Measurements of heat transfer coefficients for jet impingement array using thermo chromic liquid crystal (TLC)‎ technique

Dissertant

al-Qaysi, Khalid A. S.

University

University of Technology

Faculty

-

Department

Department of Electromechanical Engineering

University Country

Iraq

Degree

Master

Degree Date

2009

English Abstract

Spatial heat transfer coefficients distribution measurements have been made using thermochromie liquid crystal technique for several cases of normally impinging air jet arrays onto a flat, smooth surface within a three sides closed channel.

The study investigated the effect of the number of jets, and jet-to-target plate spacing (Z/D), for the target plate in the presence of a cross flow originating from upstream jets on the heat transfer distribution of jets' target plate.

Two-dimensional inline anays of circular jets of air impinging on a heat transfer surface parallel to the jet-issuing plate were considered.

The air, after impingement, was constrained to exit in a single direction along a channel formed by the target plate, the jet-issuing plate and the spacers, The downstream jets were subjected to a cross flow from the upstream jets.

Jet distribution was tested according to 3 sets : 3 rows with 3 holes in each row, 5 rows with 5 holes in each row, and 7 rows with 7 holes in each row.

The jet-to-jet spacing X/D for all jet plates was 2, 3, and 4 holes in diameter in the span wise direction and the same in the stream wise direction.

Tests were conducted at a Reynolds number between 121 and 751.

The heat transfer measurement used a liquid crystal imaging technique with a one-dimensional transient conduction model.

The impingement heat transfer results are correlated in terms of the non-dimensional parameters ; Reynolds number (Re), X at constant jet whole diameter (X / D) and gap height at constant jet diameter (Z / D), the following correlation was obtained.

The measurement system was verified by comparing against well-known data sets of heat transfer measurement, Kerchief and Tabak off (1970) [S4], for a simplified model, a 49~hole target plate (X / D = 2), the discrepancy from the current measurement system has been found to be no more than 5%.

An optimum distance for jet-to-target plate spacing was found to be Z / D = 0.5 for the 9-hole case (X / D = 4), the 25-hole case (X / D = 3) is Z/D=3t and for the 49-hule case (X/ D = 2) is Z / D = 3.

Main Subjects

Mechanical Engineering

Topics

• Thermodynamics
• Jet aircraft

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-304957