of time and frequency domain analysis of propeller loading noise</title>
      <link>https://trid.trb.org/View/2700550</link>
      <description><![CDATA[This study presents a unified analytical framework for investigating the acoustic pressure generated by rotating point forces, with particular emphasis on comparing time and frequency domain formulations. While both approaches yield consistent results, each offers distinct benefits: the time domain provides intuitive insight into the contributions of steady and unsteady loading, whereas the frequency domain facilitates modal decomposition and simplifies the analysis of periodic noise. The model represents uniformly spaced blades as point forces with axial, drag, and radial components. The force magnitude varies in time according to a Gaussian pulse, enabling investigation into the influence of time scale on propeller noise. This formulation is relevant to scenarios such as rotor systems experiencing periodic loading or isolated gust encounters. Both periodic and aperiodic cases are analysed in the time and frequency domains, allowing conditions for constructive and destructive inter-blade interference to be identified. The study also examines the advantages of each formulation. Time domain analysis provides a more intuitive interpretation of aperiodic phenomena but requires careful treatment of retarded time effects. In contrast, the frequency domain is well-suited to periodic problems and naturally aligns with modal acoustic models, though it may obscure certain inter-blade interaction mechanisms. Collectively, these insights advance the understanding of rotor noise generation and its spatial characteristics in installed configurations.]]></description>
      <pubDate>Wed, 20 May 2026 09:10:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2700550</guid>
    </item>
    <item>
      <title>Determination of Loads in the Ultralight Helicopter Blades</title>
      <link>https://trid.trb.org/View/2470721</link>
      <description><![CDATA[The article describes research that was carried out on coaxial a single-seat ultralight helicopter Rotorschmiede VA-115 which is manufactured by German firm RS Helikopter GmbH. The purpose of the work was to determine the blades’ loads necessary for further blade fatigue analysis and ground bench tests. The methodology for the load determination consisted of deformation measurements using strain gauges in various flight modes from hovering to maximum speed flight, including climb, descent, acceleration, and braking. Ultralight helicopters occupy the smallest cost niche and, as a rule, full-fledged fatigue studies are not performed for such helicopters. The requirements for ultralight helicopters are also quite loyal, allowing them to pass such experiments. Analysis of the data shows that the amplitude of bending moments on the lower rotor is higher by 1.2 to 2 times the value on the upper rotor. The absolute maximum value of the bending moment is significantly greater at the minimum weight, although the oscillation amplitude becomes smaller. The presented data can be useful for designers of ultralight and UAV helicopters with teetering hinge rotors.]]></description>
      <pubDate>Fri, 27 Dec 2024 15:27:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2470721</guid>
    </item>
    <item>
      <title>On the performance of marine propeller in regular waves, Part I: Single Blade loads in moderate sea states</title>
      <link>https://trid.trb.org/View/2392889</link>
      <description><![CDATA[During navigation in waves, the mean and fluctuating components of the loads developed by marine propellers changes with respect to calm water condition, as a consequence of the motions that modify the viscous wave of the ship and wave induced velocities. The most critical consequence are the loss of propulsive efficiency, increase of propulsive power demand and increase of emissions that, with the introduction of the EEDI index, have increasingly become pivotal issues in ship design. Contextually, the exacerbation of side effects associated to propeller functioning (pressure pulses vibration and radiated noise) and the reduction fatigue life of the components of the propulsion system occur. The mitigation of all these effects can be achieved both by automatic control of the propulsion system and/or blade shape design. These issues demand a deeper knowledge of the propeller in waves than the usual, focused essentially on the total propulsive loads (propeller thrust and torque). This issue motivated a thorough experimental investigation at CNR-INM by means of measurements of single blade loads during self-propulsion in regular waves for a twin screw propulsive configuration. This paper is dedicated to the analysis and discussion of the single blade loads developed during navigation in moderate sea state (SS3 and SS4) at three different wave lengths (λ = 0.8, 1.0 and 1.6) and for two different Froude numbers (FN = 0.17 and 0.25).]]></description>
