Conventional Fin Research Articles

Evaluation of Coded Wire Tags for Marking Lake Trout

Abstract Among hatchery-reared lake trout (Salvelinus namaycush) of the 1979-1982 year classes stocked in New York waters of Lake Ontario, more than 3 million fish were marked with a coded wire tag (CWT) plus an adipose fin clip, and 1.5 million with only conventional fin clips. Altogether, 7,640 tags were recovered from fish collected with bottom trawls and gill nets or caught by anglers during 1980-1983. One person was able to extract and decipher 200 or more CWTs per day with about a 1% error rate in reading and recording codes. Presence of the CWT did not affect growth. The adipose fin clip did not regenerate. The occurrence of fish with an adipose fin clip but no CWT resulted primarily from the regeneration of paired fins among fish marked with a combination of the adipose fin and a paired fin. Loss of CWTs between marking and stocking (generally 4-5 months for fish stocked in spring and 1-8 d for fish stocked in fall) declined from nearly 11% for the 1979 year class stocked as fall fingerlings to le...

The effect of prandtl number on conjugate heat transfer from rectangular fins

The problem of conjugate heat transfer from rectangular fins is treated numerically. Results are provided for the three Prandtl numbers (three fluids) 0.021, 0.7 and 5.0 and convection - conduction parameters meters in the range of 0 ≤ √Re k fL/k sb = CCP ≤ 5. The results indicated great effects of both CCP and Pr. Comparisons with the simple conventional fin theory show that concerning the fin efficiency, the simple theory yields acceptable results while the temperature variation and local heat flux distributions are not correctly predicted.

Conjugate mixed convection and conduction heat transfer along a vertical circular pin

The heat transfer characteristics of laminar mixed convection flow over a vertical pin are studied analytically by conjugate convection-conduction theory. Numerical results for the local heat transfer coefficient, local heat flux, efficiency, and temperature distributions of pin under the effects of surface curvature, the buoyancy force parameter and the conjugate convection-conduction parameter, are obtained by solving simultaneously the convective boundary layer equations of the fluid and energy equations of the pin. The results of the present numerical solution have been compared with those of the conventional fin theory. It is found that there is some discrepancy between the pin efficiency and the temperature distribution.

Heat Transfer and Pressure Drop Performance of Finned Tube Bundles

The heat transfer and pressure drop performance of two types of finned tubes used in the air-conditioning industry are reported for 14 different bundle configurations. Twelve of these configurations contained a new type of finned tube called K-Y and two contained a more conventional pin fin. A unique characteristic of all these configurations is zero or negative fin-tip clearances. A comparison of the performance of these air-conditioning type finned tubes with negative fin-tip clearance is then made with the performance of typical air-cooled heat exchanger tubes used in the process and power industries. Both the heat transferred and the pressure drop are substantially higher with the air-conditioning configurations; the heat transfer coefficient is superior even to plain tubes. The very high heat transfer performance is more the result of the negative fin-tip clearance than the fin shape or type.

Conjugate mixed convection heat transfer from a vertical rectangular fin

A numerical investigation of the heat transfer from a rectangular fin by combined forced and natural convection is presented. Results are given for buoyancy parameters in the range of 0 ⩽ Gr/Re 2 ⩽ 2 and convection - conduction parameters in the range of 0 ⩽ √ Re k fL/k sb ⩽ 10 . The results are compared with the conventional fin theory and it is found that concerning the fin efficiency, the latter produces acceptable results although it is not strictly correct.

A Natural Convection Fin with a Solution-Determined Nonmonotonically Varying Heat Transfer Coefficient

A conjugate conduction-convection analysis has been made for a vertical plate fin which exchanges heat with its fluid environment by natural convection. The analysis is based on a first-principles approach whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum, and energy in the fluid boundary layer adjacent to the fin. The natural convection heat transfer coefficient is not specified in advance but is one of the results of the numerical solutions. For a wide range of operating conditions, the local heat transfer coefficients were found not to decrease monotonically in the flow direction, as is usual. Rather, the coefficient decreased at first, attained a minimum, and then increased with increasing downstream distance. This behavior was attributed to an enhanced buoyancy resulting from an increase in the wall-to-fluid temperature difference along the streamwise direction. To supplement the first-principles analysis, results were also obtained from a simple adaptation of the conventional fin model.

An Efficient Algorithm for Evaluating Arrays of Extended Surface

In the consideration of single longitudinal fins of rectangular, trapezoidal, and triangular profile and in arrays of extended surface composed of these fins, it is shown that conditions of heat flow and temperature excess at the fin or array tip induce conditions of heat flow and temperature excess at the fin or array base. In particular, there is a linear transformation between the aforementioned data at the fin tip and the fin base. The conventional fin efficiency is abandoned and single fins or arrays of extended surface are instead characterized by a single important parameter, the heat flow to temperature excess ratio, which is a function only of fin geometry and heat transfer parameters. Algorithms are provided for combining the effects of individual fins in arrays of extended surface. A modification of the procedures developed leads to an exact solution for the double stack with unequal heat distribution at opposite ends, a problem which has heretofore required iterative solution procedures.

