NNEPEQ: Chemical equilibrium version of the Navy/NASA Engine Program

The Navy NASA Engine Program, NNEP, currently is in use at a large number of government agencies, commercial companies and universities. This computer code has bee used extensively to calculate the design and off-design (matched) performance of a broad range of turbine engines, ranging from subsonic turboprops to variable cycle engines for supersonic transports. Recently, there has been increased interest in applications for which NNEP was not capable of simulating, namely, high Mach applications, alternate fuels including cryogenics, and cycles such as the gas generator air-turbo-rocker (ATR). In addition, there is interest in cycles employing ejectors such as for military fighters. New engine component models had to be created for incorporation into NNEP, and it was found necessary to include chemical dissociation effects of high temperature gases. The incorporation of these extended capabilities into NNEP is discussed and some of the effects of these changes are illustrated

Investigation of oscillating cascade aerodynamics by an experimental influence coefficient technique

Fundamental experiments are performed in the NASA Lewis Transonic Oscillating Cascade Facility to investigate the torsion mode unsteady aerodynamics of a biconvex airfoil cascade at realistic values of the reduced frequency for all interblade phase angles at a specified mean flow condition. In particular, an unsteady aerodynamic influence coefficient technique is developed and utilized in which only one airfoil in the cascade is oscillated at a time and the resulting airfoil surface unsteady pressure distribution measured on one dynamically instrumented airfoil. The unsteady aerodynamics of an equivalent cascade with all airfoils oscillating at a specified interblade phase angle are then determined through a vector summation of these data. These influence coefficient determined oscillation cascade data are correlated with data obtained in this cascade with all airfoils oscillating at several interblade phase angle values. The influence coefficients are then utilized to determine the unsteady aerodynamics of the cascade for all interblade phase angles, with these unique data subsequently correlated with predictions from a linearized unsteady cascade model

Wind tunnel wall effects in a linear oscillating cascade

Experiments in a linear oscillating cascade reveal that the wind tunnel walls enclosing the airfoils have, in some cases, a detrimental effect on the oscillating cascade aerodynamics. In a subsonic flow field, biconvex airfoils are driven simultaneously in harmonic, torsion-mode oscillations for a range of interblade phase angle values. It is found that the cascade dynamic periodicity - the airfoil to airfoil variation in unsteady surface pressure - is good for some values of interblade phase angle but poor for others. Correlation of the unsteady pressure data with oscillating flat plate cascade predictions is generally good for conditions where the periodicity is good and poor where the periodicity is poor. Calculations based upon linearized unsteady aerodynamic theory indicate that pressure waves reflected from the wind tunnel walls are responsible for the cases where there is poor periodicity and poor correlation with the predictions

Experimental investigation of transonic oscillating cascade aerodynamics

Fundamental experiments are performed in the NASA Lewis Transonic Oscillating Cascade Facility to investigate the subsonic and transonic aerodynamics of cascaded airfoils executing torsion mode oscillations at realistic values of reduced frequency. In particular, an unsteady aerodynamic influence coefficient technique is developed and utilized. In this technique, only one airfoil in the cascade is oscillated at a time, with the resulting airfoil surface unsteady pressure distribution measured on one dynamically instrumented reference airfoil. The unsteady aerodynamics of an equivalent cascade with all airfoils oscillating at any specified interblade phase angle are then determined through a vector summation of these data. These influence coefficient determined oscillating cascade data were correlated with: (1) data obtained in this cascade with all airfoils oscillating at several interblade phase angle values; and (2) predictions from a classical linearized unsteady cascade model

Liquidity and Market Structure

Market liquidity is modeled as being determined by the demand and supply of immediacy. Exogenous liquidity events coupled with the risk of delayed trade create a demand for immediacy. Market makers supply immediacy by their continuous presence. and willingness to bear risk during the time period between the arrival of final buyers and sellers. In the long run the number of market makers adjusts to equate the supply and demand for immediacy. This determine the equilibrium level of liquidity in the market. The lower is the autocorrelation in rates of return, the higher is the equilibrium level of liquidity.

