Model representation in the PANCOR wall interference assessment code

An investigation into the aircraft model description requirements of a wall interference assessment and correction code known as PANCOR was conducted. The accuracy necessary in specifying various elements of the model description were defined. It was found that the specified lift coefficient is the most important model parameter in the wind tunnel simulation. An accurate specification of the model volume was also found to be important. Also developed was a partially automated technique for generating wing lift distributions that are required as input to PANCOR. An existing three dimensional transonic small disturbance code was modified to provide the necessary information. A group of auxiliary computer programs and procedures was developed to help generate the required input for PANCOR

Probabilistic Flow Regime Map Modeling of Two-Phase Flow

The purpose of this investigation is to develop models for two-phase heat transfer, void fraction, and pressure drop, three key design parameters, in single, smooth, horizontal tubes using a common probabilistic two-phase flow regime basis. Probabilistic two-phase flow maps are experimentally developed for R134a at 25 ??C, 35 ??C, and 50 ??C, R410A at 25 ??C, mass fluxes from 100 to 600 kg/m2-s, qualities from 0 to 1 in 8.00 mm, 5.43 mm, 3.90 mm, and 1.74 mm I.D. horizontal, smooth, adiabatic tubes in order to extend probabilistic two-phase flow map modeling to single tubes. An automated flow visualization technique, utilizing image recognition software and a new optical method, is developed to classify the flow regimes present in approximately one million captured images. The probabilistic two-phase flow maps developed are represented as continuous functions and generalized based on physical parameters. Condensation heat transfer, void fraction, and pressure drop models are developed for single tubes utilizing the generalized flow regime map developed. The condensation heat transfer model is compared to experimentally obtained condensation data of R134a at 25 ??C in 8.915 mm diameter smooth copper tube with mass fluxes ranging from 100 to 300 kg/m2-s and a full quality range. The condensation heat transfer, void fraction, and pressure drop models developed are also compared to data found in the literature for a wide range of tube sizes, refrigerants, and flow conditions.Air Conditioning and Refrigeration Project 18

Investigation of Adiabatic Refrigerant Pressure Drop and Flow Visualization in Flat Plate Evaporators

Adiabatic pressure drop and flow visualization in chevron plate, 1:1 aspect ratio bumpy plate, and 2:1 aspect ratio bumpy plate heat exchangers were investigated for vertical upward flow with R134a. Qualities ranging from subcooled liquid to superheated vapor were investigated. Mass fluxes ranged from 16 kg/m2-s (for superheated vapor) to approximately 300 kg/m2-s (for sub-cooled liquid). The pressure drop experiments were conducted for 10o C and 20o C inlet temperatures. The flow visualization experiments were conducted at a 10o C inlet temperature. The following is the order of highest to lowest pressure drop geometries on both a mass flux and mass flow bases: chevron plate, 1:1 aspect ratio bumpy plate, and 2:1 aspect ratio bumpy plate. These trends are more pronounced on a mass flow basis. Four flow regimes were observed for the flat plate geometries investigated and are mapped out on a mass flux versus quality basis for each geometry. The chevron geometry was seen to undergo flow transitions at lower qualities and mass fluxes than the bumpy plate geometries. The kinetic energy per unit volume of the flow was found to have a strong linear relationship with pressure drop for both single-phase and two-phase flow, suggesting that inertial effects are the dominant mode of pressure drop in flat plate heat exchangers. Vapor pressure drop prediction models based on the kinetic energy of the flow are presented, which predict pressure drop within 20%. A two-phase pressure drop model is developed, also based on kinetic energy per unit volume of the flow. A pseudo void fraction is defined in order to correlate the two-phase pressure drop to the single-phase pressure drop. The two-phase pressure drop model predicts two-phase pressure drop to within 15% of experimental measurements. A description of and modifications to the experimental test facilities are provided. In addition, the geometries and construction of the plates are provided.Air Conditioning and Refrigeration Project 12