Cengiz Camci | The Pennsylvania State University (original) (raw)

Papers by Cengiz Camci

This paper deals with the implementation of Pressure Sensitive Paints (PSP) in turbomachinery and... more This paper deals with the implementation of Pressure Sensitive Paints (PSP) in turbomachinery and other aero-thermal research studies. A specific calibration setup developed at the Pennsylvania State University and the applications of PSP are discussed in detail. PSP is an experimental technique for mapping pressure distributions on any aerodynamic body. It requires coating the surface of the body with a special paint that exhibits luminescence when it is exposed to light of appropriate frequency. The intensity of the exposed light is then used as a measure of the pressure at that point. In order to draw up a reference criteria, calibration of the paint was carried out in a specially designed chamber. The paper provides details about the calibration procedure as well as the setup. Although in the recent years PSP has been used for the investigation of high speed flows, its low-speed applications are also being investigated. The current effort aims at using PSP technology in explorin...

This paper deals with the description of the Axial Flow Turbine Research Facility (AFTRF) install... more This paper deals with the description of the Axial Flow Turbine Research Facility (AFTRF) installed at the Turbomachinery Laboratory of the Pennsylvania State University. The AFTRF is a single-stage cold flow turbine specifically designed for studying unsteady/turbulent viscous flow details of three-dimensional passage flows. The facility diameter is 91.66 cm (3 feet) and the hub-to-tip ratio of the blading is 0.73. 23 nozzle vanes and 29 rotor blades followed by outlet guide vanes. The blading design embodies modem HP turbine design philosophy, loading and flow coefficient, reaction, aspect ratio, and blade turning angles, all within current aircraft engine design turbine practice. State-of-the-art quasi-3D blade design techniques were used to design the vane and the blade shapes. The vanes and blades are heavily instrumented with fast response pressure, shear stress, and velocity probes and have provision for flow visualization and laser Doppler anemometer measurement. Furthermore...

The relative aerodynamic and performance effects associated with rotor ‐NGV gap coolant injection... more The relative aerodynamic and performance effects associated with rotor ‐NGV gap coolant injections were investigated in the Axial Flow Turbine Research Facility (AFTRF) of the Pennsylvania State University. This study quantifies the effects of the coolant injection on the aerodynamic performance of the turbine for radial cooling, impingement cooling in the wheelspace cavity and root injection. Overall, it was found that even a small quantity (1 percent) of cooling air can have significant effects on the performance character and exit conditions of the high pressure stage. Parameters such as the total-to-total efficiency, total pressure loss coefficient, and three-dimensional velocity field show local changes in excess of 5, 2, and 15 percent, respectively. It is clear that the cooling air disturbs the inlet end-wall boundary layer to the rotor and modifies secondary flow development, thereby resulting in large changes in turbine exit conditions. @DOI: 10.1115/1.1401026#

This paper briefly describes a novel ducted fan inlet flow-conditioning concept that will signifi... more This paper briefly describes a novel ducted fan inlet flow-conditioning concept that will significantly improve the performance and controllability of ducted fans operating at high angle of attack. High angle of attack operation of ducted fans is very common in VTOL (vertical take-off and landing) UAV systems. The new concept that will significantly reduce the inlet lip separation related performance penalties in the edgewise/forward flight zone is named DOUBLE-DUCTED FAN (DDF). The current concept uses a secondary stationary duct system to control inlet lip separation related momentum deficit at the inlet of the fan rotor occurring at elevated edgewise flight velocities. The DDF is self-adjusting in a wide edgewise flight velocity range and its corrective aerodynamic effect becomes more pronounced with increasing flight velocity due to its inherent design properties. In this manuscript, after a comprehensive discussion of VTOL inlet flow distortion issues, a conventional baseline d...

This technical paper describes a novel ducted fan inlet flow conditioning concept that will signi... more This technical paper describes a novel ducted fan inlet flow conditioning concept that will significantly improve the performance and controllability of V/STOL ‘vertical/short take off take-off and landing” UAVs ‘uninhabited aerial vehicles” and many other ducted fan based systems. The new concept that will significantly reduce the inlet lip separation related performance penalties in the forward flight zone is named ‘DOUBLE DUCTED FAN (DDF)”. The current concept uses a secondary stationary duct system to control ‘inlet lip separation” related momentum deficit at the inlet of the fan rotor occurring at elevated forward flight velocities. The DDF is self-adjusting in a wide forward flight velocity range. DDFs corrective aerodynamic influence becomes more pronounced with increasing flight velocity due to its inherent design properties. The DDF can also be implemented as a ‘Variable Double Ducted Fan” (VDDF) for a much more effective inlet lip separation control in a wide range of hori...