      <pubDate>Thu, 18 Jul 2024 10:49:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2392889</guid>
    </item>
    <item>
      <title>Mechanism analysis of propeller-ice contact and rapid prediction of ice loads</title>
      <link>https://trid.trb.org/View/2240408</link>
      <description><![CDATA[To facilitate the rapid prediction of propeller ice loads, as well as to aid in the assessment of strength and optimal design of ice-class propellers, a state-based peridynamic (PD) method was utilized for mechanism analysis of propeller-ice contact and ice-loads sensitivity analysis. Both critical bond-stretch (CS) and critical energy (CE) damage criteria were implemented to determine whether sea ice is damaged. A verification example and comparison were given for a milling test. The design space for the propeller section was evaluated to perform the sensitivity analysis of ice loads to airfoil geometry and milling angle of attack. Based on the sensitivity results, a rapid-prediction method for propeller ice loads was proposed. As the airfoil mills ice with a slight angle (smaller than 7°), the CE criterion is more suitable than the stretch criterion. It was found that, by sensitivity analysis, there is little difference in the magnitude of ice loads applied on different airfoils with varying camber and thickness distribution and maximum thickness. Only the change in the maximum camber will make a difference in the transversal ice load. A propeller ice-loads calculation example shows the feasibility and convenience of the proposed prediction method, the error of which is only 4.5% compared with the experimental value.]]></description>
      <pubDate>Fri, 06 Oct 2023 08:37:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2240408</guid>
    </item>
    <item>
      <title>An improved dynamic load-strength interference model for the reliability analysis of aero-engine rotor blade system</title>
      <link>https://trid.trb.org/View/1871775</link>
      <description><![CDATA[As the power source of an aircraft, aero-engine tends to meet many rigorous requirements for high thrust-weight ratio and reliability with the continuous improvement of aero-engine performance. In this paper, based on the order statistics and stochastic process theory, an improved dynamic load-strength interference (LSI) model was proposed for the reliability analysis of aero-engine rotor blade system, with strength degradation and catastrophic failure involved. In presented model, the “unconventional active” characteristic of rotor blade system, changeable functioning relationships and system-component configurations, was fully considered, which is necessary for both theoretical analysis and engineering application. In addition, to reduce the computation cost, a simplified form of the improved LSI model was also built for convenience of engineering application. To verify the effectiveness of the improved model, reliability of turbojet 7 engine rotor blade system was calculated by the improved LSI model based on the results of static finite element analysis. Compared with the traditional LSI model, the result showed that there were significant differences between the calculation results of the two models, in which the improved model was more appropriate to the practical condition.]]></description>
      <pubDate>Tue, 30 Nov 2021 10:24:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1871775</guid>
    </item>
    <item>
      <title>In-plane and single blade loads measurement setups for propeller performance assessment during free running and captive model tests</title>
      <link>https://trid.trb.org/View/1737606</link>
      <description><![CDATA[During ship actual operative condition, the inflow experienced by the propeller is different from the one adopted during design phase: moderate, tight or emergency manoeuvres and heavy sea are some of the conditions that could occur, which alter the flow to the propeller. The resulting inflow gives rise to a complex system of loads developed by the blades and the propeller, which can cause failures and damages. Moreover, these loads have a direct impact on the manoeuvring ability of the ship, because act to stabilize the ship. The quantification of these loads and the assessment of their origin with ship dynamics and wake is pivotal to optimize the propulsive performance of the ship, mitigate their undesirable effects and, ultimately, achieve a successful design. In order to move further step with respect to standard monitoring of propeller performance in model testing and obtain a more complete set of information for the validation of numerical solvers, two novel experimental setups that were implemented and successfully tested on two ship models, are described in this paper. The first one is tasked for the measurements of the in-plane loads developed by the propeller, while by the second one is devoted to measure the complete set of loads generated by a single blade.]]></description>