Comparative Efficiencies of Conventional and Super-Swimfin Designs

One female and six male subjects were used to evaluate the effectiveness of four modern “super-swimfin” designs when compared to a set of conventional fins. Oxygen consumption and heart rates were measured at a predetermined submaximal workload using a swimming ergometer. Times for kicking 22.9 m were also compared. The results demonstrated that significantly less oxygen was consumed during the trials in which the vented super-fins of large surface area were used than when the conventional fins were used. Significant V̇O2differences were also noted between super-fins, with large surface area, inflexible, or venturi designs resulting in the consumption of more oxygen than the others. A statistically significant linear correlation (r = −.90) was computed when comparing oxygen consumption to fin surface area. Flexibility of the fins was noted to be directly related to the speed that could be attained (r = .90). It was concluded that only the super-fin designs that were vented and had a large surface area are more efficient than the conventional fins tested.

Preliminary Control System Using Preferred Feedback States

Theme T objectives of this paper are twofold: first, to present the fin position 6 and body rate 0 feedback shaping transfer functions that equate a conventional fin feedback autopilot to a autopilot that replaces fin feedback with body angular acceleration 6 as a feedback signal. The word reference is used because there are no practical angular accelerometer sensors available for measuring body angular accelerations, and also, for analysis reasons, the angular acceleration loop is assumed to be free of the tolerance problem that is inherent in matching M6 in the feedback path with M5 in the forward path. The second objective is to demonstrate the practical application of this control scheme by analysis and examples with the end view being to facilitate rigid-body autopilot design work and to maximize the controllable aerodynamic regime of vehicles that are subject to large Ma.

Performance efficiency of swim fins

Design improvements on swim fins are most difficult, if not impossible, to assess quantitatively by swimmers alone. In order to make reliable measurements of swim fin performance, an instrumented mechanical swimming device was developed and operated in a water tank. Using this facility, the performance of the more popular conventional fins and that of a new design concept were evaluated. The comparative performance of the various fins was correlated with their physical characteristics.

Periodic Heat Transfer in Straight Fins

The characteristics of heat transfer in straight fins with periodic variation of base temperature have been determined analytically. The heat-transfer process is governed by three dimensionless parameters: the conventional fin parameter N, the frequency parameter B, and the amplitude parameter A. The effects of these parameters on the instantaneous and average heat flow rates, axial and time-wise temperature distributions, and instantaneous and average fin efficiencies are demonstrated by several examples. In general, the time-average fin efficiency is reduced by the periodic variation of the base temperature.

Mass minimization of radiating trapezoidal fins with negligible base cylinder interaction

An optimization procedure is presented for achieving maximum dissipation from a longitudinal fin system of trapezoidal profile with mutual irradiation. The fins are conceived to be arranged symmetrically around a small base cylinder of uniform temperature. The governing equation for the temperature field along the fin is formulated in terms of finite summation and differences. The resulting set of simultaneous, non-linear, algebraic equations was solved by iteration using the Newton-Raphson method. A new dimensionless parameter is proposed to characterize the total dissipating capacity of a fin system with mutual irradiation. Its use has advantage over the conventional fin effectiveness in design application. Trapezoidal fins, including triangular and rectangular profiles, were investigated for a wide range of emissivities and incident space radiation. Optimum fin number and their proportions were determined and charts of dissipation capacity were presented. This analysis also leads to an expression suitable for comparing performance of fin systems fabricated of materials of different conductivity and density. For a fixed total mass of the fin material, the maximum dissipation varies as the 1 3 power of the quantity k ρ , other factors remain unaltered.

Gas-Si Wall Temperatures in Rib-Backed Liquid-Cooled Combustion Chambers

I IS of considerable value to obtain estimates of the temperatures of spots that may occur on the wall surfaces of rocket combustion chambers. One form of hot spot can occur when a thin wall is reinforced by a thick rib or spacer to satisfy structural requirements. Adding a rib or is normally desirable from a heat transfer viewpoint since the effective coolant-side surface area is generally increased. However, conditions do exist where a liquid coolant film resistance is very small in comparison with the resistance of the wall material. The rib, if wide enough, can therefore effectively impede the local heat flux to the liquid and raise the gas-side wall temperature several hundred degrees above the temperature of the wall surfaces remote from the rib. The exact dividing line between a cooling fin and an insulating fin is rather difficult to establish analytically. If we accept conventional fin efficiency equations as valid, the heat flow from a rectangular plane fin is given by