Analysis of heat transfer enhancement in microchannel by varying the height of pin fins at upstream and downstream region

In this study, a numerical analysis of a microchannel with the different configuration of varying height of pin fins entrenched at the bottom of the channel base wall has been carried out. Five different configurations of pin fins arrangement which are considered in this study are, Case 1(Full length fins in complete microchannel), Case 2(Full length fins at the upstream), Case 3(Full length fins at the downstream), Case 4(Full length fin at the center of microchannel), Case 5(Full length fins at the inlet and exit of microchannel) and the results of these five cases are compared with the plain rectangular microchannel. In this investigation, deionized ultra-filtered water is used and Reynold’s number is ranging from 150 to 350. Results reveals that the highest Nusselt number is achieved by case 2 at a lesser value of Reynold’s number while by case 5 at higher Reynold’s number and the lowest pressure drop is occurring in case 4. The overall thermal performance of case 2 beats the corresponding cases.

Estimation of Minor Loss Coefficient Associated with Fitting of Venturimeter in a Pipe System

Quantification of minor losses associated with a pipe fitting and regular updating is necessary for ensuring the sustainability of the system. In this study, based on simple lab based experiments, the minor loss coefficient associated with a venturimeter fitted in a pipe system is estimated. It is seen that the loss coefficient varies inversely with the increase in the Reynold’s number and can be depicted with a simple mathematical equation.

A Variable Camber Piezocomposite Trailing-Edge for Subsonic Aircraft: Multidisciplinary Design Optimization

A continuous-surface morphing airfoil is desirable for commercial aircraft in order to improve fuel efficiency, and due to the potential to morph the wing into a high-lift configuration for take-off and landing. Piezocomposite actuators have shown to be a feasible strategy for camber morphing in small unmanned fixed-wing aircraft with a Reynold’s number in the range of 50,000 to 250,000. As an extension, this paper presents a theoretical framework and results for morphing in single and multi-segment natural laminar flow airfoils with a maximum Reynold’s number of 825,000. The airfoils presented employ a continuous inextensible surface. To achieve morphing, piezocomposite actuating elements are applied on the suction and pressure surfaces of the airfoils. The geometric properties of the airfoils are determined using a genetic algorithm optimization method with a migration strategy in order to maintain population diversity. The algorithm optimizes independently the substrate thicknesses for the nominal airfoil, the leading edge, and the piezocomposite bonded surfaces. In addition, positions and voltages for each piezocomposite actuators are optimized. The genetic algorithm uses an objective function to maximize the change in coefficient of lift to morph the airfoil from its baseline (i.e. cruise) state to the high-lift state. Analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. Optimization is followed by a parametric analysis to examine lift, drag, and lift-to-drag ratio of the airfoils over their full operational range. The optimization is performed on a symmetric, asymmetric, and the aft element of a slotted multi-segment airfoil to examine the capabilities of induced-strain actuation at high dynamic pressures.

A Piezocomposite Trailing-Edge for Subsonic Aircraft

This paper examines the feasibility of piezocomposite morphing airfoils and trailing edge control surfaces subjected to large dynamic pressures. Piezocomposite airfoils have been shown to be feasible on small unmanned aerial vehicles, subject to relatively low dynamic pressures, operating in the Reynold’s number range of 50k to 250k. The operating range of interest in this paper has a cruising Reynold’s number range between 250k and 1M subject to relatively large wing loading. This range of Reynold’s numbers has not been explored in detail due to the large aerodynamic loads produced. Based on the authors’ previous research on small unmanned aircraft, the proposed concept is a variable-camber airfoil that employs a continuous inextensible surface and surface-bonded piezocomposite actuators. To achieve camber-morphing, multiple piezocomposite actuating elements are applied to the upper and lower surfaces. A case study is performed to determine the design parameters of the airfoil. The parameters to be varied include the substrate thickness of the baseline airfoil, leading edge, and piezocomposite bonded areas. In addition, the positions of the piezocomposites are varied. The analysis is performed using a coupled fluid-structure interaction model assuming static aeroelastic behavior. A voltage sweep is conducted on each airfoil design while being subjected to 70 m/s free stream velocity. The sweep examines the lift coefficient and lift-to-drag ratio of the airfoil over the full operational range. This research lays the groundwork for determining the feasibility of piezocomposite morphing airfoil and trailing edge concepts for use in applications subject to large dynamic pressures.