      <pubDate>Tue, 29 Sep 2020 09:58:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1737606</guid>
    </item>
    <item>
      <title>Performance of Isolated UAV Rotors at Low Reynolds Number</title>
      <link>https://trid.trb.org/View/1701150</link>
      <description><![CDATA[Vertical takeoff and landing vehicle platforms with many small rotors are gaining importance for small UAVs as well as distributed electric propulsion for larger vehicles. To predict vehicle performance, it must be possible to gauge interaction effects. These rotors operate in the less-known regime of low Reynolds number, with different blade geometry. As a first step, two identical commercial UAV rotors from a flight test program are studied in isolation, experimentally and computationally. Load measurements were performed in Georgia Tech’s 2.13 m × 2.74 m wind tunnel. Simulations were done using the RotCFD solver which uses a Navier-Stokes wake computation along with rotor-disc loads calculation using low-Reynolds number blade section data. It is found that in hover, small rotors available in the market vary noticeably in performance at low rotor speeds, the data converging at higher RPM and Reynolds number. This is indicative of the high sensitivity of low-Re rotor flows to minor geometrical differences/imperfections in the rotors. It requires proper handling in computations. CFD results show a higher deviation from the experimental thrust data at low rotor speeds. While thrust prediction comes close to the experiments at high rotor speed, matching torque prediction values within reasonable bounds is still a challenge.       ]]></description>
      <pubDate>Mon, 22 Jun 2020 17:53:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1701150</guid>
    </item>
    <item>
      <title>Validation of CFD simulations of the flow around a full-scale rowing blade with realistic kinematics</title>
      <link>https://trid.trb.org/View/1667829</link>
      <description><![CDATA[This article deals with the validation of the modelling and numerical simulation of a rowing stroke, by means of CFD. Simplified but realistic strokes were performed in a towing tank with a rotating arm and a real flexible oar. Those laboratory conditions are better controlled than those of in situ trials. An FSI procedure is developed to take into account the oar bending, which is essential in the physics of this flow. The results show that this numerical framework is able to reproduce qualitatively the real flow including the breaking of the free surface around the blade and the transport of the air cavity behind it. The profiles of forces are well reproduced, with propulsive forces overestimated by 5–12% for their maxima. The study also focuses on the computation of the uncertainties. It is highlighted that, even for this well-controlled experimental equipment, the uncertainties on the quantities of interest are of about 11%. In other words, the experimental uncertainty covers the numerical errors. So, this numerical modelling is validated and can be used for design and optimisation of blades and oars, or to contribute to the better understanding of the boat–oar–rower system and its dynamics.]]></description>
      <pubDate>Fri, 20 Dec 2019 16:24:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1667829</guid>
    </item>
    <item>
      <title>Numerical models to predict the performance of tidal stream turbines working under off-design conditions</title>
      <link>https://trid.trb.org/View/1601540</link>
      <description><![CDATA[As previously experienced by the wind industry, it is envisaged that tidal stream turbine blades will present misalignments or blade deformations over time as they are constantly working under harsh and highly unsteady environments. Blade misalignment will affect the power capture of a tidal stream turbine and if not detected in time could affect other components of the drive train. Therefore, the aim of this paper is to compare the use of two numerical modelling techniques to predict the performance of a tidal stream turbine working under off-design conditions, in this case, the misalignment of one or more blades. The techniques used in this study are Blade Element Momentum Theory and Computational Fluid Dynamics. The numerical models simulate the performance of a three-bladed horizontal axis tidal stream turbine with one or two blades offset from the optimum pitch setting. The simulations were undertaken at 1.0 m/s flow speeds. The results demonstrated that both unsteady BEMT and steady or transient CFD are able to predict power coefficients when there is a certain level of misalignment in one or even two blades. However, both techniques failed to accurately predict a loss of power performance at high rotational speeds.]]></description>