The International Journal of Rotating Machinery, 2002

Journal of Turbomachinery, 2000

Investigation of the internal fluid mechanic losses for a turbine blade with trailing edge coolan... more Investigation of the internal fluid mechanic losses for a turbine blade with trailing edge coolant ejection was present in Uzol et al. (2001). The current study is a detailed experimental investigation of the external subsonic flowfield near the trailing edge and the investigation of the external aerodynamic loss characteristics of the turbine blade with trailing edge coolant ejection system. Particle Image Velocimetry experiments and total pressure surveys in the near wake of the blade are conducted for two different Reynolds numbers and four different ejection rates. Two different trailing edge configurations with different cut-back lengths are also investigated. Numerical simulations of the flowfield are also performed for qualitative flow visualization purposes. Two-dimensional, incompressible, and steady solutions of Reynolds-averaged Navier–Stokes equations are obtained. A two-equation standard k-ε turbulence model coupled with an Algebraic Reynolds Stress Model is used for th...

Journal of Heat Transfer, 2005

This paper presents the results of heat transfer, total pressure loss, and wake flow field measur... more This paper presents the results of heat transfer, total pressure loss, and wake flow field measurements downstream of two-row staggered elliptical and circular pin fin arrays. Two different types of elliptical fins are tested, i.e., a Standard Elliptical Fin (SEF) and a fin that is based on NACA four digit symmetrical airfoil shapes (N fin). The results are compared to those of a corresponding circular pin fin array. The minor axis lengths for both types of elliptical fins are kept equal to the diameter of the circular fins. Experiments are performed using Liquid Crystal Thermography and total pressure probe wake surveys in a Reynolds number range of 18 000 and 86 000 as well as Particle Image Velocimetry (PIV) measurements at ReD=18 000. The pin fins had a height-to-diameter ratio of 1.5. The streamwise and the transverse spacings were equal to one circular fin diameter, i.e., S/D=X/D=2. For the circular fin array, average Nusselt numbers on the endwall within the wake are about 27...

Journal of Heat Transfer, 1997

Liquid crystal thermography is an effective method widely employed in transient and steady-state ... more Liquid crystal thermography is an effective method widely employed in transient and steady-state heat transfer experiments with excellent spatial resolution and good accuracy. Most of the past studies in liquid crystal thermography deal with stationary conditions. The present investigation deals with the influence of rotation on the color response of encapsulated liquid crystals attached to a flat rotating surface. A general methodology developed for the application of thermochromic liquid crystals in rotating systems is described for the first time. The investigation is performed for a rotational speed range from 0 to 7500 rpm using two different coatings displaying red at 30° and 45°C, under stationary conditions. Local liquid crystal color on the surface of a rotating disk is correlated with local temperature as measured by a non-intrusive infrared sensor at various rotational speeds. An immediate observation from the present study is that the color response (hue) of encapsulated...

Journal of Heat Transfer, 1993

Accurate determination of convective heat transfer coefficients on complex curved surfaces is ess... more Accurate determination of convective heat transfer coefficients on complex curved surfaces is essential in the aerothermal design and analysis of propulsion system components. The heat transfer surfaces are geometrically very complex in most of the propulsion applications. This study focuses on the evaluation of a hue capturing technique for the heat transfer interpretation of liquid crystal images from a complex curved heat transfer surface. Impulsively starting heat transfer experiments in a square to rectangular transition duct are reported. The present technique is different from existing steady-state hue capturing studies. A real-time hue conversion process on a complex curved surface is adopted for a transient heat transfer technique with high spatial resolution. The study also focuses on the use of encapsulated liquid crystals with narrow color band in contrast to previous steady-state hue based techniques using wide band liquid crystals. Using a narrow band crystal improves ...

personal.psu.edu

An experimental study of a turbine tip desensitization method based on tip coolant injection was ... more An experimental study of a turbine tip desensitization method based on tip coolant injection was conducted in a large-scale rotating turbine rig. One of twenty-nine rotor blades was modified and instrumented to have a tip trench with discrete injection holes directed ...

flows Rotational frame velocity and pressure measurements were made downstream of a rotor blade r... more flows Rotational frame velocity and pressure measurements were made downstream of a rotor blade row in a single stage turbine research rig. Measurements were taken at two axial locations to track the development of the secondary flow in the blade tip region using a five hole probe. Coolant mass flow was injected at several locations on the rotor tip to investigate the effect of coolant air on the secondary flow. The ultimate objective is to re-duce losses by the introduction of high momentum air in the tip gap. Results indicate that the passage and the leakage vortices re-tain their structures up to at least 46 % chord-length downstream of the rotor trailing edge. The cooling air, which is 0.3 % of the total mass-flow, appears to be well mixed with the leakage flow and makes little difference to the flow field downstream of the ro-tor. It appears that a relatively large amount of cooling air ought to be injected from specific locations on the rotor tip to cause any significant chang...

