Engine component improvement: JT8D and JT9D performance improvements

A feasibility analysis screening method for predicting the airline acceptance of a proposed engine performance improvement modification was developed. Technical information derived from available test data and analytical models is used along with conceptual/preliminary designs to establish the predicted performance improvement, weight and installation characteristics, the cost for new production and retrofit, maintenance cost and qualitative characteristics of the performance improvement concepts being evaluated. These results are used to arrive at the payback period, which is the time required for an airline to recover the investment cost of concept implementation, and to predict the amount of fuel saved by a performance improvement concept. The assumptions used to calculate the payback period and fuel saved are discussed. A summary of the results when the screening method is applied is presented for several representative JT8D and JT9D performance improvement concepts. An example of the input information used to develop the summary results is shown

JT8D high pressure compressor performance improvement

An improved performance high pressure compressor with potential application to all models of the JT8D engine was designed. The concept consisted of a trenched abradable rubstrip which mates with the blade tips for each of the even rotor stages. This feature allows tip clearances to be set so blade tips run at or near the optimum radius relative to the flowpath wall, without the danger of damaging the blades during transients and maneuvers. The improved compressor demonstrated thrust specific fuel consumption and exhaust gas temperature improvements of 1.0 percent and at least 10 C over the takeoff and climb power range at sea level static conditions, compared to a bill-of-material high pressure compressor. Surge margin also improved 4 percentage points over the high power operating range. A thrust specific fuel consumption improvement of 0.7 percent at typical cruise conditions was calculated based on the sea level test results

The JT8D and JT9D engine component improvement: Performance improvement program

The NASA sponsored Engine Component Improvement - Performance Improvement Program at Pratt & Whitney Aircraft advanced the state of the art of thermal barrier coatings and ceramic seal systems, demonstrated the practicality of an advanced turbine clearance control system and an advanced fan design in the JT9D engine, and demonstrated the advantages of modern cooling, sealing, and aerodynamic designs in the high pressure turbine and compressor of the JT8D engine. Several of these improvements are already in airline service in JT8D and JT9D engines, and others will enter service soon in advanced models of these engines. In addition, the technology advances are being transferred to completely new engine configurations, the PW2037 engine and the NASA sponsored Energy Efficient Engine

JT8D and JT9D jet engine performance improvement program. Task 1: Feasibility analysis

JT8D and JT9D component performance improvement concepts which have a high probability of incorporation into production engines were identified and ranked. An evaluation method based on airline payback period was developed for the purpose of identifying the most promising concepts. The method used available test data and analytical models along with conceptual/preliminary designs to predict the performance improvements, weight, installation characteristics, cost for new production and retrofit, maintenance cost, and qualitative characteristics of candidate concepts. These results were used to arrive at the concept payback period, which is the time required for an airline to recover the investment cost of concept implementation

\u3cem\u3eIn situ\u3c/em\u3e infrared videography of sand scorpion nighttime surface activity

Sand scorpions make burrows from which they emerge at night to seek mates and prey. Previous ecological studies have documented scorpion activities on the sand surface. Few studies, however, have videotaped scorpion movements in the context of understanding their sensory neurobiology. Our objective is to understand which signals guide scorpions as they emerge from and return to their burrows. Candidate stimuli include chemical trails, footsteps, celestial patterns, geomagnetic cues, humidity and/or temperature gradients, distinctive scents from the burrow, seismic echolocation, memory, or landmark orientation. We videotaped scorpions to learn whether they return to their burrows by the same path they use as they exit, or whether they use a different route. The answer to this question could help eliminate some of the candidate stimuli from consideration. We used pole-mounted infrared surveillance cameras that relayed images to a digital recorder to monitor and record the movements of sand scorpions (Paruroctonus utahensis) near Monahans, Texas. Two-hour recording blocks of two animals on two consecutive nights revealed that the animals spent most of their time at the thresholds of their burrows, usually emerging briefly after an arthropod walked by. In each case, the scorpions took a looping path that did not retrace the route by which they exited their burrows. In additional experiments we used small lures to seismically entice scorpions from their burrows and monitored their movements as they returned to their burrows. These studies and other observations suggest that many of these sand scorpions do not spend much time on the sand surface; instead, they wait at the threshold of their burrows and ambush prey that wanders nearby

Inventory control methods for an integrated warehouse and retail television operation.

Thesis (M.B.A.)--Boston Universit

Neural Responses to Looming Objects in the Dragonfly

Dragonflies have high visual acuity, which, when combined with a remarkably fast visual response, allows them to hunt small insects with a high success rate. Rather than aiming at the prey’s current location, the dragonfly predicts the prey’s future location and intercepts the insect mid-flight. Eight bilateral pairs of large Target-Selective Descending Neurons (TSDNs) of the dragonfly ventral nerve cord respond to small, contrasting objects, which presumably represent potential prey. These interneurons are part of the neuronal circuitry that triggers small changes in wing angle and position to control flight during prey interception. In flight, dragonflies extend their legs out to catch the prey about 20 ms before contact. The current research investigates the role of the TSDNs in prey contact. Spiking traces from the nerve cord were recorded during the presentation of expanding black circles projected on a screen, which simulate approaching prey. Several loom sizes and speeds were used to cover a range of realistic and unrealistic rates of expansion. I hypothesized that the interneurons predict the time to contact (Tc) of the simulated looming stimuli. Looming-sensitive TSDNs fired at a consistent time before Tc, supporting the hypothesis

Engine component improvement: Performance improvement, JT9D-7 3.8 AR fan

A redesigned, fuel efficient fan for the JT9D-7 engine was tested. Tests were conducted to determine the effect of the 3.8 AR fan on performance, stability, operational characteristics, and noise of the JT9D-7 engine relative to the current 4.6 AR Bill-of-Material fan. The 3.8 AR fan provides increased fan efficiency due to a more advanced blade airfoil with increased chord, eliminating one part span shroud and reducing the number of fan blades and fan exit guide vanes. Engine testing at simulated cruise conditions demonstrated the predicted 1.3 percent improvement in specific fuel consumption with the redesigned 3.8 AR fan. Flight testing and sea level stand engine testing demonstrated exhaust gas temperature margins, fan and low pressure compressor stability, operational suitability, and noise levels comparable to the Bill-of-Material fan

JT9D ceramic outer air seal system refinement program

The abradability and durability characteristics of the plasma sprayed system were improved by refinement and optimization of the plasma spray process and the metal substrate design. The acceptability of the final seal system for engine testing was demonstrated by an extensive rig test program which included thermal shock tolerance, thermal gradient, thermal cycle, erosion, and abradability tests. An interim seal system design was also subjected to 2500 endurance test cycles in a JT9D-7 engine

JT8D revised high-pressure turbine cooling and other outer air seal program

The JT8D high pressure turbine was revised to reduce leakage between the blade tip shrouds and the outer air seal, and engine testing was performed to determine the effect on performance. The addition of a second knife-edge on the blade tip shroud, the extension of the honeycomb seal land to cover the added knife-edge and an existing spoiler on the shroud, and a material substitution in the seal support ring to improve thermal growth characteristics are included. A relocation of the blade cooling air discharge to insure adequate cooling flow is required. Significant specific fuel consumption and exhaust gas temperature improvements were demonstrated with the revised turbine in sea level and simulated altitude engine tests. Inspection of the revised seal hardware after these tests showed no unusual wear or degradation