      <pubDate>Mon, 29 Apr 2019 09:26:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1601540</guid>
    </item>
    <item>
      <title>Effects of inlet radial distortion on the type of stall precursor in low-speed axial compressor</title>
      <link>https://trid.trb.org/View/1492309</link>
      <description><![CDATA[Experimental investigations of the effect of inlet blade loading on the rotating stall inception process are carried out on a single-stage low-speed axial compressor. Temporal pressure signals from the six high response pressure transducers are used for the analysis. Pressure variations at the hub are especially recorded during the stall inception process. Inlet blade loading is altered by installing metallic meshed distortion screens at the rotor upstream. Three sets of experiments are performed for the comparison of results, i.e. uniform inlet flow, tip, and hub distortions, respectively. Regardless of the type of distortion introduced to the inflow, the compressor undergoes a performance drop, which is more severe in the hub distortion case. Under the uniform inlet flow condition, stall inception is caused by the modal type disturbance while the stall precursor switched to spike type due to the highly loaded blade tip. In the presence of high blade loading at the hub, spike disappeared and the compressor once again witnessed a modal type disturbance. Hub pressure fluctuations are observed throughout the process when the stall is caused by a modal wave while no disturbance is noticed at the hub in spike type stall inception. It is believed that the hub flow separation contributes to the modal type of stall inception phenomenon. Results are also supported by the recently developed signal processing techniques for the stall inception study.]]></description>
      <pubDate>Wed, 27 Dec 2017 10:29:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1492309</guid>
    </item>
    <item>
      <title>An Optical Fiber Measurement System for Blade Tip Clearance of Engine</title>
      <link>https://trid.trb.org/View/1458533</link>
      <description><![CDATA[The benefits of reducing the tip clearance have been receiving many scholars’ attention all the time, which bring turbine efficiency increasing, emissions reduction, payloads increasing, and mission range abilities extension. In order to gain the blade tip clearance dynamically, a prototype optical fiber measurement system was built and tested based on the rotor test rig. The optical fiber tip clearance measurement system consists of the reflective intensity-modulated optical fiber bundle (sensor), main signal processing unit, high-speed data acquisition card, and a computer. The static performance and dynamic performance experiments were conducted to verify the performance of the system the authors designed. In addition, the results show that the accuracy of the system is 25 μm or better; the stability of the measurement system was evaluated in room temperature. The clearance measurement range is about 5 mm, and sensitivity of the sensor is 0.0733/mm. Furthermore, the typical tip clearance dynamic measurement experiment results show that the system has good dynamic response characteristics as well. The system will provide a new tool for engine health monitoring or fast active tip clearance control.]]></description>
      <pubDate>Tue, 28 Mar 2017 17:08:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1458533</guid>
    </item>
    <item>
      <title>Experimental Investigation and Design of a Shape-variable Compressor Cascade</title>
      <link>https://trid.trb.org/View/1456262</link>
      <description><![CDATA[The design of jet engine compressor blading always implies a compromise between design and off-design operation. The reason for this is a fixed blade geometry which has to be operated over a wide range of operating conditions. Consequently, maximum achievable efficiencies at design operation are limited by off-design requirements, e.g., a certain stall margin. This paper describes an approach using shape-variable blades equipped with integrated piezoceramic-based macro fiber composite (MFC) Actuators on the blade’s suction and pressure sides. By applying a voltage to these actuators, it is possible to increase and to decrease the blade stagger angle and therefore the blade turning. Compared to a conventional fixed blade profile, the actuated design is thus adaptable within a certain range regarding ambient conditions. The first part of the paper describes the geometry and structure of the shape-variable blades for use in a compressor cascade experiment. In the next part, the three-dimensional deformation behavior of all manufactured blades at different shape conditions is characterized with a photogrammetric measurement system called ATOS. The first results without aerodynamic loads show an average displacement at the trailing edge of