Unsteady aerodynamics of an oscillating cascade in a compressible flow field

Fundamental experiments were performed in the NASA Lewis Transonic Oscillating Cascade Facility to investigate and quantify the unsteady aerodynamics of a cascade of biconvex airfoils executing torsion-mode oscillations at realistic reduced frequencies. Flush-mounted, high-response miniature pressure transducers were used to measure the unsteady airfoil surface pressures. The pressures were measured for three interblade phase angles at two inlet Mach numbers, 0.65 and 0.80, and two incidence angles, 0 and 7 deg. The time-variant pressures were analyzed by means of discrete Fourier transform techniques, and these unique data were then compared with predictions from a linearized unsteady cascade model. The experimental results indicate that the interblade phase angle had a major effect on the chordwise distributions of the airfoil surface unsteady pressure, and that reduced frequency, incidence angle, and Mach number had a somewhat less significant effect

Why Substantive Criminal Law - A Dialogue

In this dialogue, I have tried to address criticisms of the substantive criminal law, as a course and as a subject matter, made by a number of my students over several decades of teaching the subject. In away it is rather personal since it consists of the criticisms of my students and my apologia for what I have tried to do. That, however, would hardly be worth doing unless it is the case, as I believe it is, that these criticisms are widespread and that my responses speak to what is generally done in criminal law courses in this country

Carmack Amendment in the State Courts

Prior to the leading case of Adams Express Co. v. Croninger,\u27- decided January 6th, 1913, there was much diversity in the decisions of the state courts as to the validity of contracts between shippers and carriers limiting the amount of the carrier\u27s liability for injuries to goods shipped. Such limitations were held valid in some states, but invalid in others, and in some were declared invalid by statutes or constitutional provisions.2 State rules were applied to interstate as well as intrastate shipments, it being supposed that Congress had not legislated upon the subject. The CARMACK AmlNDVNT of i9o6s provided that every carier receiving property for interstate shipment should issue a receipt or bill of lading therefor, and be liable for any injury to such property caused by it or by any connecting carrier, and concluded with the words no contract, receipt, rule or regulation shall exempt such common carrier, railroad or transportation company from the liability hereby imposed; Provided, that nothing in this section shall deprive any holder of such receipt or bill of lading of any remedy or right of action which he had under existing law. It had been thought, both by state and by federal courts, that the proviso above quoted was intended to save to the shipper whatever rights he had under existing state law; and accordingly both state and federal courts continued to apply the rules, different in different jurisdictions, which had controlled before the passage of that amendment.\u27 In the Croninger case, however, -it was held by the United States Supreme Court that Congress had evinced, in the CARMACYC AMXNDMrNT, an intention to assume control over the whole field of the liability of common carriers on interstate shipments, and to supersede and abrogate all state laws in relation thereto; and that the proviso saving to the shipper his rights \u27under existing, law meant to save him only such rights as he had under existing federal law. There was no existing federal law forbidding contracts limiting the amount of the carrier\u27s liability (a limitation of amount not being an exemption within the meaning of the amendment), and such contracts were therefore held to be valid, regardless of state rules or laws. Immediately following that decision, and in accordance with the doctrine there laid down, several state decisions holding such contracts invalid were reversed.5 The same rule was held to apply to contracts for the transportation of the baggage of a passenger, in Boston & Maine R. R. v. Hooker, where it was further held that the filed and published tariffs were binding on both carrier and shipper, and that regulations therein (including limitation of liability) were conclusively presumed to be a part of the contract of transportation. A year after the Hooker case, it was decided in Geo. N. Pierce Co. v. Wells Fargo & Co.,7 that under the CARMACK AMI=- MXNT a contract limiting the amount of the carrier\u27s liability for goods shipped between states was valid even though the stipulated amount was purely arbitrary and out of all proportion to the true value of the shipment, and even though the carrier knew that such true value was greatly in excess of the limit of liability. The theory of all these decisions was that Congress intended by its legislation to put all shippers of goods from state to state on precisely the same basis, to do away with discrimination of any kind in interstate transportation, and to make the laws governing shipments between states uniform and equal in their operation throughout the land

Francis A. Allen --An Appreciation

A tribute to Francis A. Alle