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery, 2001

Aerodynamic losses due to the formation of a leakage vortex near the tip section of rotor blades ... more Aerodynamic losses due to the formation of a leakage vortex near the tip section of rotor blades form a significant part of viscous losses in axial flow turbines. The leakage flow, mainly induced by the pressure differential between the pressure side and suction side of a rotor tip section, usually rolls into a streamwise vortical structure near the suction side part of the blade tip. The current study uses the concept of a tip platform extension that is a very short “winglet” obtained by slightly extending the tip platform in the tangential direction. The use of a pressure side tip extension can significantly affect the local aerodynamic field by weakening the leakage vortex structure. Phase averaged, time accurate total pressure measurements downstream of a single stage turbine facility are provided from a total pressure probe that has a time response of 150 kHz. Complete total pressure maps in all of the 29 rotor exit planes are measured accurately. Various pressure and suction s...

Progress in Computational Fluid Dynamics, An International Journal, 2007

Journal of Turbomachinery, 2005

This paper deals with an experimental investigation of aerodynamic characteristics of full and pa... more This paper deals with an experimental investigation of aerodynamic characteristics of full and partial-length squealer rims in a turbine stage. Full and partial-length squealer rims are investigated separately on the pressure side and on the suction side in the “Axial Flow Turbine Research Facility” (AFTRF) of the Pennsylvania State University. The streamwise length of these “partial squealer tips” and their chordwise position are varied to find an optimal aerodynamic tip configuration. The optimal configuration in this cold turbine study is defined as the one that is minimizing the stage exit total pressure defect in the tip vortex dominated zone. A new “channel arrangement” diverting some of the leakage flow into the trailing edge zone is also studied. Current results indicate that the use of “partial squealer rims” in axial flow turbines can positively affect the local aerodynamic field by weakening the tip leakage vortex. Results also show that the suction side partial squealers...

High-speed ground tracking radars rotating at about 60 rpm are being implemented as modern air tr... more High-speed ground tracking radars rotating at about 60 rpm are being implemented as modern air traffic control systems in airports. The flow induced vibration and noise generation of the newly developed radar antennas are the two serious problems that jeopardize the successful deployment of the new ground aircraft tracking systems. This paper deals with the viscous flow details of the highly three-dimensional antenna tip section and the vortex shedding characteristics at Re=426,000. The current analysis uses a 3D computational approach for the computation of viscous flow details with the highly 3 D tip geometry. A 2D unsteady computation of the vortex shedding phenomena is also presented. This paper is a continuation of the computational study dealing with the determination of aerodynamic drag coefficients on ASDE-X (Advanced Surface Detection Equipment) antenna cross sections previously presented in Gumusel et al. (1).

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration, 1997

Impinging jets are widely used in local enhancement of heat removed from internal passages of gas... more Impinging jets are widely used in local enhancement of heat removed from internal passages of gas turbine blades. Arrays of stationary jets are usually impinged on inner surfaces of gas turbine blades exposed to severe thermal/hydrodynamic environment of hot mainstream gases. The current practice is to benefit from the high heat transfer coefficients existing in the immediate vicinity of the jet impingement region on a target wall. The present study shows that a self-oscillating impinging-jet configuration can be extremely beneficial in enhancing the heat removal performance of a conventional stationary impinging jet. In addition to a highly elevated stagnation line Nusselt number, the area coverage of the impingement zone is significantly enlarged because of the sweeping motion of the oscillating coolant jet. When an oscillating jet (Re = 14,000) is impinged on a plate normal to the jet axis (x/d = 24 hole to plate distance), a typical enhancement of Nu number on the stagnation lin...

Journal of Heat Transfer, 2002

Impinging jets are widely used in the local enhancement of heat removed from internal passages of... more Impinging jets are widely used in the local enhancement of heat removed from internal passages of gas turbine blades. Arrays of stationary jets are usually impinged on surfaces of internal cooling passages. The current practice is to benefit from the high heat transfer coefficients existing in the vicinity of the jet impingement region on a target wall. The present study shows that a self-oscillating impinging-jet configuration is extremely beneficial in enhancing the heat removal performance of a conventional (stationary) impinging jet. In addition to a highly elevated stagnation line Nusselt number, the area coverage of the impingement zone is significantly enhanced because of the inherent sweeping motion of the oscillating coolant jet. When an oscillating jet (Re=14,000) is impinged on a plate normal to the jet axis (x/d=24 hole to plate distance), a typical enhancement of Nu number on the stagnation line is about 70 percent. The present paper explains detailed fluid dynamics str...

Flow within the space between the rotor and stator of a turbine disk, an area referred to as the ... more Flow within the space between the rotor and stator of a turbine disk, an area referred to as the rim seal cavity, develops azimuthal velocity component from the rotor disk. The fluid within develops unsteady structures that move at a faction of the rotor speed. A test is developed to measure the number of unsteady structures and the rotational speed at which they are moving in the rim seal cavity of an experimental research rig. Data manipulation was developed to extract the speed and the numbers of structures present using two fast response aerodynamic probes measuring static pressure on the surface of the stator side rim seal cavity. A computational study is done to compare measured results to a transient URANS. The computational simulation consists of 8 vanes and 10 blades, carefully picked to reduce error caused by blade vane pitch mismatch and to allow for the structures to develop correctly, and the rim seal cavity to measure the speed and number of the structures. The experim...