approximately Δz ≈ 0.9 mm compared to the non-actuated condition. This corresponds to an average outlet angle variation of approximately ∆κ2 ≈ ± 1°. The third part of the paper presents the results of the low speed cascade experiment using a fully actuated cascade. On the one hand, the objective is to determine the influence of blade actuation on aerodynamic characteristics such as flow outlet angle, total pressure loss and pressure distributions. On the other hand, optical blade displacement measurements are used to investigate combined two-dimensional (2D) and three-dimensional (3D) deformation effects of blade actuation in conjunction with aerodynamic loads. For these measurements, the ATOS system is also used. The wake evaluations show that maximum blade actuation leads to flow outlet angle deviations up to ± 1° which can be described by an almost linear shift of the cascade performance without changing the loss distribution significantly. Furthermore, for the chosen profile this margin is approximately constant over the operating range.]]></description>
      <pubDate>Mon, 27 Feb 2017 09:38:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1456262</guid>
    </item>
    <item>
      <title>Comparison of a Blade Element Momentum Model to 3D CFD Simulations for Small Scale Propellers</title>
      <link>https://trid.trb.org/View/1433398</link>
      <description><![CDATA[Many Small Unmanned Aerial Vehicles (SUAV) are driven by small scale, fixed blade propellers. Flow produced by the propeller can have a significant impact on the aerodynamics of a SUAV. Therefore, in Computational Fluid Dynamic (CFD) simulations, it is often necessary to simulate the SUAV and propeller coupled together. For computational efficiency, the propeller can be modeled in a steady-state view by using momentum source terms to add the thrust and swirl produced by the propeller to the flow field. Many momentum source term models are based on blade element theory. Blade element theory divides the blade into element sections in the spanwise direction and assumes each element to operate independently as a two-dimensional (2D) airfoil. Blade Element Momentum Theory (BEMT) for two small scale propellers are compared to high-fidelity, time-dependent 3D Reynolds Averaged Navier-Stokes (RANS) CFD simulations to determine the accuracy of approximating the complicated 3D flow associated with small scale propellers. Results show that BEMT acceptably predicts thrust when the propeller operates with little separation and the blade has a high aspect ratio with little or no chord variation. However, in large regions of separated flow and blades of lower aspect ratio and chord variation, the accuracy of BEMT diminishes. A secondary goal of this work is to create a basis for developing a more accurate steady-state surrogate model for the momentum imparted to the flow based on high-fidelity, time-dependent, 3D RANS CFD propeller blade simulations. An overview of this surrogate modeling process is briefly discussed.       ]]></description>
      <pubDate>Thu, 05 Jan 2017 16:24:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1433398</guid>
    </item>
    <item>
      <title>Blade Tip Clearance Sensors for Use in Engine Health Monitoring Applications</title>
      <link>https://trid.trb.org/View/1433356</link>
      <description><![CDATA[Blade tip clearance is a key design parameter for gas turbine designers. This parameter is often measured during engine testing and development phases as part of design validation but has yet to be utilized during normal engine fleet operation. Although blade tip clearance measurements are often mentioned for fleet operation in the context of active clearance control, the use of blade tip clearance measurements can provide an additional benefit for engine health monitoring. This paper explores the use of blade tip clearance sensors for engine condition monitoring of hot section blades. Blade tip clearance, especially in the first stage turbine, has an impact on exhaust gas temperature. The use of tip clearance measurements can provide supplementary information to traditional EGT measurements by providing a direct measurement of wear on the blade tips. In addition, blade creep and cracking can be measured and tracked if the sensors are able to provide clearance values of individual blades. Broken or missing blades can be identified allowing corrective action be taken in advance of normal inspection intervals. In order to enable health monitoring applications, blade tip clearance sensors must be survivable, repeatable, and provide high fidelity data. This paper discusses a microwave blade tip clearance sensor and discusses some of the key sensor attributes needed for successful health monitoring.]]></description>
      <pubDate>Thu, 05 Jan 2017 16:24:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1433356</guid>
    </item>
  </channel>
</rss>