Numerical Simulation for Comparative Thermo-Hydraulic Performance of Turbulent Flow in Tubes with Twisted Tape Inserts

This article focused on investigating numerically the effects of key design parameters including tape thickness, tube wall to tape edge clearance and three different perforated shapes cut (circular, triangular and pentagon) on the heat transfer coefficient enhancement in tube with twisted tape inserts. Water was considered as the working fluid under the turbulent flow of Reynolds number (Re) between 12,000 and 22,000, with constant wall temperature of the tubes. It is found that due to the swirling flow and efficient mixing of the fluid, all the tape inserts considered in this study produced better thermalhydraulic performance than the plain tube without an insert. At the same time, tape inserts with small tube wall to tape edge clearance and considerable thickness value is beneficial to reduce the friction factor, consequently enhancing the heat transfer rate. Through the thermal performance factor (TPF) evaluation, the twisted tape with perforated triangular shape cut has an advantage over the pentagon and circular shapes cut with increasing Re. A maximum TPF as high as 1.68 can be obtained for the twisted tape with perforated triangular shape cut under low turbulent Re.

Aerodynamics of leading-edge protection tapes for wind turbine blades

This paper presents results of a comparative study on the effect of standard and tapered leading-edge protection (LEP) tapes on the annual energy production (AEP) of a utility-scale 1.5 MW wind turbine. Numerical models are developed in STAR-CCM+ to estimate the impact of LEP tapes on lift and drag coefficients of an NACA 64-618 airfoil operating at Re = 3 × 106. Experimental drag coefficient data are collected for LEP tapes applied to the tip-section of a de-commissioned wind turbine blade for numerical validation. The objective is to determine the physical mechanisms responsible for the aerodynamic degradation observed with standard LEP tapes, and to design a tapered LEP tape that reduces the associated adverse impact on AEP. An in-house wind turbine design and analysis code, XTurb-PSU, is used to estimate AEP using airfoil data obtained by STAR-CCM+. For standard LEP tapes, laminar-to-turbulent boundary-layer transition occurs at the LEP tape edge, resulting in AEP losses of 2%–3%. Comparable tapered LEP tapes can be designed to suppress boundary-layer transition for backward-facing step heights below a critical value such that associated impact on AEP is negligible.

The Detection and Control of Tape Deviation in Winding Process

In the winding process, the tape always has a lateral shift along the mandrel due to various reasons. Thus, a straight-line running cannot be maintained. If effective measures are not taken in time, the tape deviation will result in the phenomenon of corrugation and crinkling. Additionally, it would influence negatively on the precise control of tension and the quality of wound products. The tape-edge detection method, based on the charge coupled device (abbreviated as CCD) linear image sensor, is proposed to detect the deviation amount. With regard to the characteristics of PID controller and Fuzzy controller, the combined controller of Fuzzy-PID is raised. According to simulations and experiments, the effect of Fuzzy-PID controller is obviously better than that of PID controller or Fuzzy controller. By presenting the detection and control techniques for the tape deviation, the automatic rectification is achieved, the consecution and the automation degree of winding process is improved as well. Therefore, the quality of wound products is guaranteed.

Measurement and Sources of Lateral Tape Motion: A Review

The sources of lateral tape motion in a tape drive are reviewed. Currently used measurement methods and models for lateral tape motion are analyzed and compared. The effect of roller run-out, tape edge contact, and tape tension transients on lateral tape motion is discussed. A dual stage actuator tape head is investigated to improve track-following capability and increase the track density on a magnetic tape.

Characterization of Tape Edge Contact Force With Acoustic Emission

Acoustic emission sensors were used to detect contact between a moving tape and the flange of a tape guide. The influence of tape drive operating conditions on the tape edge contact force was studied. A one-dimensional model was developed to predict the magnitude of tape/flange impact. The model fits the experimental data well.